diff options
Diffstat (limited to 'kernel/tools/lguest')
| -rw-r--r-- | kernel/tools/lguest/.gitignore | 1 | ||||
| -rw-r--r-- | kernel/tools/lguest/Makefile | 13 | ||||
| -rw-r--r-- | kernel/tools/lguest/extract | 58 | ||||
| -rw-r--r-- | kernel/tools/lguest/lguest.c | 3410 | ||||
| -rw-r--r-- | kernel/tools/lguest/lguest.txt | 125 |
5 files changed, 3607 insertions, 0 deletions
diff --git a/kernel/tools/lguest/.gitignore b/kernel/tools/lguest/.gitignore new file mode 100644 index 000000000..115587fd5 --- /dev/null +++ b/kernel/tools/lguest/.gitignore @@ -0,0 +1 @@ +lguest diff --git a/kernel/tools/lguest/Makefile b/kernel/tools/lguest/Makefile new file mode 100644 index 000000000..a107b5e4d --- /dev/null +++ b/kernel/tools/lguest/Makefile @@ -0,0 +1,13 @@ +# This creates the demonstration utility "lguest" which runs a Linux guest. +CFLAGS:=-m32 -Wall -Wmissing-declarations -Wmissing-prototypes -O3 -U_FORTIFY_SOURCE -Iinclude + +all: lguest + +include/linux/virtio_types.h: ../../include/uapi/linux/virtio_types.h + mkdir -p include/linux 2>&1 || true + ln -sf ../../../../include/uapi/linux/virtio_types.h $@ + +lguest: include/linux/virtio_types.h + +clean: + rm -f lguest diff --git a/kernel/tools/lguest/extract b/kernel/tools/lguest/extract new file mode 100644 index 000000000..7730bb6e4 --- /dev/null +++ b/kernel/tools/lguest/extract @@ -0,0 +1,58 @@ +#! /bin/sh + +set -e + +PREFIX=$1 +shift + +trap 'rm -r $TMPDIR' 0 +TMPDIR=`mktemp -d` + +exec 3>/dev/null +for f; do + while IFS=" +" read -r LINE; do + case "$LINE" in + *$PREFIX:[0-9]*:\**) + NUM=`echo "$LINE" | sed "s/.*$PREFIX:\([0-9]*\).*/\1/"` + if [ -f $TMPDIR/$NUM ]; then + echo "$TMPDIR/$NUM already exits prior to $f" + exit 1 + fi + exec 3>>$TMPDIR/$NUM + echo $f | sed 's,\.\./,,g' > $TMPDIR/.$NUM + /bin/echo "$LINE" | sed -e "s/$PREFIX:[0-9]*//" -e "s/:\*/*/" >&3 + ;; + *$PREFIX:[0-9]*) + NUM=`echo "$LINE" | sed "s/.*$PREFIX:\([0-9]*\).*/\1/"` + if [ -f $TMPDIR/$NUM ]; then + echo "$TMPDIR/$NUM already exits prior to $f" + exit 1 + fi + exec 3>>$TMPDIR/$NUM + echo $f | sed 's,\.\./,,g' > $TMPDIR/.$NUM + /bin/echo "$LINE" | sed "s/$PREFIX:[0-9]*//" >&3 + ;; + *:\**) + /bin/echo "$LINE" | sed -e "s/:\*/*/" -e "s,/\*\*/,," >&3 + echo >&3 + exec 3>/dev/null + ;; + *) + /bin/echo "$LINE" >&3 + ;; + esac + done < $f + echo >&3 + exec 3>/dev/null +done + +LASTFILE="" +for f in $TMPDIR/*; do + if [ "$LASTFILE" != $(cat $TMPDIR/.$(basename $f) ) ]; then + LASTFILE=$(cat $TMPDIR/.$(basename $f) ) + echo "[ $LASTFILE ]" + fi + cat $f +done + diff --git a/kernel/tools/lguest/lguest.c b/kernel/tools/lguest/lguest.c new file mode 100644 index 000000000..e44052483 --- /dev/null +++ b/kernel/tools/lguest/lguest.c @@ -0,0 +1,3410 @@ +/*P:100 + * This is the Launcher code, a simple program which lays out the "physical" + * memory for the new Guest by mapping the kernel image and the virtual + * devices, then opens /dev/lguest to tell the kernel about the Guest and + * control it. +:*/ +#define _LARGEFILE64_SOURCE +#define _GNU_SOURCE +#include <stdio.h> +#include <string.h> +#include <unistd.h> +#include <err.h> +#include <stdint.h> +#include <stdlib.h> +#include <elf.h> +#include <sys/mman.h> +#include <sys/param.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <sys/wait.h> +#include <sys/eventfd.h> +#include <fcntl.h> +#include <stdbool.h> +#include <errno.h> +#include <ctype.h> +#include <sys/socket.h> +#include <sys/ioctl.h> +#include <sys/time.h> +#include <time.h> +#include <netinet/in.h> +#include <net/if.h> +#include <linux/sockios.h> +#include <linux/if_tun.h> +#include <sys/uio.h> +#include <termios.h> +#include <getopt.h> +#include <assert.h> +#include <sched.h> +#include <limits.h> +#include <stddef.h> +#include <signal.h> +#include <pwd.h> +#include <grp.h> +#include <sys/user.h> +#include <linux/pci_regs.h> + +#ifndef VIRTIO_F_ANY_LAYOUT +#define VIRTIO_F_ANY_LAYOUT 27 +#endif + +/*L:110 + * We can ignore the 43 include files we need for this program, but I do want + * to draw attention to the use of kernel-style types. + * + * As Linus said, "C is a Spartan language, and so should your naming be." I + * like these abbreviations, so we define them here. Note that u64 is always + * unsigned long long, which works on all Linux systems: this means that we can + * use %llu in printf for any u64. + */ +typedef unsigned long long u64; +typedef uint32_t u32; +typedef uint16_t u16; +typedef uint8_t u8; +/*:*/ + +#define VIRTIO_CONFIG_NO_LEGACY +#define VIRTIO_PCI_NO_LEGACY +#define VIRTIO_BLK_NO_LEGACY +#define VIRTIO_NET_NO_LEGACY + +/* Use in-kernel ones, which defines VIRTIO_F_VERSION_1 */ +#include "../../include/uapi/linux/virtio_config.h" +#include "../../include/uapi/linux/virtio_net.h" +#include "../../include/uapi/linux/virtio_blk.h" +#include "../../include/uapi/linux/virtio_console.h" +#include "../../include/uapi/linux/virtio_rng.h" +#include <linux/virtio_ring.h> +#include "../../include/uapi/linux/virtio_pci.h" +#include <asm/bootparam.h> +#include "../../include/linux/lguest_launcher.h" + +#define BRIDGE_PFX "bridge:" +#ifndef SIOCBRADDIF +#define SIOCBRADDIF 0x89a2 /* add interface to bridge */ +#endif +/* We can have up to 256 pages for devices. */ +#define DEVICE_PAGES 256 +/* This will occupy 3 pages: it must be a power of 2. */ +#define VIRTQUEUE_NUM 256 + +/*L:120 + * verbose is both a global flag and a macro. The C preprocessor allows + * this, and although I wouldn't recommend it, it works quite nicely here. + */ +static bool verbose; +#define verbose(args...) \ + do { if (verbose) printf(args); } while(0) +/*:*/ + +/* The pointer to the start of guest memory. */ +static void *guest_base; +/* The maximum guest physical address allowed, and maximum possible. */ +static unsigned long guest_limit, guest_max, guest_mmio; +/* The /dev/lguest file descriptor. */ +static int lguest_fd; + +/* a per-cpu variable indicating whose vcpu is currently running */ +static unsigned int __thread cpu_id; + +/* 5 bit device number in the PCI_CONFIG_ADDR => 32 only */ +#define MAX_PCI_DEVICES 32 + +/* This is our list of devices. */ +struct device_list { + /* Counter to assign interrupt numbers. */ + unsigned int next_irq; + + /* Counter to print out convenient device numbers. */ + unsigned int device_num; + + /* PCI devices. */ + struct device *pci[MAX_PCI_DEVICES]; +}; + +/* The list of Guest devices, based on command line arguments. */ +static struct device_list devices; + +struct virtio_pci_cfg_cap { + struct virtio_pci_cap cap; + u32 pci_cfg_data; /* Data for BAR access. */ +}; + +struct virtio_pci_mmio { + struct virtio_pci_common_cfg cfg; + u16 notify; + u8 isr; + u8 padding; + /* Device-specific configuration follows this. */ +}; + +/* This is the layout (little-endian) of the PCI config space. */ +struct pci_config { + u16 vendor_id, device_id; + u16 command, status; + u8 revid, prog_if, subclass, class; + u8 cacheline_size, lat_timer, header_type, bist; + u32 bar[6]; + u32 cardbus_cis_ptr; + u16 subsystem_vendor_id, subsystem_device_id; + u32 expansion_rom_addr; + u8 capabilities, reserved1[3]; + u32 reserved2; + u8 irq_line, irq_pin, min_grant, max_latency; + + /* Now, this is the linked capability list. */ + struct virtio_pci_cap common; + struct virtio_pci_notify_cap notify; + struct virtio_pci_cap isr; + struct virtio_pci_cap device; + struct virtio_pci_cfg_cap cfg_access; +}; + +/* The device structure describes a single device. */ +struct device { + /* The name of this device, for --verbose. */ + const char *name; + + /* Any queues attached to this device */ + struct virtqueue *vq; + + /* Is it operational */ + bool running; + + /* Has it written FEATURES_OK but not re-checked it? */ + bool wrote_features_ok; + + /* PCI configuration */ + union { + struct pci_config config; + u32 config_words[sizeof(struct pci_config) / sizeof(u32)]; + }; + + /* Features we offer, and those accepted. */ + u64 features, features_accepted; + + /* Device-specific config hangs off the end of this. */ + struct virtio_pci_mmio *mmio; + + /* PCI MMIO resources (all in BAR0) */ + size_t mmio_size; + u32 mmio_addr; + + /* Device-specific data. */ + void *priv; +}; + +/* The virtqueue structure describes a queue attached to a device. */ +struct virtqueue { + struct virtqueue *next; + + /* Which device owns me. */ + struct device *dev; + + /* Name for printing errors. */ + const char *name; + + /* The actual ring of buffers. */ + struct vring vring; + + /* The information about this virtqueue (we only use queue_size on) */ + struct virtio_pci_common_cfg pci_config; + + /* Last available index we saw. */ + u16 last_avail_idx; + + /* How many are used since we sent last irq? */ + unsigned int pending_used; + + /* Eventfd where Guest notifications arrive. */ + int eventfd; + + /* Function for the thread which is servicing this virtqueue. */ + void (*service)(struct virtqueue *vq); + pid_t thread; +}; + +/* Remember the arguments to the program so we can "reboot" */ +static char **main_args; + +/* The original tty settings to restore on exit. */ +static struct termios orig_term; + +/* + * We have to be careful with barriers: our devices are all run in separate + * threads and so we need to make sure that changes visible to the Guest happen + * in precise order. + */ +#define wmb() __asm__ __volatile__("" : : : "memory") +#define rmb() __asm__ __volatile__("lock; addl $0,0(%%esp)" : : : "memory") +#define mb() __asm__ __volatile__("lock; addl $0,0(%%esp)" : : : "memory") + +/* Wrapper for the last available index. Makes it easier to change. */ +#define lg_last_avail(vq) ((vq)->last_avail_idx) + +/* + * The virtio configuration space is defined to be little-endian. x86 is + * little-endian too, but it's nice to be explicit so we have these helpers. + */ +#define cpu_to_le16(v16) (v16) +#define cpu_to_le32(v32) (v32) +#define cpu_to_le64(v64) (v64) +#define le16_to_cpu(v16) (v16) +#define le32_to_cpu(v32) (v32) +#define le64_to_cpu(v64) (v64) + +/* + * A real device would ignore weird/non-compliant driver behaviour. We + * stop and flag it, to help debugging Linux problems. + */ +#define bad_driver(d, fmt, ...) \ + errx(1, "%s: bad driver: " fmt, (d)->name, ## __VA_ARGS__) +#define bad_driver_vq(vq, fmt, ...) \ + errx(1, "%s vq %s: bad driver: " fmt, (vq)->dev->name, \ + vq->name, ## __VA_ARGS__) + +/* Is this iovec empty? */ +static bool iov_empty(const struct iovec iov[], unsigned int num_iov) +{ + unsigned int i; + + for (i = 0; i < num_iov; i++) + if (iov[i].iov_len) + return false; + return true; +} + +/* Take len bytes from the front of this iovec. */ +static void iov_consume(struct device *d, + struct iovec iov[], unsigned num_iov, + void *dest, unsigned len) +{ + unsigned int i; + + for (i = 0; i < num_iov; i++) { + unsigned int used; + + used = iov[i].iov_len < len ? iov[i].iov_len : len; + if (dest) { + memcpy(dest, iov[i].iov_base, used); + dest += used; + } + iov[i].iov_base += used; + iov[i].iov_len -= used; + len -= used; + } + if (len != 0) + bad_driver(d, "iovec too short!"); +} + +/*L:100 + * The Launcher code itself takes us out into userspace, that scary place where + * pointers run wild and free! Unfortunately, like most userspace programs, + * it's quite boring (which is why everyone likes to hack on the kernel!). + * Perhaps if you make up an Lguest Drinking Game at this point, it will get + * you through this section. Or, maybe not. + * + * The Launcher sets up a big chunk of memory to be the Guest's "physical" + * memory and stores it in "guest_base". In other words, Guest physical == + * Launcher virtual with an offset. + * + * This can be tough to get your head around, but usually it just means that we + * use these trivial conversion functions when the Guest gives us its + * "physical" addresses: + */ +static void *from_guest_phys(unsigned long addr) +{ + return guest_base + addr; +} + +static unsigned long to_guest_phys(const void *addr) +{ + return (addr - guest_base); +} + +/*L:130 + * Loading the Kernel. + * + * We start with couple of simple helper routines. open_or_die() avoids + * error-checking code cluttering the callers: + */ +static int open_or_die(const char *name, int flags) +{ + int fd = open(name, flags); + if (fd < 0) + err(1, "Failed to open %s", name); + return fd; +} + +/* map_zeroed_pages() takes a number of pages. */ +static void *map_zeroed_pages(unsigned int num) +{ + int fd = open_or_die("/dev/zero", O_RDONLY); + void *addr; + + /* + * We use a private mapping (ie. if we write to the page, it will be + * copied). We allocate an extra two pages PROT_NONE to act as guard + * pages against read/write attempts that exceed allocated space. + */ + addr = mmap(NULL, getpagesize() * (num+2), + PROT_NONE, MAP_PRIVATE, fd, 0); + + if (addr == MAP_FAILED) + err(1, "Mmapping %u pages of /dev/zero", num); + + if (mprotect(addr + getpagesize(), getpagesize() * num, + PROT_READ|PROT_WRITE) == -1) + err(1, "mprotect rw %u pages failed", num); + + /* + * One neat mmap feature is that you can close the fd, and it + * stays mapped. + */ + close(fd); + + /* Return address after PROT_NONE page */ + return addr + getpagesize(); +} + +/* Get some bytes which won't be mapped into the guest. */ +static unsigned long get_mmio_region(size_t size) +{ + unsigned long addr = guest_mmio; + size_t i; + + if (!size) + return addr; + + /* Size has to be a power of 2 (and multiple of 16) */ + for (i = 1; i < size; i <<= 1); + + guest_mmio += i; + + return addr; +} + +/* + * This routine is used to load the kernel or initrd. It tries mmap, but if + * that fails (Plan 9's kernel file isn't nicely aligned on page boundaries), + * it falls back to reading the memory in. + */ +static void map_at(int fd, void *addr, unsigned long offset, unsigned long len) +{ + ssize_t r; + + /* + * We map writable even though for some segments are marked read-only. + * The kernel really wants to be writable: it patches its own + * instructions. + * + * MAP_PRIVATE means that the page won't be copied until a write is + * done to it. This allows us to share untouched memory between + * Guests. + */ + if (mmap(addr, len, PROT_READ|PROT_WRITE, + MAP_FIXED|MAP_PRIVATE, fd, offset) != MAP_FAILED) + return; + + /* pread does a seek and a read in one shot: saves a few lines. */ + r = pread(fd, addr, len, offset); + if (r != len) + err(1, "Reading offset %lu len %lu gave %zi", offset, len, r); +} + +/* + * This routine takes an open vmlinux image, which is in ELF, and maps it into + * the Guest memory. ELF = Embedded Linking Format, which is the format used + * by all modern binaries on Linux including the kernel. + * + * The ELF headers give *two* addresses: a physical address, and a virtual + * address. We use the physical address; the Guest will map itself to the + * virtual address. + * + * We return the starting address. + */ +static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr) +{ + Elf32_Phdr phdr[ehdr->e_phnum]; + unsigned int i; + + /* + * Sanity checks on the main ELF header: an x86 executable with a + * reasonable number of correctly-sized program headers. + */ + if (ehdr->e_type != ET_EXEC + || ehdr->e_machine != EM_386 + || ehdr->e_phentsize != sizeof(Elf32_Phdr) + || ehdr->e_phnum < 1 || ehdr->e_phnum > 65536U/sizeof(Elf32_Phdr)) + errx(1, "Malformed elf header"); + + /* + * An ELF executable contains an ELF header and a number of "program" + * headers which indicate which parts ("segments") of the program to + * load where. + */ + + /* We read in all the program headers at once: */ + if (lseek(elf_fd, ehdr->e_phoff, SEEK_SET) < 0) + err(1, "Seeking to program headers"); + if (read(elf_fd, phdr, sizeof(phdr)) != sizeof(phdr)) + err(1, "Reading program headers"); + + /* + * Try all the headers: there are usually only three. A read-only one, + * a read-write one, and a "note" section which we don't load. + */ + for (i = 0; i < ehdr->e_phnum; i++) { + /* If this isn't a loadable segment, we ignore it */ + if (phdr[i].p_type != PT_LOAD) + continue; + + verbose("Section %i: size %i addr %p\n", + i, phdr[i].p_memsz, (void *)phdr[i].p_paddr); + + /* We map this section of the file at its physical address. */ + map_at(elf_fd, from_guest_phys(phdr[i].p_paddr), + phdr[i].p_offset, phdr[i].p_filesz); + } + + /* The entry point is given in the ELF header. */ + return ehdr->e_entry; +} + +/*L:150 + * A bzImage, unlike an ELF file, is not meant to be loaded. You're supposed + * to jump into it and it will unpack itself. We used to have to perform some + * hairy magic because the unpacking code scared me. + * + * Fortunately, Jeremy Fitzhardinge convinced me it wasn't that hard and wrote + * a small patch to jump over the tricky bits in the Guest, so now we just read + * the funky header so we know where in the file to load, and away we go! + */ +static unsigned long load_bzimage(int fd) +{ + struct boot_params boot; + int r; + /* Modern bzImages get loaded at 1M. */ + void *p = from_guest_phys(0x100000); + + /* + * Go back to the start of the file and read the header. It should be + * a Linux boot header (see Documentation/x86/boot.txt) + */ + lseek(fd, 0, SEEK_SET); + read(fd, &boot, sizeof(boot)); + + /* Inside the setup_hdr, we expect the magic "HdrS" */ + if (memcmp(&boot.hdr.header, "HdrS", 4) != 0) + errx(1, "This doesn't look like a bzImage to me"); + + /* Skip over the extra sectors of the header. */ + lseek(fd, (boot.hdr.setup_sects+1) * 512, SEEK_SET); + + /* Now read everything into memory. in nice big chunks. */ + while ((r = read(fd, p, 65536)) > 0) + p += r; + + /* Finally, code32_start tells us where to enter the kernel. */ + return boot.hdr.code32_start; +} + +/*L:140 + * Loading the kernel is easy when it's a "vmlinux", but most kernels + * come wrapped up in the self-decompressing "bzImage" format. With a little + * work, we can load those, too. + */ +static unsigned long load_kernel(int fd) +{ + Elf32_Ehdr hdr; + + /* Read in the first few bytes. */ + if (read(fd, &hdr, sizeof(hdr)) != sizeof(hdr)) + err(1, "Reading kernel"); + + /* If it's an ELF file, it starts with "\177ELF" */ + if (memcmp(hdr.e_ident, ELFMAG, SELFMAG) == 0) + return map_elf(fd, &hdr); + + /* Otherwise we assume it's a bzImage, and try to load it. */ + return load_bzimage(fd); +} + +/* + * This is a trivial little helper to align pages. Andi Kleen hated it because + * it calls getpagesize() twice: "it's dumb code." + * + * Kernel guys get really het up about optimization, even when it's not + * necessary. I leave this code as a reaction against that. + */ +static inline unsigned long page_align(unsigned long addr) +{ + /* Add upwards and truncate downwards. */ + return ((addr + getpagesize()-1) & ~(getpagesize()-1)); +} + +/*L:180 + * An "initial ram disk" is a disk image loaded into memory along with the + * kernel which the kernel can use to boot from without needing any drivers. + * Most distributions now use this as standard: the initrd contains the code to + * load the appropriate driver modules for the current machine. + * + * Importantly, James Morris works for RedHat, and Fedora uses initrds for its + * kernels. He sent me this (and tells me when I break it). + */ +static unsigned long load_initrd(const char *name, unsigned long mem) +{ + int ifd; + struct stat st; + unsigned long len; + + ifd = open_or_die(name, O_RDONLY); + /* fstat() is needed to get the file size. */ + if (fstat(ifd, &st) < 0) + err(1, "fstat() on initrd '%s'", name); + + /* + * We map the initrd at the top of memory, but mmap wants it to be + * page-aligned, so we round the size up for that. + */ + len = page_align(st.st_size); + map_at(ifd, from_guest_phys(mem - len), 0, st.st_size); + /* + * Once a file is mapped, you can close the file descriptor. It's a + * little odd, but quite useful. + */ + close(ifd); + verbose("mapped initrd %s size=%lu @ %p\n", name, len, (void*)mem-len); + + /* We return the initrd size. */ + return len; +} +/*:*/ + +/* + * Simple routine to roll all the commandline arguments together with spaces + * between them. + */ +static void concat(char *dst, char *args[]) +{ + unsigned int i, len = 0; + + for (i = 0; args[i]; i++) { + if (i) { + strcat(dst+len, " "); + len++; + } + strcpy(dst+len, args[i]); + len += strlen(args[i]); + } + /* In case it's empty. */ + dst[len] = '\0'; +} + +/*L:185 + * This is where we actually tell the kernel to initialize the Guest. We + * saw the arguments it expects when we looked at initialize() in lguest_user.c: + * the base of Guest "physical" memory, the top physical page to allow and the + * entry point for the Guest. + */ +static void tell_kernel(unsigned long start) +{ + unsigned long args[] = { LHREQ_INITIALIZE, + (unsigned long)guest_base, + guest_limit / getpagesize(), start, + (guest_mmio+getpagesize()-1) / getpagesize() }; + verbose("Guest: %p - %p (%#lx, MMIO %#lx)\n", + guest_base, guest_base + guest_limit, + guest_limit, guest_mmio); + lguest_fd = open_or_die("/dev/lguest", O_RDWR); + if (write(lguest_fd, args, sizeof(args)) < 0) + err(1, "Writing to /dev/lguest"); +} +/*:*/ + +/*L:200 + * Device Handling. + * + * When the Guest gives us a buffer, it sends an array of addresses and sizes. + * We need to make sure it's not trying to reach into the Launcher itself, so + * we have a convenient routine which checks it and exits with an error message + * if something funny is going on: + */ +static void *_check_pointer(struct device *d, + unsigned long addr, unsigned int size, + unsigned int line) +{ + /* + * Check if the requested address and size exceeds the allocated memory, + * or addr + size wraps around. + */ + if ((addr + size) > guest_limit || (addr + size) < addr) + bad_driver(d, "%s:%i: Invalid address %#lx", + __FILE__, line, addr); + /* + * We return a pointer for the caller's convenience, now we know it's + * safe to use. + */ + return from_guest_phys(addr); +} +/* A macro which transparently hands the line number to the real function. */ +#define check_pointer(d,addr,size) _check_pointer(d, addr, size, __LINE__) + +/* + * Each buffer in the virtqueues is actually a chain of descriptors. This + * function returns the next descriptor in the chain, or vq->vring.num if we're + * at the end. + */ +static unsigned next_desc(struct device *d, struct vring_desc *desc, + unsigned int i, unsigned int max) +{ + unsigned int next; + + /* If this descriptor says it doesn't chain, we're done. */ + if (!(desc[i].flags & VRING_DESC_F_NEXT)) + return max; + + /* Check they're not leading us off end of descriptors. */ + next = desc[i].next; + /* Make sure compiler knows to grab that: we don't want it changing! */ + wmb(); + + if (next >= max) + bad_driver(d, "Desc next is %u", next); + + return next; +} + +/* + * This actually sends the interrupt for this virtqueue, if we've used a + * buffer. + */ +static void trigger_irq(struct virtqueue *vq) +{ + unsigned long buf[] = { LHREQ_IRQ, vq->dev->config.irq_line }; + + /* Don't inform them if nothing used. */ + if (!vq->pending_used) + return; + vq->pending_used = 0; + + /* + * 2.4.7.1: + * + * If the VIRTIO_F_EVENT_IDX feature bit is not negotiated: + * The driver MUST set flags to 0 or 1. + */ + if (vq->vring.avail->flags > 1) + bad_driver_vq(vq, "avail->flags = %u\n", vq->vring.avail->flags); + + /* + * 2.4.7.2: + * + * If the VIRTIO_F_EVENT_IDX feature bit is not negotiated: + * + * - The device MUST ignore the used_event value. + * - After the device writes a descriptor index into the used ring: + * - If flags is 1, the device SHOULD NOT send an interrupt. + * - If flags is 0, the device MUST send an interrupt. + */ + if (vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT) { + return; + } + + /* + * 4.1.4.5.1: + * + * If MSI-X capability is disabled, the device MUST set the Queue + * Interrupt bit in ISR status before sending a virtqueue notification + * to the driver. + */ + vq->dev->mmio->isr = 0x1; + + /* Send the Guest an interrupt tell them we used something up. */ + if (write(lguest_fd, buf, sizeof(buf)) != 0) + err(1, "Triggering irq %i", vq->dev->config.irq_line); +} + +/* + * This looks in the virtqueue for the first available buffer, and converts + * it to an iovec for convenient access. Since descriptors consist of some + * number of output then some number of input descriptors, it's actually two + * iovecs, but we pack them into one and note how many of each there were. + * + * This function waits if necessary, and returns the descriptor number found. + */ +static unsigned wait_for_vq_desc(struct virtqueue *vq, + struct iovec iov[], + unsigned int *out_num, unsigned int *in_num) +{ + unsigned int i, head, max; + struct vring_desc *desc; + u16 last_avail = lg_last_avail(vq); + + /* + * 2.4.7.1: + * + * The driver MUST handle spurious interrupts from the device. + * + * That's why this is a while loop. + */ + + /* There's nothing available? */ + while (last_avail == vq->vring.avail->idx) { + u64 event; + + /* + * Since we're about to sleep, now is a good time to tell the + * Guest about what we've used up to now. + */ + trigger_irq(vq); + + /* OK, now we need to know about added descriptors. */ + vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY; + + /* + * They could have slipped one in as we were doing that: make + * sure it's written, then check again. + */ + mb(); + if (last_avail != vq->vring.avail->idx) { + vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY; + break; + } + + /* Nothing new? Wait for eventfd to tell us they refilled. */ + if (read(vq->eventfd, &event, sizeof(event)) != sizeof(event)) + errx(1, "Event read failed?"); + + /* We don't need to be notified again. */ + vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY; + } + + /* Check it isn't doing very strange things with descriptor numbers. */ + if ((u16)(vq->vring.avail->idx - last_avail) > vq->vring.num) + bad_driver_vq(vq, "Guest moved used index from %u to %u", + last_avail, vq->vring.avail->idx); + + /* + * Make sure we read the descriptor number *after* we read the ring + * update; don't let the cpu or compiler change the order. + */ + rmb(); + + /* + * Grab the next descriptor number they're advertising, and increment + * the index we've seen. + */ + head = vq->vring.avail->ring[last_avail % vq->vring.num]; + lg_last_avail(vq)++; + + /* If their number is silly, that's a fatal mistake. */ + if (head >= vq->vring.num) + bad_driver_vq(vq, "Guest says index %u is available", head); + + /* When we start there are none of either input nor output. */ + *out_num = *in_num = 0; + + max = vq->vring.num; + desc = vq->vring.desc; + i = head; + + /* + * We have to read the descriptor after we read the descriptor number, + * but there's a data dependency there so the CPU shouldn't reorder + * that: no rmb() required. + */ + + do { + /* + * If this is an indirect entry, then this buffer contains a + * descriptor table which we handle as if it's any normal + * descriptor chain. + */ + if (desc[i].flags & VRING_DESC_F_INDIRECT) { + /* 2.4.5.3.1: + * + * The driver MUST NOT set the VIRTQ_DESC_F_INDIRECT + * flag unless the VIRTIO_F_INDIRECT_DESC feature was + * negotiated. + */ + if (!(vq->dev->features_accepted & + (1<<VIRTIO_RING_F_INDIRECT_DESC))) + bad_driver_vq(vq, "vq indirect not negotiated"); + + /* + * 2.4.5.3.1: + * + * The driver MUST NOT set the VIRTQ_DESC_F_INDIRECT + * flag within an indirect descriptor (ie. only one + * table per descriptor). + */ + if (desc != vq->vring.desc) + bad_driver_vq(vq, "Indirect within indirect"); + + /* + * Proposed update VIRTIO-134 spells this out: + * + * A driver MUST NOT set both VIRTQ_DESC_F_INDIRECT + * and VIRTQ_DESC_F_NEXT in flags. + */ + if (desc[i].flags & VRING_DESC_F_NEXT) + bad_driver_vq(vq, "indirect and next together"); + + if (desc[i].len % sizeof(struct vring_desc)) + bad_driver_vq(vq, + "Invalid size for indirect table"); + /* + * 2.4.5.3.2: + * + * The device MUST ignore the write-only flag + * (flags&VIRTQ_DESC_F_WRITE) in the descriptor that + * refers to an indirect table. + * + * We ignore it here: :) + */ + + max = desc[i].len / sizeof(struct vring_desc); + desc = check_pointer(vq->dev, desc[i].addr, desc[i].len); + i = 0; + + /* 2.4.5.3.1: + * + * A driver MUST NOT create a descriptor chain longer + * than the Queue Size of the device. + */ + if (max > vq->pci_config.queue_size) + bad_driver_vq(vq, + "indirect has too many entries"); + } + + /* Grab the first descriptor, and check it's OK. */ + iov[*out_num + *in_num].iov_len = desc[i].len; + iov[*out_num + *in_num].iov_base + = check_pointer(vq->dev, desc[i].addr, desc[i].len); + /* If this is an input descriptor, increment that count. */ + if (desc[i].flags & VRING_DESC_F_WRITE) + (*in_num)++; + else { + /* + * If it's an output descriptor, they're all supposed + * to come before any input descriptors. + */ + if (*in_num) + bad_driver_vq(vq, + "Descriptor has out after in"); + (*out_num)++; + } + + /* If we've got too many, that implies a descriptor loop. */ + if (*out_num + *in_num > max) + bad_driver_vq(vq, "Looped descriptor"); + } while ((i = next_desc(vq->dev, desc, i, max)) != max); + + return head; +} + +/* + * After we've used one of their buffers, we tell the Guest about it. Sometime + * later we'll want to send them an interrupt using trigger_irq(); note that + * wait_for_vq_desc() does that for us if it has to wait. + */ +static void add_used(struct virtqueue *vq, unsigned int head, int len) +{ + struct vring_used_elem *used; + + /* + * The virtqueue contains a ring of used buffers. Get a pointer to the + * next entry in that used ring. + */ + used = &vq->vring.used->ring[vq->vring.used->idx % vq->vring.num]; + used->id = head; + used->len = len; + /* Make sure buffer is written before we update index. */ + wmb(); + vq->vring.used->idx++; + vq->pending_used++; +} + +/* And here's the combo meal deal. Supersize me! */ +static void add_used_and_trigger(struct virtqueue *vq, unsigned head, int len) +{ + add_used(vq, head, len); + trigger_irq(vq); +} + +/* + * The Console + * + * We associate some data with the console for our exit hack. + */ +struct console_abort { + /* How many times have they hit ^C? */ + int count; + /* When did they start? */ + struct timeval start; +}; + +/* This is the routine which handles console input (ie. stdin). */ +static void console_input(struct virtqueue *vq) +{ + int len; + unsigned int head, in_num, out_num; + struct console_abort *abort = vq->dev->priv; + struct iovec iov[vq->vring.num]; + + /* Make sure there's a descriptor available. */ + head = wait_for_vq_desc(vq, iov, &out_num, &in_num); + if (out_num) + bad_driver_vq(vq, "Output buffers in console in queue?"); + + /* Read into it. This is where we usually wait. */ + len = readv(STDIN_FILENO, iov, in_num); + if (len <= 0) { + /* Ran out of input? */ + warnx("Failed to get console input, ignoring console."); + /* + * For simplicity, dying threads kill the whole Launcher. So + * just nap here. + */ + for (;;) + pause(); + } + + /* Tell the Guest we used a buffer. */ + add_used_and_trigger(vq, head, len); + + /* + * Three ^C within one second? Exit. + * + * This is such a hack, but works surprisingly well. Each ^C has to + * be in a buffer by itself, so they can't be too fast. But we check + * that we get three within about a second, so they can't be too + * slow. + */ + if (len != 1 || ((char *)iov[0].iov_base)[0] != 3) { + abort->count = 0; + return; + } + + abort->count++; + if (abort->count == 1) + gettimeofday(&abort->start, NULL); + else if (abort->count == 3) { + struct timeval now; + gettimeofday(&now, NULL); + /* Kill all Launcher processes with SIGINT, like normal ^C */ + if (now.tv_sec <= abort->start.tv_sec+1) + kill(0, SIGINT); + abort->count = 0; + } +} + +/* This is the routine which handles console output (ie. stdout). */ +static void console_output(struct virtqueue *vq) +{ + unsigned int head, out, in; + struct iovec iov[vq->vring.num]; + + /* We usually wait in here, for the Guest to give us something. */ + head = wait_for_vq_desc(vq, iov, &out, &in); + if (in) + bad_driver_vq(vq, "Input buffers in console output queue?"); + + /* writev can return a partial write, so we loop here. */ + while (!iov_empty(iov, out)) { + int len = writev(STDOUT_FILENO, iov, out); + if (len <= 0) { + warn("Write to stdout gave %i (%d)", len, errno); + break; + } + iov_consume(vq->dev, iov, out, NULL, len); + } + + /* + * We're finished with that buffer: if we're going to sleep, + * wait_for_vq_desc() will prod the Guest with an interrupt. + */ + add_used(vq, head, 0); +} + +/* + * The Network + * + * Handling output for network is also simple: we get all the output buffers + * and write them to /dev/net/tun. + */ +struct net_info { + int tunfd; +}; + +static void net_output(struct virtqueue *vq) +{ + struct net_info *net_info = vq->dev->priv; + unsigned int head, out, in; + struct iovec iov[vq->vring.num]; + + /* We usually wait in here for the Guest to give us a packet. */ + head = wait_for_vq_desc(vq, iov, &out, &in); + if (in) + bad_driver_vq(vq, "Input buffers in net output queue?"); + /* + * Send the whole thing through to /dev/net/tun. It expects the exact + * same format: what a coincidence! + */ + if (writev(net_info->tunfd, iov, out) < 0) + warnx("Write to tun failed (%d)?", errno); + + /* + * Done with that one; wait_for_vq_desc() will send the interrupt if + * all packets are processed. + */ + add_used(vq, head, 0); +} + +/* + * Handling network input is a bit trickier, because I've tried to optimize it. + * + * First we have a helper routine which tells is if from this file descriptor + * (ie. the /dev/net/tun device) will block: + */ +static bool will_block(int fd) +{ + fd_set fdset; + struct timeval zero = { 0, 0 }; + FD_ZERO(&fdset); + FD_SET(fd, &fdset); + return select(fd+1, &fdset, NULL, NULL, &zero) != 1; +} + +/* + * This handles packets coming in from the tun device to our Guest. Like all + * service routines, it gets called again as soon as it returns, so you don't + * see a while(1) loop here. + */ +static void net_input(struct virtqueue *vq) +{ + int len; + unsigned int head, out, in; + struct iovec iov[vq->vring.num]; + struct net_info *net_info = vq->dev->priv; + + /* + * Get a descriptor to write an incoming packet into. This will also + * send an interrupt if they're out of descriptors. + */ + head = wait_for_vq_desc(vq, iov, &out, &in); + if (out) + bad_driver_vq(vq, "Output buffers in net input queue?"); + + /* + * If it looks like we'll block reading from the tun device, send them + * an interrupt. + */ + if (vq->pending_used && will_block(net_info->tunfd)) + trigger_irq(vq); + + /* + * Read in the packet. This is where we normally wait (when there's no + * incoming network traffic). + */ + len = readv(net_info->tunfd, iov, in); + if (len <= 0) + warn("Failed to read from tun (%d).", errno); + + /* + * Mark that packet buffer as used, but don't interrupt here. We want + * to wait until we've done as much work as we can. + */ + add_used(vq, head, len); +} +/*:*/ + +/* This is the helper to create threads: run the service routine in a loop. */ +static int do_thread(void *_vq) +{ + struct virtqueue *vq = _vq; + + for (;;) + vq->service(vq); + return 0; +} + +/* + * When a child dies, we kill our entire process group with SIGTERM. This + * also has the side effect that the shell restores the console for us! + */ +static void kill_launcher(int signal) +{ + kill(0, SIGTERM); +} + +static void reset_vq_pci_config(struct virtqueue *vq) +{ + vq->pci_config.queue_size = VIRTQUEUE_NUM; + vq->pci_config.queue_enable = 0; +} + +static void reset_device(struct device *dev) +{ + struct virtqueue *vq; + + verbose("Resetting device %s\n", dev->name); + + /* Clear any features they've acked. */ + dev->features_accepted = 0; + + /* We're going to be explicitly killing threads, so ignore them. */ + signal(SIGCHLD, SIG_IGN); + + /* + * 4.1.4.3.1: + * + * The device MUST present a 0 in queue_enable on reset. + * + * This means we set it here, and reset the saved ones in every vq. + */ + dev->mmio->cfg.queue_enable = 0; + + /* Get rid of the virtqueue threads */ + for (vq = dev->vq; vq; vq = vq->next) { + vq->last_avail_idx = 0; + reset_vq_pci_config(vq); + if (vq->thread != (pid_t)-1) { + kill(vq->thread, SIGTERM); + waitpid(vq->thread, NULL, 0); + vq->thread = (pid_t)-1; + } + } + dev->running = false; + dev->wrote_features_ok = false; + + /* Now we care if threads die. */ + signal(SIGCHLD, (void *)kill_launcher); +} + +static void cleanup_devices(void) +{ + unsigned int i; + + for (i = 1; i < MAX_PCI_DEVICES; i++) { + struct device *d = devices.pci[i]; + if (!d) + continue; + reset_device(d); + } + + /* If we saved off the original terminal settings, restore them now. */ + if (orig_term.c_lflag & (ISIG|ICANON|ECHO)) + tcsetattr(STDIN_FILENO, TCSANOW, &orig_term); +} + +/*L:217 + * We do PCI. This is mainly done to let us test the kernel virtio PCI + * code. + */ + +/* Linux expects a PCI host bridge: ours is a dummy, and first on the bus. */ +static struct device pci_host_bridge; + +static void init_pci_host_bridge(void) +{ + pci_host_bridge.name = "PCI Host Bridge"; + pci_host_bridge.config.class = 0x06; /* bridge */ + pci_host_bridge.config.subclass = 0; /* host bridge */ + devices.pci[0] = &pci_host_bridge; +} + +/* The IO ports used to read the PCI config space. */ +#define PCI_CONFIG_ADDR 0xCF8 +#define PCI_CONFIG_DATA 0xCFC + +/* + * Not really portable, but does help readability: this is what the Guest + * writes to the PCI_CONFIG_ADDR IO port. + */ +union pci_config_addr { + struct { + unsigned mbz: 2; + unsigned offset: 6; + unsigned funcnum: 3; + unsigned devnum: 5; + unsigned busnum: 8; + unsigned reserved: 7; + unsigned enabled : 1; + } bits; + u32 val; +}; + +/* + * We cache what they wrote to the address port, so we know what they're + * talking about when they access the data port. + */ +static union pci_config_addr pci_config_addr; + +static struct device *find_pci_device(unsigned int index) +{ + return devices.pci[index]; +} + +/* PCI can do 1, 2 and 4 byte reads; we handle that here. */ +static void ioread(u16 off, u32 v, u32 mask, u32 *val) +{ + assert(off < 4); + assert(mask == 0xFF || mask == 0xFFFF || mask == 0xFFFFFFFF); + *val = (v >> (off * 8)) & mask; +} + +/* PCI can do 1, 2 and 4 byte writes; we handle that here. */ +static void iowrite(u16 off, u32 v, u32 mask, u32 *dst) +{ + assert(off < 4); + assert(mask == 0xFF || mask == 0xFFFF || mask == 0xFFFFFFFF); + *dst &= ~(mask << (off * 8)); + *dst |= (v & mask) << (off * 8); +} + +/* + * Where PCI_CONFIG_DATA accesses depends on the previous write to + * PCI_CONFIG_ADDR. + */ +static struct device *dev_and_reg(u32 *reg) +{ + if (!pci_config_addr.bits.enabled) + return NULL; + + if (pci_config_addr.bits.funcnum != 0) + return NULL; + + if (pci_config_addr.bits.busnum != 0) + return NULL; + + if (pci_config_addr.bits.offset * 4 >= sizeof(struct pci_config)) + return NULL; + + *reg = pci_config_addr.bits.offset; + return find_pci_device(pci_config_addr.bits.devnum); +} + +/* + * We can get invalid combinations of values while they're writing, so we + * only fault if they try to write with some invalid bar/offset/length. + */ +static bool valid_bar_access(struct device *d, + struct virtio_pci_cfg_cap *cfg_access) +{ + /* We only have 1 bar (BAR0) */ + if (cfg_access->cap.bar != 0) + return false; + + /* Check it's within BAR0. */ + if (cfg_access->cap.offset >= d->mmio_size + || cfg_access->cap.offset + cfg_access->cap.length > d->mmio_size) + return false; + + /* Check length is 1, 2 or 4. */ + if (cfg_access->cap.length != 1 + && cfg_access->cap.length != 2 + && cfg_access->cap.length != 4) + return false; + + /* + * 4.1.4.7.2: + * + * The driver MUST NOT write a cap.offset which is not a multiple of + * cap.length (ie. all accesses MUST be aligned). + */ + if (cfg_access->cap.offset % cfg_access->cap.length != 0) + return false; + + /* Return pointer into word in BAR0. */ + return true; +} + +/* Is this accessing the PCI config address port?. */ +static bool is_pci_addr_port(u16 port) +{ + return port >= PCI_CONFIG_ADDR && port < PCI_CONFIG_ADDR + 4; +} + +static bool pci_addr_iowrite(u16 port, u32 mask, u32 val) +{ + iowrite(port - PCI_CONFIG_ADDR, val, mask, + &pci_config_addr.val); + verbose("PCI%s: %#x/%x: bus %u dev %u func %u reg %u\n", + pci_config_addr.bits.enabled ? "" : " DISABLED", + val, mask, + pci_config_addr.bits.busnum, + pci_config_addr.bits.devnum, + pci_config_addr.bits.funcnum, + pci_config_addr.bits.offset); + return true; +} + +static void pci_addr_ioread(u16 port, u32 mask, u32 *val) +{ + ioread(port - PCI_CONFIG_ADDR, pci_config_addr.val, mask, val); +} + +/* Is this accessing the PCI config data port?. */ +static bool is_pci_data_port(u16 port) +{ + return port >= PCI_CONFIG_DATA && port < PCI_CONFIG_DATA + 4; +} + +static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask); + +static bool pci_data_iowrite(u16 port, u32 mask, u32 val) +{ + u32 reg, portoff; + struct device *d = dev_and_reg(®); + + /* Complain if they don't belong to a device. */ + if (!d) + return false; + + /* They can do 1 byte writes, etc. */ + portoff = port - PCI_CONFIG_DATA; + + /* + * PCI uses a weird way to determine the BAR size: the OS + * writes all 1's, and sees which ones stick. + */ + if (&d->config_words[reg] == &d->config.bar[0]) { + int i; + + iowrite(portoff, val, mask, &d->config.bar[0]); + for (i = 0; (1 << i) < d->mmio_size; i++) + d->config.bar[0] &= ~(1 << i); + return true; + } else if ((&d->config_words[reg] > &d->config.bar[0] + && &d->config_words[reg] <= &d->config.bar[6]) + || &d->config_words[reg] == &d->config.expansion_rom_addr) { + /* Allow writing to any other BAR, or expansion ROM */ + iowrite(portoff, val, mask, &d->config_words[reg]); + return true; + /* We let them overide latency timer and cacheline size */ + } else if (&d->config_words[reg] == (void *)&d->config.cacheline_size) { + /* Only let them change the first two fields. */ + if (mask == 0xFFFFFFFF) + mask = 0xFFFF; + iowrite(portoff, val, mask, &d->config_words[reg]); + return true; + } else if (&d->config_words[reg] == (void *)&d->config.command + && mask == 0xFFFF) { + /* Ignore command writes. */ + return true; + } else if (&d->config_words[reg] + == (void *)&d->config.cfg_access.cap.bar + || &d->config_words[reg] + == &d->config.cfg_access.cap.length + || &d->config_words[reg] + == &d->config.cfg_access.cap.offset) { + + /* + * The VIRTIO_PCI_CAP_PCI_CFG capability + * provides a backdoor to access the MMIO + * regions without mapping them. Weird, but + * useful. + */ + iowrite(portoff, val, mask, &d->config_words[reg]); + return true; + } else if (&d->config_words[reg] == &d->config.cfg_access.pci_cfg_data) { + u32 write_mask; + + /* + * 4.1.4.7.1: + * + * Upon detecting driver write access to pci_cfg_data, the + * device MUST execute a write access at offset cap.offset at + * BAR selected by cap.bar using the first cap.length bytes + * from pci_cfg_data. + */ + + /* Must be bar 0 */ + if (!valid_bar_access(d, &d->config.cfg_access)) + return false; + + iowrite(portoff, val, mask, &d->config.cfg_access.pci_cfg_data); + + /* + * Now emulate a write. The mask we use is set by + * len, *not* this write! + */ + write_mask = (1ULL<<(8*d->config.cfg_access.cap.length)) - 1; + verbose("Window writing %#x/%#x to bar %u, offset %u len %u\n", + d->config.cfg_access.pci_cfg_data, write_mask, + d->config.cfg_access.cap.bar, + d->config.cfg_access.cap.offset, + d->config.cfg_access.cap.length); + + emulate_mmio_write(d, d->config.cfg_access.cap.offset, + d->config.cfg_access.pci_cfg_data, + write_mask); + return true; + } + + /* + * 4.1.4.1: + * + * The driver MUST NOT write into any field of the capability + * structure, with the exception of those with cap_type + * VIRTIO_PCI_CAP_PCI_CFG... + */ + return false; +} + +static u32 emulate_mmio_read(struct device *d, u32 off, u32 mask); + +static void pci_data_ioread(u16 port, u32 mask, u32 *val) +{ + u32 reg; + struct device *d = dev_and_reg(®); + + if (!d) + return; + + /* Read through the PCI MMIO access window is special */ + if (&d->config_words[reg] == &d->config.cfg_access.pci_cfg_data) { + u32 read_mask; + + /* + * 4.1.4.7.1: + * + * Upon detecting driver read access to pci_cfg_data, the + * device MUST execute a read access of length cap.length at + * offset cap.offset at BAR selected by cap.bar and store the + * first cap.length bytes in pci_cfg_data. + */ + /* Must be bar 0 */ + if (!valid_bar_access(d, &d->config.cfg_access)) + bad_driver(d, + "Invalid cfg_access to bar%u, offset %u len %u", + d->config.cfg_access.cap.bar, + d->config.cfg_access.cap.offset, + d->config.cfg_access.cap.length); + + /* + * Read into the window. The mask we use is set by + * len, *not* this read! + */ + read_mask = (1ULL<<(8*d->config.cfg_access.cap.length))-1; + d->config.cfg_access.pci_cfg_data + = emulate_mmio_read(d, + d->config.cfg_access.cap.offset, + read_mask); + verbose("Window read %#x/%#x from bar %u, offset %u len %u\n", + d->config.cfg_access.pci_cfg_data, read_mask, + d->config.cfg_access.cap.bar, + d->config.cfg_access.cap.offset, + d->config.cfg_access.cap.length); + } + ioread(port - PCI_CONFIG_DATA, d->config_words[reg], mask, val); +} + +/*L:216 + * This is where we emulate a handful of Guest instructions. It's ugly + * and we used to do it in the kernel but it grew over time. + */ + +/* + * We use the ptrace syscall's pt_regs struct to talk about registers + * to lguest: these macros convert the names to the offsets. + */ +#define getreg(name) getreg_off(offsetof(struct user_regs_struct, name)) +#define setreg(name, val) \ + setreg_off(offsetof(struct user_regs_struct, name), (val)) + +static u32 getreg_off(size_t offset) +{ + u32 r; + unsigned long args[] = { LHREQ_GETREG, offset }; + + if (pwrite(lguest_fd, args, sizeof(args), cpu_id) < 0) + err(1, "Getting register %u", offset); + if (pread(lguest_fd, &r, sizeof(r), cpu_id) != sizeof(r)) + err(1, "Reading register %u", offset); + + return r; +} + +static void setreg_off(size_t offset, u32 val) +{ + unsigned long args[] = { LHREQ_SETREG, offset, val }; + + if (pwrite(lguest_fd, args, sizeof(args), cpu_id) < 0) + err(1, "Setting register %u", offset); +} + +/* Get register by instruction encoding */ +static u32 getreg_num(unsigned regnum, u32 mask) +{ + /* 8 bit ops use regnums 4-7 for high parts of word */ + if (mask == 0xFF && (regnum & 0x4)) + return getreg_num(regnum & 0x3, 0xFFFF) >> 8; + + switch (regnum) { + case 0: return getreg(eax) & mask; + case 1: return getreg(ecx) & mask; + case 2: return getreg(edx) & mask; + case 3: return getreg(ebx) & mask; + case 4: return getreg(esp) & mask; + case 5: return getreg(ebp) & mask; + case 6: return getreg(esi) & mask; + case 7: return getreg(edi) & mask; + } + abort(); +} + +/* Set register by instruction encoding */ +static void setreg_num(unsigned regnum, u32 val, u32 mask) +{ + /* Don't try to set bits out of range */ + assert(~(val & ~mask)); + + /* 8 bit ops use regnums 4-7 for high parts of word */ + if (mask == 0xFF && (regnum & 0x4)) { + /* Construct the 16 bits we want. */ + val = (val << 8) | getreg_num(regnum & 0x3, 0xFF); + setreg_num(regnum & 0x3, val, 0xFFFF); + return; + } + + switch (regnum) { + case 0: setreg(eax, val | (getreg(eax) & ~mask)); return; + case 1: setreg(ecx, val | (getreg(ecx) & ~mask)); return; + case 2: setreg(edx, val | (getreg(edx) & ~mask)); return; + case 3: setreg(ebx, val | (getreg(ebx) & ~mask)); return; + case 4: setreg(esp, val | (getreg(esp) & ~mask)); return; + case 5: setreg(ebp, val | (getreg(ebp) & ~mask)); return; + case 6: setreg(esi, val | (getreg(esi) & ~mask)); return; + case 7: setreg(edi, val | (getreg(edi) & ~mask)); return; + } + abort(); +} + +/* Get bytes of displacement appended to instruction, from r/m encoding */ +static u32 insn_displacement_len(u8 mod_reg_rm) +{ + /* Switch on the mod bits */ + switch (mod_reg_rm >> 6) { + case 0: + /* If mod == 0, and r/m == 101, 16-bit displacement follows */ + if ((mod_reg_rm & 0x7) == 0x5) + return 2; + /* Normally, mod == 0 means no literal displacement */ + return 0; + case 1: + /* One byte displacement */ + return 1; + case 2: + /* Four byte displacement */ + return 4; + case 3: + /* Register mode */ + return 0; + } + abort(); +} + +static void emulate_insn(const u8 insn[]) +{ + unsigned long args[] = { LHREQ_TRAP, 13 }; + unsigned int insnlen = 0, in = 0, small_operand = 0, byte_access; + unsigned int eax, port, mask; + /* + * Default is to return all-ones on IO port reads, which traditionally + * means "there's nothing there". + */ + u32 val = 0xFFFFFFFF; + + /* + * This must be the Guest kernel trying to do something, not userspace! + * The bottom two bits of the CS segment register are the privilege + * level. + */ + if ((getreg(xcs) & 3) != 0x1) + goto no_emulate; + + /* Decoding x86 instructions is icky. */ + + /* + * Around 2.6.33, the kernel started using an emulation for the + * cmpxchg8b instruction in early boot on many configurations. This + * code isn't paravirtualized, and it tries to disable interrupts. + * Ignore it, which will Mostly Work. + */ + if (insn[insnlen] == 0xfa) { + /* "cli", or Clear Interrupt Enable instruction. Skip it. */ + insnlen = 1; + goto skip_insn; + } + + /* + * 0x66 is an "operand prefix". It means a 16, not 32 bit in/out. + */ + if (insn[insnlen] == 0x66) { + small_operand = 1; + /* The instruction is 1 byte so far, read the next byte. */ + insnlen = 1; + } + + /* If the lower bit isn't set, it's a single byte access */ + byte_access = !(insn[insnlen] & 1); + + /* + * Now we can ignore the lower bit and decode the 4 opcodes + * we need to emulate. + */ + switch (insn[insnlen] & 0xFE) { + case 0xE4: /* in <next byte>,%al */ + port = insn[insnlen+1]; + insnlen += 2; + in = 1; + break; + case 0xEC: /* in (%dx),%al */ + port = getreg(edx) & 0xFFFF; + insnlen += 1; + in = 1; + break; + case 0xE6: /* out %al,<next byte> */ + port = insn[insnlen+1]; + insnlen += 2; + break; + case 0xEE: /* out %al,(%dx) */ + port = getreg(edx) & 0xFFFF; + insnlen += 1; + break; + default: + /* OK, we don't know what this is, can't emulate. */ + goto no_emulate; + } + + /* Set a mask of the 1, 2 or 4 bytes, depending on size of IO */ + if (byte_access) + mask = 0xFF; + else if (small_operand) + mask = 0xFFFF; + else + mask = 0xFFFFFFFF; + + /* + * If it was an "IN" instruction, they expect the result to be read + * into %eax, so we change %eax. + */ + eax = getreg(eax); + + if (in) { + /* This is the PS/2 keyboard status; 1 means ready for output */ + if (port == 0x64) + val = 1; + else if (is_pci_addr_port(port)) + pci_addr_ioread(port, mask, &val); + else if (is_pci_data_port(port)) + pci_data_ioread(port, mask, &val); + + /* Clear the bits we're about to read */ + eax &= ~mask; + /* Copy bits in from val. */ + eax |= val & mask; + /* Now update the register. */ + setreg(eax, eax); + } else { + if (is_pci_addr_port(port)) { + if (!pci_addr_iowrite(port, mask, eax)) + goto bad_io; + } else if (is_pci_data_port(port)) { + if (!pci_data_iowrite(port, mask, eax)) + goto bad_io; + } + /* There are many other ports, eg. CMOS clock, serial + * and parallel ports, so we ignore them all. */ + } + + verbose("IO %s of %x to %u: %#08x\n", + in ? "IN" : "OUT", mask, port, eax); +skip_insn: + /* Finally, we've "done" the instruction, so move past it. */ + setreg(eip, getreg(eip) + insnlen); + return; + +bad_io: + warnx("Attempt to %s port %u (%#x mask)", + in ? "read from" : "write to", port, mask); + +no_emulate: + /* Inject trap into Guest. */ + if (write(lguest_fd, args, sizeof(args)) < 0) + err(1, "Reinjecting trap 13 for fault at %#x", getreg(eip)); +} + +static struct device *find_mmio_region(unsigned long paddr, u32 *off) +{ + unsigned int i; + + for (i = 1; i < MAX_PCI_DEVICES; i++) { + struct device *d = devices.pci[i]; + + if (!d) + continue; + if (paddr < d->mmio_addr) + continue; + if (paddr >= d->mmio_addr + d->mmio_size) + continue; + *off = paddr - d->mmio_addr; + return d; + } + return NULL; +} + +/* FIXME: Use vq array. */ +static struct virtqueue *vq_by_num(struct device *d, u32 num) +{ + struct virtqueue *vq = d->vq; + + while (num-- && vq) + vq = vq->next; + + return vq; +} + +static void save_vq_config(const struct virtio_pci_common_cfg *cfg, + struct virtqueue *vq) +{ + vq->pci_config = *cfg; +} + +static void restore_vq_config(struct virtio_pci_common_cfg *cfg, + struct virtqueue *vq) +{ + /* Only restore the per-vq part */ + size_t off = offsetof(struct virtio_pci_common_cfg, queue_size); + + memcpy((void *)cfg + off, (void *)&vq->pci_config + off, + sizeof(*cfg) - off); +} + +/* + * 4.1.4.3.2: + * + * The driver MUST configure the other virtqueue fields before + * enabling the virtqueue with queue_enable. + * + * When they enable the virtqueue, we check that their setup is valid. + */ +static void check_virtqueue(struct device *d, struct virtqueue *vq) +{ + /* Because lguest is 32 bit, all the descriptor high bits must be 0 */ + if (vq->pci_config.queue_desc_hi + || vq->pci_config.queue_avail_hi + || vq->pci_config.queue_used_hi) + bad_driver_vq(vq, "invalid 64-bit queue address"); + + /* + * 2.4.1: + * + * The driver MUST ensure that the physical address of the first byte + * of each virtqueue part is a multiple of the specified alignment + * value in the above table. + */ + if (vq->pci_config.queue_desc_lo % 16 + || vq->pci_config.queue_avail_lo % 2 + || vq->pci_config.queue_used_lo % 4) + bad_driver_vq(vq, "invalid alignment in queue addresses"); + + /* Initialize the virtqueue and check they're all in range. */ + vq->vring.num = vq->pci_config.queue_size; + vq->vring.desc = check_pointer(vq->dev, + vq->pci_config.queue_desc_lo, + sizeof(*vq->vring.desc) * vq->vring.num); + vq->vring.avail = check_pointer(vq->dev, + vq->pci_config.queue_avail_lo, + sizeof(*vq->vring.avail) + + (sizeof(vq->vring.avail->ring[0]) + * vq->vring.num)); + vq->vring.used = check_pointer(vq->dev, + vq->pci_config.queue_used_lo, + sizeof(*vq->vring.used) + + (sizeof(vq->vring.used->ring[0]) + * vq->vring.num)); + + /* + * 2.4.9.1: + * + * The driver MUST initialize flags in the used ring to 0 + * when allocating the used ring. + */ + if (vq->vring.used->flags != 0) + bad_driver_vq(vq, "invalid initial used.flags %#x", + vq->vring.used->flags); +} + +static void start_virtqueue(struct virtqueue *vq) +{ + /* + * Create stack for thread. Since the stack grows upwards, we point + * the stack pointer to the end of this region. + */ + char *stack = malloc(32768); + + /* Create a zero-initialized eventfd. */ + vq->eventfd = eventfd(0, 0); + if (vq->eventfd < 0) + err(1, "Creating eventfd"); + + /* + * CLONE_VM: because it has to access the Guest memory, and SIGCHLD so + * we get a signal if it dies. + */ + vq->thread = clone(do_thread, stack + 32768, CLONE_VM | SIGCHLD, vq); + if (vq->thread == (pid_t)-1) + err(1, "Creating clone"); +} + +static void start_virtqueues(struct device *d) +{ + struct virtqueue *vq; + + for (vq = d->vq; vq; vq = vq->next) { + if (vq->pci_config.queue_enable) + start_virtqueue(vq); + } +} + +static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask) +{ + struct virtqueue *vq; + + switch (off) { + case offsetof(struct virtio_pci_mmio, cfg.device_feature_select): + /* + * 4.1.4.3.1: + * + * The device MUST present the feature bits it is offering in + * device_feature, starting at bit device_feature_select ∗ 32 + * for any device_feature_select written by the driver + */ + if (val == 0) + d->mmio->cfg.device_feature = d->features; + else if (val == 1) + d->mmio->cfg.device_feature = (d->features >> 32); + else + d->mmio->cfg.device_feature = 0; + goto feature_write_through32; + case offsetof(struct virtio_pci_mmio, cfg.guest_feature_select): + if (val > 1) + bad_driver(d, "Unexpected driver select %u", val); + goto feature_write_through32; + case offsetof(struct virtio_pci_mmio, cfg.guest_feature): + if (d->mmio->cfg.guest_feature_select == 0) { + d->features_accepted &= ~((u64)0xFFFFFFFF); + d->features_accepted |= val; + } else { + assert(d->mmio->cfg.guest_feature_select == 1); + d->features_accepted &= 0xFFFFFFFF; + d->features_accepted |= ((u64)val) << 32; + } + /* + * 2.2.1: + * + * The driver MUST NOT accept a feature which the device did + * not offer + */ + if (d->features_accepted & ~d->features) + bad_driver(d, "over-accepted features %#llx of %#llx", + d->features_accepted, d->features); + goto feature_write_through32; + case offsetof(struct virtio_pci_mmio, cfg.device_status): { + u8 prev; + + verbose("%s: device status -> %#x\n", d->name, val); + /* + * 4.1.4.3.1: + * + * The device MUST reset when 0 is written to device_status, + * and present a 0 in device_status once that is done. + */ + if (val == 0) { + reset_device(d); + goto write_through8; + } + + /* 2.1.1: The driver MUST NOT clear a device status bit. */ + if (d->mmio->cfg.device_status & ~val) + bad_driver(d, "unset of device status bit %#x -> %#x", + d->mmio->cfg.device_status, val); + + /* + * 2.1.2: + * + * The device MUST NOT consume buffers or notify the driver + * before DRIVER_OK. + */ + if (val & VIRTIO_CONFIG_S_DRIVER_OK + && !(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER_OK)) + start_virtqueues(d); + + /* + * 3.1.1: + * + * The driver MUST follow this sequence to initialize a device: + * - Reset the device. + * - Set the ACKNOWLEDGE status bit: the guest OS has + * notice the device. + * - Set the DRIVER status bit: the guest OS knows how + * to drive the device. + * - Read device feature bits, and write the subset + * of feature bits understood by the OS and driver + * to the device. During this step the driver MAY + * read (but MUST NOT write) the device-specific + * configuration fields to check that it can + * support the device before accepting it. + * - Set the FEATURES_OK status bit. The driver + * MUST not accept new feature bits after this + * step. + * - Re-read device status to ensure the FEATURES_OK + * bit is still set: otherwise, the device does + * not support our subset of features and the + * device is unusable. + * - Perform device-specific setup, including + * discovery of virtqueues for the device, + * optional per-bus setup, reading and possibly + * writing the device’s virtio configuration + * space, and population of virtqueues. + * - Set the DRIVER_OK status bit. At this point the + * device is “live”. + */ + prev = 0; + switch (val & ~d->mmio->cfg.device_status) { + case VIRTIO_CONFIG_S_DRIVER_OK: + prev |= VIRTIO_CONFIG_S_FEATURES_OK; /* fall thru */ + case VIRTIO_CONFIG_S_FEATURES_OK: + prev |= VIRTIO_CONFIG_S_DRIVER; /* fall thru */ + case VIRTIO_CONFIG_S_DRIVER: + prev |= VIRTIO_CONFIG_S_ACKNOWLEDGE; /* fall thru */ + case VIRTIO_CONFIG_S_ACKNOWLEDGE: + break; + default: + bad_driver(d, "unknown device status bit %#x -> %#x", + d->mmio->cfg.device_status, val); + } + if (d->mmio->cfg.device_status != prev) + bad_driver(d, "unexpected status transition %#x -> %#x", + d->mmio->cfg.device_status, val); + + /* If they just wrote FEATURES_OK, we make sure they read */ + switch (val & ~d->mmio->cfg.device_status) { + case VIRTIO_CONFIG_S_FEATURES_OK: + d->wrote_features_ok = true; + break; + case VIRTIO_CONFIG_S_DRIVER_OK: + if (d->wrote_features_ok) + bad_driver(d, "did not re-read FEATURES_OK"); + break; + } + goto write_through8; + } + case offsetof(struct virtio_pci_mmio, cfg.queue_select): + vq = vq_by_num(d, val); + /* + * 4.1.4.3.1: + * + * The device MUST present a 0 in queue_size if the virtqueue + * corresponding to the current queue_select is unavailable. + */ + if (!vq) { + d->mmio->cfg.queue_size = 0; + goto write_through16; + } + /* Save registers for old vq, if it was a valid vq */ + if (d->mmio->cfg.queue_size) + save_vq_config(&d->mmio->cfg, + vq_by_num(d, d->mmio->cfg.queue_select)); + /* Restore the registers for the queue they asked for */ + restore_vq_config(&d->mmio->cfg, vq); + goto write_through16; + case offsetof(struct virtio_pci_mmio, cfg.queue_size): + /* + * 4.1.4.3.2: + * + * The driver MUST NOT write a value which is not a power of 2 + * to queue_size. + */ + if (val & (val-1)) + bad_driver(d, "invalid queue size %u", val); + if (d->mmio->cfg.queue_enable) + bad_driver(d, "changing queue size on live device"); + goto write_through16; + case offsetof(struct virtio_pci_mmio, cfg.queue_msix_vector): + bad_driver(d, "attempt to set MSIX vector to %u", val); + case offsetof(struct virtio_pci_mmio, cfg.queue_enable): { + struct virtqueue *vq = vq_by_num(d, d->mmio->cfg.queue_select); + + /* + * 4.1.4.3.2: + * + * The driver MUST NOT write a 0 to queue_enable. + */ + if (val != 1) + bad_driver(d, "setting queue_enable to %u", val); + + /* + * 3.1.1: + * + * 7. Perform device-specific setup, including discovery of + * virtqueues for the device, optional per-bus setup, + * reading and possibly writing the device’s virtio + * configuration space, and population of virtqueues. + * 8. Set the DRIVER_OK status bit. + * + * All our devices require all virtqueues to be enabled, so + * they should have done that before setting DRIVER_OK. + */ + if (d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER_OK) + bad_driver(d, "enabling vq after DRIVER_OK"); + + d->mmio->cfg.queue_enable = val; + save_vq_config(&d->mmio->cfg, vq); + check_virtqueue(d, vq); + goto write_through16; + } + case offsetof(struct virtio_pci_mmio, cfg.queue_notify_off): + bad_driver(d, "attempt to write to queue_notify_off"); + case offsetof(struct virtio_pci_mmio, cfg.queue_desc_lo): + case offsetof(struct virtio_pci_mmio, cfg.queue_desc_hi): + case offsetof(struct virtio_pci_mmio, cfg.queue_avail_lo): + case offsetof(struct virtio_pci_mmio, cfg.queue_avail_hi): + case offsetof(struct virtio_pci_mmio, cfg.queue_used_lo): + case offsetof(struct virtio_pci_mmio, cfg.queue_used_hi): + /* + * 4.1.4.3.2: + * + * The driver MUST configure the other virtqueue fields before + * enabling the virtqueue with queue_enable. + */ + if (d->mmio->cfg.queue_enable) + bad_driver(d, "changing queue on live device"); + + /* + * 3.1.1: + * + * The driver MUST follow this sequence to initialize a device: + *... + * 5. Set the FEATURES_OK status bit. The driver MUST not + * accept new feature bits after this step. + */ + if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_FEATURES_OK)) + bad_driver(d, "setting up vq before FEATURES_OK"); + + /* + * 6. Re-read device status to ensure the FEATURES_OK bit is + * still set... + */ + if (d->wrote_features_ok) + bad_driver(d, "didn't re-read FEATURES_OK before setup"); + + goto write_through32; + case offsetof(struct virtio_pci_mmio, notify): + vq = vq_by_num(d, val); + if (!vq) + bad_driver(d, "Invalid vq notification on %u", val); + /* Notify the process handling this vq by adding 1 to eventfd */ + write(vq->eventfd, "\1\0\0\0\0\0\0\0", 8); + goto write_through16; + case offsetof(struct virtio_pci_mmio, isr): + bad_driver(d, "Unexpected write to isr"); + /* Weird corner case: write to emerg_wr of console */ + case sizeof(struct virtio_pci_mmio) + + offsetof(struct virtio_console_config, emerg_wr): + if (strcmp(d->name, "console") == 0) { + char c = val; + write(STDOUT_FILENO, &c, 1); + goto write_through32; + } + /* Fall through... */ + default: + /* + * 4.1.4.3.2: + * + * The driver MUST NOT write to device_feature, num_queues, + * config_generation or queue_notify_off. + */ + bad_driver(d, "Unexpected write to offset %u", off); + } + +feature_write_through32: + /* + * 3.1.1: + * + * The driver MUST follow this sequence to initialize a device: + *... + * - Set the DRIVER status bit: the guest OS knows how + * to drive the device. + * - Read device feature bits, and write the subset + * of feature bits understood by the OS and driver + * to the device. + *... + * - Set the FEATURES_OK status bit. The driver MUST not + * accept new feature bits after this step. + */ + if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER)) + bad_driver(d, "feature write before VIRTIO_CONFIG_S_DRIVER"); + if (d->mmio->cfg.device_status & VIRTIO_CONFIG_S_FEATURES_OK) + bad_driver(d, "feature write after VIRTIO_CONFIG_S_FEATURES_OK"); + + /* + * 4.1.3.1: + * + * The driver MUST access each field using the “natural” access + * method, i.e. 32-bit accesses for 32-bit fields, 16-bit accesses for + * 16-bit fields and 8-bit accesses for 8-bit fields. + */ +write_through32: + if (mask != 0xFFFFFFFF) { + bad_driver(d, "non-32-bit write to offset %u (%#x)", + off, getreg(eip)); + return; + } + memcpy((char *)d->mmio + off, &val, 4); + return; + +write_through16: + if (mask != 0xFFFF) + bad_driver(d, "non-16-bit write to offset %u (%#x)", + off, getreg(eip)); + memcpy((char *)d->mmio + off, &val, 2); + return; + +write_through8: + if (mask != 0xFF) + bad_driver(d, "non-8-bit write to offset %u (%#x)", + off, getreg(eip)); + memcpy((char *)d->mmio + off, &val, 1); + return; +} + +static u32 emulate_mmio_read(struct device *d, u32 off, u32 mask) +{ + u8 isr; + u32 val = 0; + + switch (off) { + case offsetof(struct virtio_pci_mmio, cfg.device_feature_select): + case offsetof(struct virtio_pci_mmio, cfg.device_feature): + case offsetof(struct virtio_pci_mmio, cfg.guest_feature_select): + case offsetof(struct virtio_pci_mmio, cfg.guest_feature): + /* + * 3.1.1: + * + * The driver MUST follow this sequence to initialize a device: + *... + * - Set the DRIVER status bit: the guest OS knows how + * to drive the device. + * - Read device feature bits, and write the subset + * of feature bits understood by the OS and driver + * to the device. + */ + if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER)) + bad_driver(d, + "feature read before VIRTIO_CONFIG_S_DRIVER"); + goto read_through32; + case offsetof(struct virtio_pci_mmio, cfg.msix_config): + bad_driver(d, "read of msix_config"); + case offsetof(struct virtio_pci_mmio, cfg.num_queues): + goto read_through16; + case offsetof(struct virtio_pci_mmio, cfg.device_status): + /* As they did read, any write of FEATURES_OK is now fine. */ + d->wrote_features_ok = false; + goto read_through8; + case offsetof(struct virtio_pci_mmio, cfg.config_generation): + /* + * 4.1.4.3.1: + * + * The device MUST present a changed config_generation after + * the driver has read a device-specific configuration value + * which has changed since any part of the device-specific + * configuration was last read. + * + * This is simple: none of our devices change config, so this + * is always 0. + */ + goto read_through8; + case offsetof(struct virtio_pci_mmio, notify): + /* + * 3.1.1: + * + * The driver MUST NOT notify the device before setting + * DRIVER_OK. + */ + if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER_OK)) + bad_driver(d, "notify before VIRTIO_CONFIG_S_DRIVER_OK"); + goto read_through16; + case offsetof(struct virtio_pci_mmio, isr): + if (mask != 0xFF) + bad_driver(d, "non-8-bit read from offset %u (%#x)", + off, getreg(eip)); + isr = d->mmio->isr; + /* + * 4.1.4.5.1: + * + * The device MUST reset ISR status to 0 on driver read. + */ + d->mmio->isr = 0; + return isr; + case offsetof(struct virtio_pci_mmio, padding): + bad_driver(d, "read from padding (%#x)", getreg(eip)); + default: + /* Read from device config space, beware unaligned overflow */ + if (off > d->mmio_size - 4) + bad_driver(d, "read past end (%#x)", getreg(eip)); + + /* + * 3.1.1: + * The driver MUST follow this sequence to initialize a device: + *... + * 3. Set the DRIVER status bit: the guest OS knows how to + * drive the device. + * 4. Read device feature bits, and write the subset of + * feature bits understood by the OS and driver to the + * device. During this step the driver MAY read (but MUST NOT + * write) the device-specific configuration fields to check + * that it can support the device before accepting it. + */ + if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER)) + bad_driver(d, + "config read before VIRTIO_CONFIG_S_DRIVER"); + + if (mask == 0xFFFFFFFF) + goto read_through32; + else if (mask == 0xFFFF) + goto read_through16; + else + goto read_through8; + } + + /* + * 4.1.3.1: + * + * The driver MUST access each field using the “natural” access + * method, i.e. 32-bit accesses for 32-bit fields, 16-bit accesses for + * 16-bit fields and 8-bit accesses for 8-bit fields. + */ +read_through32: + if (mask != 0xFFFFFFFF) + bad_driver(d, "non-32-bit read to offset %u (%#x)", + off, getreg(eip)); + memcpy(&val, (char *)d->mmio + off, 4); + return val; + +read_through16: + if (mask != 0xFFFF) + bad_driver(d, "non-16-bit read to offset %u (%#x)", + off, getreg(eip)); + memcpy(&val, (char *)d->mmio + off, 2); + return val; + +read_through8: + if (mask != 0xFF) + bad_driver(d, "non-8-bit read to offset %u (%#x)", + off, getreg(eip)); + memcpy(&val, (char *)d->mmio + off, 1); + return val; +} + +static void emulate_mmio(unsigned long paddr, const u8 *insn) +{ + u32 val, off, mask = 0xFFFFFFFF, insnlen = 0; + struct device *d = find_mmio_region(paddr, &off); + unsigned long args[] = { LHREQ_TRAP, 14 }; + + if (!d) { + warnx("MMIO touching %#08lx (not a device)", paddr); + goto reinject; + } + + /* Prefix makes it a 16 bit op */ + if (insn[0] == 0x66) { + mask = 0xFFFF; + insnlen++; + } + + /* iowrite */ + if (insn[insnlen] == 0x89) { + /* Next byte is r/m byte: bits 3-5 are register. */ + val = getreg_num((insn[insnlen+1] >> 3) & 0x7, mask); + emulate_mmio_write(d, off, val, mask); + insnlen += 2 + insn_displacement_len(insn[insnlen+1]); + } else if (insn[insnlen] == 0x8b) { /* ioread */ + /* Next byte is r/m byte: bits 3-5 are register. */ + val = emulate_mmio_read(d, off, mask); + setreg_num((insn[insnlen+1] >> 3) & 0x7, val, mask); + insnlen += 2 + insn_displacement_len(insn[insnlen+1]); + } else if (insn[0] == 0x88) { /* 8-bit iowrite */ + mask = 0xff; + /* Next byte is r/m byte: bits 3-5 are register. */ + val = getreg_num((insn[1] >> 3) & 0x7, mask); + emulate_mmio_write(d, off, val, mask); + insnlen = 2 + insn_displacement_len(insn[1]); + } else if (insn[0] == 0x8a) { /* 8-bit ioread */ + mask = 0xff; + val = emulate_mmio_read(d, off, mask); + setreg_num((insn[1] >> 3) & 0x7, val, mask); + insnlen = 2 + insn_displacement_len(insn[1]); + } else { + warnx("Unknown MMIO instruction touching %#08lx:" + " %02x %02x %02x %02x at %u", + paddr, insn[0], insn[1], insn[2], insn[3], getreg(eip)); + reinject: + /* Inject trap into Guest. */ + if (write(lguest_fd, args, sizeof(args)) < 0) + err(1, "Reinjecting trap 14 for fault at %#x", + getreg(eip)); + return; + } + + /* Finally, we've "done" the instruction, so move past it. */ + setreg(eip, getreg(eip) + insnlen); +} + +/*L:190 + * Device Setup + * + * All devices need a descriptor so the Guest knows it exists, and a "struct + * device" so the Launcher can keep track of it. We have common helper + * routines to allocate and manage them. + */ +static void add_pci_virtqueue(struct device *dev, + void (*service)(struct virtqueue *), + const char *name) +{ + struct virtqueue **i, *vq = malloc(sizeof(*vq)); + + /* Initialize the virtqueue */ + vq->next = NULL; + vq->last_avail_idx = 0; + vq->dev = dev; + vq->name = name; + + /* + * This is the routine the service thread will run, and its Process ID + * once it's running. + */ + vq->service = service; + vq->thread = (pid_t)-1; + + /* Initialize the configuration. */ + reset_vq_pci_config(vq); + vq->pci_config.queue_notify_off = 0; + + /* Add one to the number of queues */ + vq->dev->mmio->cfg.num_queues++; + + /* + * Add to tail of list, so dev->vq is first vq, dev->vq->next is + * second. + */ + for (i = &dev->vq; *i; i = &(*i)->next); + *i = vq; +} + +/* The Guest accesses the feature bits via the PCI common config MMIO region */ +static void add_pci_feature(struct device *dev, unsigned bit) +{ + dev->features |= (1ULL << bit); +} + +/* For devices with no config. */ +static void no_device_config(struct device *dev) +{ + dev->mmio_addr = get_mmio_region(dev->mmio_size); + + dev->config.bar[0] = dev->mmio_addr; + /* Bottom 4 bits must be zero */ + assert(~(dev->config.bar[0] & 0xF)); +} + +/* This puts the device config into BAR0 */ +static void set_device_config(struct device *dev, const void *conf, size_t len) +{ + /* Set up BAR 0 */ + dev->mmio_size += len; + dev->mmio = realloc(dev->mmio, dev->mmio_size); + memcpy(dev->mmio + 1, conf, len); + + /* + * 4.1.4.6: + * + * The device MUST present at least one VIRTIO_PCI_CAP_DEVICE_CFG + * capability for any device type which has a device-specific + * configuration. + */ + /* Hook up device cfg */ + dev->config.cfg_access.cap.cap_next + = offsetof(struct pci_config, device); + + /* + * 4.1.4.6.1: + * + * The offset for the device-specific configuration MUST be 4-byte + * aligned. + */ + assert(dev->config.cfg_access.cap.cap_next % 4 == 0); + + /* Fix up device cfg field length. */ + dev->config.device.length = len; + + /* The rest is the same as the no-config case */ + no_device_config(dev); +} + +static void init_cap(struct virtio_pci_cap *cap, size_t caplen, int type, + size_t bar_offset, size_t bar_bytes, u8 next) +{ + cap->cap_vndr = PCI_CAP_ID_VNDR; + cap->cap_next = next; + cap->cap_len = caplen; + cap->cfg_type = type; + cap->bar = 0; + memset(cap->padding, 0, sizeof(cap->padding)); + cap->offset = bar_offset; + cap->length = bar_bytes; +} + +/* + * This sets up the pci_config structure, as defined in the virtio 1.0 + * standard (and PCI standard). + */ +static void init_pci_config(struct pci_config *pci, u16 type, + u8 class, u8 subclass) +{ + size_t bar_offset, bar_len; + + /* + * 4.1.4.4.1: + * + * The device MUST either present notify_off_multiplier as an even + * power of 2, or present notify_off_multiplier as 0. + * + * 2.1.2: + * + * The device MUST initialize device status to 0 upon reset. + */ + memset(pci, 0, sizeof(*pci)); + + /* 4.1.2.1: Devices MUST have the PCI Vendor ID 0x1AF4 */ + pci->vendor_id = 0x1AF4; + /* 4.1.2.1: ... PCI Device ID calculated by adding 0x1040 ... */ + pci->device_id = 0x1040 + type; + + /* + * PCI have specific codes for different types of devices. + * Linux doesn't care, but it's a good clue for people looking + * at the device. + */ + pci->class = class; + pci->subclass = subclass; + + /* + * 4.1.2.1: + * + * Non-transitional devices SHOULD have a PCI Revision ID of 1 or + * higher + */ + pci->revid = 1; + + /* + * 4.1.2.1: + * + * Non-transitional devices SHOULD have a PCI Subsystem Device ID of + * 0x40 or higher. + */ + pci->subsystem_device_id = 0x40; + + /* We use our dummy interrupt controller, and irq_line is the irq */ + pci->irq_line = devices.next_irq++; + pci->irq_pin = 0; + + /* Support for extended capabilities. */ + pci->status = (1 << 4); + + /* Link them in. */ + /* + * 4.1.4.3.1: + * + * The device MUST present at least one common configuration + * capability. + */ + pci->capabilities = offsetof(struct pci_config, common); + + /* 4.1.4.3.1 ... offset MUST be 4-byte aligned. */ + assert(pci->capabilities % 4 == 0); + + bar_offset = offsetof(struct virtio_pci_mmio, cfg); + bar_len = sizeof(((struct virtio_pci_mmio *)0)->cfg); + init_cap(&pci->common, sizeof(pci->common), VIRTIO_PCI_CAP_COMMON_CFG, + bar_offset, bar_len, + offsetof(struct pci_config, notify)); + + /* + * 4.1.4.4.1: + * + * The device MUST present at least one notification capability. + */ + bar_offset += bar_len; + bar_len = sizeof(((struct virtio_pci_mmio *)0)->notify); + + /* + * 4.1.4.4.1: + * + * The cap.offset MUST be 2-byte aligned. + */ + assert(pci->common.cap_next % 2 == 0); + + /* FIXME: Use a non-zero notify_off, for per-queue notification? */ + /* + * 4.1.4.4.1: + * + * The value cap.length presented by the device MUST be at least 2 and + * MUST be large enough to support queue notification offsets for all + * supported queues in all possible configurations. + */ + assert(bar_len >= 2); + + init_cap(&pci->notify.cap, sizeof(pci->notify), + VIRTIO_PCI_CAP_NOTIFY_CFG, + bar_offset, bar_len, + offsetof(struct pci_config, isr)); + + bar_offset += bar_len; + bar_len = sizeof(((struct virtio_pci_mmio *)0)->isr); + /* + * 4.1.4.5.1: + * + * The device MUST present at least one VIRTIO_PCI_CAP_ISR_CFG + * capability. + */ + init_cap(&pci->isr, sizeof(pci->isr), + VIRTIO_PCI_CAP_ISR_CFG, + bar_offset, bar_len, + offsetof(struct pci_config, cfg_access)); + + /* + * 4.1.4.7.1: + * + * The device MUST present at least one VIRTIO_PCI_CAP_PCI_CFG + * capability. + */ + /* This doesn't have any presence in the BAR */ + init_cap(&pci->cfg_access.cap, sizeof(pci->cfg_access), + VIRTIO_PCI_CAP_PCI_CFG, + 0, 0, 0); + + bar_offset += bar_len + sizeof(((struct virtio_pci_mmio *)0)->padding); + assert(bar_offset == sizeof(struct virtio_pci_mmio)); + + /* + * This gets sewn in and length set in set_device_config(). + * Some devices don't have a device configuration interface, so + * we never expose this if we don't call set_device_config(). + */ + init_cap(&pci->device, sizeof(pci->device), VIRTIO_PCI_CAP_DEVICE_CFG, + bar_offset, 0, 0); +} + +/* + * This routine does all the creation and setup of a new device, but we don't + * actually place the MMIO region until we know the size (if any) of the + * device-specific config. And we don't actually start the service threads + * until later. + * + * See what I mean about userspace being boring? + */ +static struct device *new_pci_device(const char *name, u16 type, + u8 class, u8 subclass) +{ + struct device *dev = malloc(sizeof(*dev)); + + /* Now we populate the fields one at a time. */ + dev->name = name; + dev->vq = NULL; + dev->running = false; + dev->wrote_features_ok = false; + dev->mmio_size = sizeof(struct virtio_pci_mmio); + dev->mmio = calloc(1, dev->mmio_size); + dev->features = (u64)1 << VIRTIO_F_VERSION_1; + dev->features_accepted = 0; + + if (devices.device_num + 1 >= MAX_PCI_DEVICES) + errx(1, "Can only handle 31 PCI devices"); + + init_pci_config(&dev->config, type, class, subclass); + assert(!devices.pci[devices.device_num+1]); + devices.pci[++devices.device_num] = dev; + + return dev; +} + +/* + * Our first setup routine is the console. It's a fairly simple device, but + * UNIX tty handling makes it uglier than it could be. + */ +static void setup_console(void) +{ + struct device *dev; + struct virtio_console_config conf; + + /* If we can save the initial standard input settings... */ + if (tcgetattr(STDIN_FILENO, &orig_term) == 0) { + struct termios term = orig_term; + /* + * Then we turn off echo, line buffering and ^C etc: We want a + * raw input stream to the Guest. + */ + term.c_lflag &= ~(ISIG|ICANON|ECHO); + tcsetattr(STDIN_FILENO, TCSANOW, &term); + } + + dev = new_pci_device("console", VIRTIO_ID_CONSOLE, 0x07, 0x00); + + /* We store the console state in dev->priv, and initialize it. */ + dev->priv = malloc(sizeof(struct console_abort)); + ((struct console_abort *)dev->priv)->count = 0; + + /* + * The console needs two virtqueues: the input then the output. When + * they put something the input queue, we make sure we're listening to + * stdin. When they put something in the output queue, we write it to + * stdout. + */ + add_pci_virtqueue(dev, console_input, "input"); + add_pci_virtqueue(dev, console_output, "output"); + + /* We need a configuration area for the emerg_wr early writes. */ + add_pci_feature(dev, VIRTIO_CONSOLE_F_EMERG_WRITE); + set_device_config(dev, &conf, sizeof(conf)); + + verbose("device %u: console\n", devices.device_num); +} +/*:*/ + +/*M:010 + * Inter-guest networking is an interesting area. Simplest is to have a + * --sharenet=<name> option which opens or creates a named pipe. This can be + * used to send packets to another guest in a 1:1 manner. + * + * More sophisticated is to use one of the tools developed for project like UML + * to do networking. + * + * Faster is to do virtio bonding in kernel. Doing this 1:1 would be + * completely generic ("here's my vring, attach to your vring") and would work + * for any traffic. Of course, namespace and permissions issues need to be + * dealt with. A more sophisticated "multi-channel" virtio_net.c could hide + * multiple inter-guest channels behind one interface, although it would + * require some manner of hotplugging new virtio channels. + * + * Finally, we could use a virtio network switch in the kernel, ie. vhost. +:*/ + +static u32 str2ip(const char *ipaddr) +{ + unsigned int b[4]; + + if (sscanf(ipaddr, "%u.%u.%u.%u", &b[0], &b[1], &b[2], &b[3]) != 4) + errx(1, "Failed to parse IP address '%s'", ipaddr); + return (b[0] << 24) | (b[1] << 16) | (b[2] << 8) | b[3]; +} + +static void str2mac(const char *macaddr, unsigned char mac[6]) +{ + unsigned int m[6]; + if (sscanf(macaddr, "%02x:%02x:%02x:%02x:%02x:%02x", + &m[0], &m[1], &m[2], &m[3], &m[4], &m[5]) != 6) + errx(1, "Failed to parse mac address '%s'", macaddr); + mac[0] = m[0]; + mac[1] = m[1]; + mac[2] = m[2]; + mac[3] = m[3]; + mac[4] = m[4]; + mac[5] = m[5]; +} + +/* + * This code is "adapted" from libbridge: it attaches the Host end of the + * network device to the bridge device specified by the command line. + * + * This is yet another James Morris contribution (I'm an IP-level guy, so I + * dislike bridging), and I just try not to break it. + */ +static void add_to_bridge(int fd, const char *if_name, const char *br_name) +{ + int ifidx; + struct ifreq ifr; + + if (!*br_name) + errx(1, "must specify bridge name"); + + ifidx = if_nametoindex(if_name); + if (!ifidx) + errx(1, "interface %s does not exist!", if_name); + + strncpy(ifr.ifr_name, br_name, IFNAMSIZ); + ifr.ifr_name[IFNAMSIZ-1] = '\0'; + ifr.ifr_ifindex = ifidx; + if (ioctl(fd, SIOCBRADDIF, &ifr) < 0) + err(1, "can't add %s to bridge %s", if_name, br_name); +} + +/* + * This sets up the Host end of the network device with an IP address, brings + * it up so packets will flow, the copies the MAC address into the hwaddr + * pointer. + */ +static void configure_device(int fd, const char *tapif, u32 ipaddr) +{ + struct ifreq ifr; + struct sockaddr_in sin; + + memset(&ifr, 0, sizeof(ifr)); + strcpy(ifr.ifr_name, tapif); + + /* Don't read these incantations. Just cut & paste them like I did! */ + sin.sin_family = AF_INET; + sin.sin_addr.s_addr = htonl(ipaddr); + memcpy(&ifr.ifr_addr, &sin, sizeof(sin)); + if (ioctl(fd, SIOCSIFADDR, &ifr) != 0) + err(1, "Setting %s interface address", tapif); + ifr.ifr_flags = IFF_UP; + if (ioctl(fd, SIOCSIFFLAGS, &ifr) != 0) + err(1, "Bringing interface %s up", tapif); +} + +static int get_tun_device(char tapif[IFNAMSIZ]) +{ + struct ifreq ifr; + int vnet_hdr_sz; + int netfd; + + /* Start with this zeroed. Messy but sure. */ + memset(&ifr, 0, sizeof(ifr)); + + /* + * We open the /dev/net/tun device and tell it we want a tap device. A + * tap device is like a tun device, only somehow different. To tell + * the truth, I completely blundered my way through this code, but it + * works now! + */ + netfd = open_or_die("/dev/net/tun", O_RDWR); + ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_VNET_HDR; + strcpy(ifr.ifr_name, "tap%d"); + if (ioctl(netfd, TUNSETIFF, &ifr) != 0) + err(1, "configuring /dev/net/tun"); + + if (ioctl(netfd, TUNSETOFFLOAD, + TUN_F_CSUM|TUN_F_TSO4|TUN_F_TSO6|TUN_F_TSO_ECN) != 0) + err(1, "Could not set features for tun device"); + + /* + * We don't need checksums calculated for packets coming in this + * device: trust us! + */ + ioctl(netfd, TUNSETNOCSUM, 1); + + /* + * In virtio before 1.0 (aka legacy virtio), we added a 16-bit + * field at the end of the network header iff + * VIRTIO_NET_F_MRG_RXBUF was negotiated. For virtio 1.0, + * that became the norm, but we need to tell the tun device + * about our expanded header (which is called + * virtio_net_hdr_mrg_rxbuf in the legacy system). + */ + vnet_hdr_sz = sizeof(struct virtio_net_hdr_v1); + if (ioctl(netfd, TUNSETVNETHDRSZ, &vnet_hdr_sz) != 0) + err(1, "Setting tun header size to %u", vnet_hdr_sz); + + memcpy(tapif, ifr.ifr_name, IFNAMSIZ); + return netfd; +} + +/*L:195 + * Our network is a Host<->Guest network. This can either use bridging or + * routing, but the principle is the same: it uses the "tun" device to inject + * packets into the Host as if they came in from a normal network card. We + * just shunt packets between the Guest and the tun device. + */ +static void setup_tun_net(char *arg) +{ + struct device *dev; + struct net_info *net_info = malloc(sizeof(*net_info)); + int ipfd; + u32 ip = INADDR_ANY; + bool bridging = false; + char tapif[IFNAMSIZ], *p; + struct virtio_net_config conf; + + net_info->tunfd = get_tun_device(tapif); + + /* First we create a new network device. */ + dev = new_pci_device("net", VIRTIO_ID_NET, 0x02, 0x00); + dev->priv = net_info; + + /* Network devices need a recv and a send queue, just like console. */ + add_pci_virtqueue(dev, net_input, "rx"); + add_pci_virtqueue(dev, net_output, "tx"); + + /* + * We need a socket to perform the magic network ioctls to bring up the + * tap interface, connect to the bridge etc. Any socket will do! + */ + ipfd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP); + if (ipfd < 0) + err(1, "opening IP socket"); + + /* If the command line was --tunnet=bridge:<name> do bridging. */ + if (!strncmp(BRIDGE_PFX, arg, strlen(BRIDGE_PFX))) { + arg += strlen(BRIDGE_PFX); + bridging = true; + } + + /* A mac address may follow the bridge name or IP address */ + p = strchr(arg, ':'); + if (p) { + str2mac(p+1, conf.mac); + add_pci_feature(dev, VIRTIO_NET_F_MAC); + *p = '\0'; + } + + /* arg is now either an IP address or a bridge name */ + if (bridging) + add_to_bridge(ipfd, tapif, arg); + else + ip = str2ip(arg); + + /* Set up the tun device. */ + configure_device(ipfd, tapif, ip); + + /* Expect Guest to handle everything except UFO */ + add_pci_feature(dev, VIRTIO_NET_F_CSUM); + add_pci_feature(dev, VIRTIO_NET_F_GUEST_CSUM); + add_pci_feature(dev, VIRTIO_NET_F_GUEST_TSO4); + add_pci_feature(dev, VIRTIO_NET_F_GUEST_TSO6); + add_pci_feature(dev, VIRTIO_NET_F_GUEST_ECN); + add_pci_feature(dev, VIRTIO_NET_F_HOST_TSO4); + add_pci_feature(dev, VIRTIO_NET_F_HOST_TSO6); + add_pci_feature(dev, VIRTIO_NET_F_HOST_ECN); + /* We handle indirect ring entries */ + add_pci_feature(dev, VIRTIO_RING_F_INDIRECT_DESC); + set_device_config(dev, &conf, sizeof(conf)); + + /* We don't need the socket any more; setup is done. */ + close(ipfd); + + if (bridging) + verbose("device %u: tun %s attached to bridge: %s\n", + devices.device_num, tapif, arg); + else + verbose("device %u: tun %s: %s\n", + devices.device_num, tapif, arg); +} +/*:*/ + +/* This hangs off device->priv. */ +struct vblk_info { + /* The size of the file. */ + off64_t len; + + /* The file descriptor for the file. */ + int fd; + +}; + +/*L:210 + * The Disk + * + * The disk only has one virtqueue, so it only has one thread. It is really + * simple: the Guest asks for a block number and we read or write that position + * in the file. + * + * Before we serviced each virtqueue in a separate thread, that was unacceptably + * slow: the Guest waits until the read is finished before running anything + * else, even if it could have been doing useful work. + * + * We could have used async I/O, except it's reputed to suck so hard that + * characters actually go missing from your code when you try to use it. + */ +static void blk_request(struct virtqueue *vq) +{ + struct vblk_info *vblk = vq->dev->priv; + unsigned int head, out_num, in_num, wlen; + int ret, i; + u8 *in; + struct virtio_blk_outhdr out; + struct iovec iov[vq->vring.num]; + off64_t off; + + /* + * Get the next request, where we normally wait. It triggers the + * interrupt to acknowledge previously serviced requests (if any). + */ + head = wait_for_vq_desc(vq, iov, &out_num, &in_num); + + /* Copy the output header from the front of the iov (adjusts iov) */ + iov_consume(vq->dev, iov, out_num, &out, sizeof(out)); + + /* Find and trim end of iov input array, for our status byte. */ + in = NULL; + for (i = out_num + in_num - 1; i >= out_num; i--) { + if (iov[i].iov_len > 0) { + in = iov[i].iov_base + iov[i].iov_len - 1; + iov[i].iov_len--; + break; + } + } + if (!in) + bad_driver_vq(vq, "Bad virtblk cmd with no room for status"); + + /* + * For historical reasons, block operations are expressed in 512 byte + * "sectors". + */ + off = out.sector * 512; + + if (out.type & VIRTIO_BLK_T_OUT) { + /* + * Write + * + * Move to the right location in the block file. This can fail + * if they try to write past end. + */ + if (lseek64(vblk->fd, off, SEEK_SET) != off) + err(1, "Bad seek to sector %llu", out.sector); + + ret = writev(vblk->fd, iov, out_num); + verbose("WRITE to sector %llu: %i\n", out.sector, ret); + + /* + * Grr... Now we know how long the descriptor they sent was, we + * make sure they didn't try to write over the end of the block + * file (possibly extending it). + */ + if (ret > 0 && off + ret > vblk->len) { + /* Trim it back to the correct length */ + ftruncate64(vblk->fd, vblk->len); + /* Die, bad Guest, die. */ + bad_driver_vq(vq, "Write past end %llu+%u", off, ret); + } + + wlen = sizeof(*in); + *in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR); + } else if (out.type & VIRTIO_BLK_T_FLUSH) { + /* Flush */ + ret = fdatasync(vblk->fd); + verbose("FLUSH fdatasync: %i\n", ret); + wlen = sizeof(*in); + *in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR); + } else { + /* + * Read + * + * Move to the right location in the block file. This can fail + * if they try to read past end. + */ + if (lseek64(vblk->fd, off, SEEK_SET) != off) + err(1, "Bad seek to sector %llu", out.sector); + + ret = readv(vblk->fd, iov + out_num, in_num); + if (ret >= 0) { + wlen = sizeof(*in) + ret; + *in = VIRTIO_BLK_S_OK; + } else { + wlen = sizeof(*in); + *in = VIRTIO_BLK_S_IOERR; + } + } + + /* Finished that request. */ + add_used(vq, head, wlen); +} + +/*L:198 This actually sets up a virtual block device. */ +static void setup_block_file(const char *filename) +{ + struct device *dev; + struct vblk_info *vblk; + struct virtio_blk_config conf; + + /* Create the device. */ + dev = new_pci_device("block", VIRTIO_ID_BLOCK, 0x01, 0x80); + + /* The device has one virtqueue, where the Guest places requests. */ + add_pci_virtqueue(dev, blk_request, "request"); + + /* Allocate the room for our own bookkeeping */ + vblk = dev->priv = malloc(sizeof(*vblk)); + + /* First we open the file and store the length. */ + vblk->fd = open_or_die(filename, O_RDWR|O_LARGEFILE); + vblk->len = lseek64(vblk->fd, 0, SEEK_END); + + /* Tell Guest how many sectors this device has. */ + conf.capacity = cpu_to_le64(vblk->len / 512); + + /* + * Tell Guest not to put in too many descriptors at once: two are used + * for the in and out elements. + */ + add_pci_feature(dev, VIRTIO_BLK_F_SEG_MAX); + conf.seg_max = cpu_to_le32(VIRTQUEUE_NUM - 2); + + set_device_config(dev, &conf, sizeof(struct virtio_blk_config)); + + verbose("device %u: virtblock %llu sectors\n", + devices.device_num, le64_to_cpu(conf.capacity)); +} + +/*L:211 + * Our random number generator device reads from /dev/urandom into the Guest's + * input buffers. The usual case is that the Guest doesn't want random numbers + * and so has no buffers although /dev/urandom is still readable, whereas + * console is the reverse. + * + * The same logic applies, however. + */ +struct rng_info { + int rfd; +}; + +static void rng_input(struct virtqueue *vq) +{ + int len; + unsigned int head, in_num, out_num, totlen = 0; + struct rng_info *rng_info = vq->dev->priv; + struct iovec iov[vq->vring.num]; + + /* First we need a buffer from the Guests's virtqueue. */ + head = wait_for_vq_desc(vq, iov, &out_num, &in_num); + if (out_num) + bad_driver_vq(vq, "Output buffers in rng?"); + + /* + * Just like the console write, we loop to cover the whole iovec. + * In this case, short reads actually happen quite a bit. + */ + while (!iov_empty(iov, in_num)) { + len = readv(rng_info->rfd, iov, in_num); + if (len <= 0) + err(1, "Read from /dev/urandom gave %i", len); + iov_consume(vq->dev, iov, in_num, NULL, len); + totlen += len; + } + + /* Tell the Guest about the new input. */ + add_used(vq, head, totlen); +} + +/*L:199 + * This creates a "hardware" random number device for the Guest. + */ +static void setup_rng(void) +{ + struct device *dev; + struct rng_info *rng_info = malloc(sizeof(*rng_info)); + + /* Our device's private info simply contains the /dev/urandom fd. */ + rng_info->rfd = open_or_die("/dev/urandom", O_RDONLY); + + /* Create the new device. */ + dev = new_pci_device("rng", VIRTIO_ID_RNG, 0xff, 0); + dev->priv = rng_info; + + /* The device has one virtqueue, where the Guest places inbufs. */ + add_pci_virtqueue(dev, rng_input, "input"); + + /* We don't have any configuration space */ + no_device_config(dev); + + verbose("device %u: rng\n", devices.device_num); +} +/* That's the end of device setup. */ + +/*L:230 Reboot is pretty easy: clean up and exec() the Launcher afresh. */ +static void __attribute__((noreturn)) restart_guest(void) +{ + unsigned int i; + + /* + * Since we don't track all open fds, we simply close everything beyond + * stderr. + */ + for (i = 3; i < FD_SETSIZE; i++) + close(i); + + /* Reset all the devices (kills all threads). */ + cleanup_devices(); + + execv(main_args[0], main_args); + err(1, "Could not exec %s", main_args[0]); +} + +/*L:220 + * Finally we reach the core of the Launcher which runs the Guest, serves + * its input and output, and finally, lays it to rest. + */ +static void __attribute__((noreturn)) run_guest(void) +{ + for (;;) { + struct lguest_pending notify; + int readval; + + /* We read from the /dev/lguest device to run the Guest. */ + readval = pread(lguest_fd, ¬ify, sizeof(notify), cpu_id); + if (readval == sizeof(notify)) { + if (notify.trap == 13) { + verbose("Emulating instruction at %#x\n", + getreg(eip)); + emulate_insn(notify.insn); + } else if (notify.trap == 14) { + verbose("Emulating MMIO at %#x\n", + getreg(eip)); + emulate_mmio(notify.addr, notify.insn); + } else + errx(1, "Unknown trap %i addr %#08x\n", + notify.trap, notify.addr); + /* ENOENT means the Guest died. Reading tells us why. */ + } else if (errno == ENOENT) { + char reason[1024] = { 0 }; + pread(lguest_fd, reason, sizeof(reason)-1, cpu_id); + errx(1, "%s", reason); + /* ERESTART means that we need to reboot the guest */ + } else if (errno == ERESTART) { + restart_guest(); + /* Anything else means a bug or incompatible change. */ + } else + err(1, "Running guest failed"); + } +} +/*L:240 + * This is the end of the Launcher. The good news: we are over halfway + * through! The bad news: the most fiendish part of the code still lies ahead + * of us. + * + * Are you ready? Take a deep breath and join me in the core of the Host, in + * "make Host". +:*/ + +static struct option opts[] = { + { "verbose", 0, NULL, 'v' }, + { "tunnet", 1, NULL, 't' }, + { "block", 1, NULL, 'b' }, + { "rng", 0, NULL, 'r' }, + { "initrd", 1, NULL, 'i' }, + { "username", 1, NULL, 'u' }, + { "chroot", 1, NULL, 'c' }, + { NULL }, +}; +static void usage(void) +{ + errx(1, "Usage: lguest [--verbose] " + "[--tunnet=(<ipaddr>:<macaddr>|bridge:<bridgename>:<macaddr>)\n" + "|--block=<filename>|--initrd=<filename>]...\n" + "<mem-in-mb> vmlinux [args...]"); +} + +/*L:105 The main routine is where the real work begins: */ +int main(int argc, char *argv[]) +{ + /* Memory, code startpoint and size of the (optional) initrd. */ + unsigned long mem = 0, start, initrd_size = 0; + /* Two temporaries. */ + int i, c; + /* The boot information for the Guest. */ + struct boot_params *boot; + /* If they specify an initrd file to load. */ + const char *initrd_name = NULL; + + /* Password structure for initgroups/setres[gu]id */ + struct passwd *user_details = NULL; + + /* Directory to chroot to */ + char *chroot_path = NULL; + + /* Save the args: we "reboot" by execing ourselves again. */ + main_args = argv; + + /* + * First we initialize the device list. We remember next interrupt + * number to use for devices (1: remember that 0 is used by the timer). + */ + devices.next_irq = 1; + + /* We're CPU 0. In fact, that's the only CPU possible right now. */ + cpu_id = 0; + + /* + * We need to know how much memory so we can set up the device + * descriptor and memory pages for the devices as we parse the command + * line. So we quickly look through the arguments to find the amount + * of memory now. + */ + for (i = 1; i < argc; i++) { + if (argv[i][0] != '-') { + mem = atoi(argv[i]) * 1024 * 1024; + /* + * We start by mapping anonymous pages over all of + * guest-physical memory range. This fills it with 0, + * and ensures that the Guest won't be killed when it + * tries to access it. + */ + guest_base = map_zeroed_pages(mem / getpagesize() + + DEVICE_PAGES); + guest_limit = mem; + guest_max = guest_mmio = mem + DEVICE_PAGES*getpagesize(); + break; + } + } + + /* We always have a console device, and it's always device 1. */ + setup_console(); + + /* The options are fairly straight-forward */ + while ((c = getopt_long(argc, argv, "v", opts, NULL)) != EOF) { + switch (c) { + case 'v': + verbose = true; + break; + case 't': + setup_tun_net(optarg); + break; + case 'b': + setup_block_file(optarg); + break; + case 'r': + setup_rng(); + break; + case 'i': + initrd_name = optarg; + break; + case 'u': + user_details = getpwnam(optarg); + if (!user_details) + err(1, "getpwnam failed, incorrect username?"); + break; + case 'c': + chroot_path = optarg; + break; + default: + warnx("Unknown argument %s", argv[optind]); + usage(); + } + } + /* + * After the other arguments we expect memory and kernel image name, + * followed by command line arguments for the kernel. + */ + if (optind + 2 > argc) + usage(); + + verbose("Guest base is at %p\n", guest_base); + + /* Initialize the (fake) PCI host bridge device. */ + init_pci_host_bridge(); + + /* Now we load the kernel */ + start = load_kernel(open_or_die(argv[optind+1], O_RDONLY)); + + /* Boot information is stashed at physical address 0 */ + boot = from_guest_phys(0); + + /* Map the initrd image if requested (at top of physical memory) */ + if (initrd_name) { + initrd_size = load_initrd(initrd_name, mem); + /* + * These are the location in the Linux boot header where the + * start and size of the initrd are expected to be found. + */ + boot->hdr.ramdisk_image = mem - initrd_size; + boot->hdr.ramdisk_size = initrd_size; + /* The bootloader type 0xFF means "unknown"; that's OK. */ + boot->hdr.type_of_loader = 0xFF; + } + + /* + * The Linux boot header contains an "E820" memory map: ours is a + * simple, single region. + */ + boot->e820_entries = 1; + boot->e820_map[0] = ((struct e820entry) { 0, mem, E820_RAM }); + /* + * The boot header contains a command line pointer: we put the command + * line after the boot header. + */ + boot->hdr.cmd_line_ptr = to_guest_phys(boot + 1); + /* We use a simple helper to copy the arguments separated by spaces. */ + concat((char *)(boot + 1), argv+optind+2); + + /* Set kernel alignment to 16M (CONFIG_PHYSICAL_ALIGN) */ + boot->hdr.kernel_alignment = 0x1000000; + + /* Boot protocol version: 2.07 supports the fields for lguest. */ + boot->hdr.version = 0x207; + + /* The hardware_subarch value of "1" tells the Guest it's an lguest. */ + boot->hdr.hardware_subarch = 1; + + /* Tell the entry path not to try to reload segment registers. */ + boot->hdr.loadflags |= KEEP_SEGMENTS; + + /* We tell the kernel to initialize the Guest. */ + tell_kernel(start); + + /* Ensure that we terminate if a device-servicing child dies. */ + signal(SIGCHLD, kill_launcher); + + /* If we exit via err(), this kills all the threads, restores tty. */ + atexit(cleanup_devices); + + /* If requested, chroot to a directory */ + if (chroot_path) { + if (chroot(chroot_path) != 0) + err(1, "chroot(\"%s\") failed", chroot_path); + + if (chdir("/") != 0) + err(1, "chdir(\"/\") failed"); + + verbose("chroot done\n"); + } + + /* If requested, drop privileges */ + if (user_details) { + uid_t u; + gid_t g; + + u = user_details->pw_uid; + g = user_details->pw_gid; + + if (initgroups(user_details->pw_name, g) != 0) + err(1, "initgroups failed"); + + if (setresgid(g, g, g) != 0) + err(1, "setresgid failed"); + + if (setresuid(u, u, u) != 0) + err(1, "setresuid failed"); + + verbose("Dropping privileges completed\n"); + } + + /* Finally, run the Guest. This doesn't return. */ + run_guest(); +} +/*:*/ + +/*M:999 + * Mastery is done: you now know everything I do. + * + * But surely you have seen code, features and bugs in your wanderings which + * you now yearn to attack? That is the real game, and I look forward to you + * patching and forking lguest into the Your-Name-Here-visor. + * + * Farewell, and good coding! + * Rusty Russell. + */ diff --git a/kernel/tools/lguest/lguest.txt b/kernel/tools/lguest/lguest.txt new file mode 100644 index 000000000..06e1f4649 --- /dev/null +++ b/kernel/tools/lguest/lguest.txt @@ -0,0 +1,125 @@ + __ + (___()'`; Rusty's Remarkably Unreliable Guide to Lguest + /, /` - or, A Young Coder's Illustrated Hypervisor + \\"--\\ http://lguest.ozlabs.org + +Lguest is designed to be a minimal 32-bit x86 hypervisor for the Linux kernel, +for Linux developers and users to experiment with virtualization with the +minimum of complexity. Nonetheless, it should have sufficient features to +make it useful for specific tasks, and, of course, you are encouraged to fork +and enhance it (see drivers/lguest/README). + +Features: + +- Kernel module which runs in a normal kernel. +- Simple I/O model for communication. +- Simple program to create new guests. +- Logo contains cute puppies: http://lguest.ozlabs.org + +Developer features: + +- Fun to hack on. +- No ABI: being tied to a specific kernel anyway, you can change anything. +- Many opportunities for improvement or feature implementation. + +Running Lguest: + +- The easiest way to run lguest is to use same kernel as guest and host. + You can configure them differently, but usually it's easiest not to. + + You will need to configure your kernel with the following options: + + "Processor type and features": + "Paravirtualized guest support" = Y + "Lguest guest support" = Y + "High Memory Support" = off/4GB + "Alignment value to which kernel should be aligned" = 0x100000 + (CONFIG_PARAVIRT=y, CONFIG_LGUEST_GUEST=y, CONFIG_HIGHMEM64G=n and + CONFIG_PHYSICAL_ALIGN=0x100000) + + "Device Drivers": + "Block devices" + "Virtio block driver" = M/Y + "Network device support" + "Universal TUN/TAP device driver support" = M/Y + "Virtio network driver" = M/Y + (CONFIG_VIRTIO_BLK=m, CONFIG_VIRTIO_NET=m and CONFIG_TUN=m) + + "Virtualization" + "Linux hypervisor example code" = M/Y + (CONFIG_LGUEST=m) + +- A tool called "lguest" is available in this directory: type "make" + to build it. If you didn't build your kernel in-tree, use "make + O=<builddir>". + +- Create or find a root disk image. There are several useful ones + around, such as the xm-test tiny root image at + http://xm-test.xensource.com/ramdisks/initrd-1.1-i386.img + + For more serious work, I usually use a distribution ISO image and + install it under qemu, then make multiple copies: + + dd if=/dev/zero of=rootfile bs=1M count=2048 + qemu -cdrom image.iso -hda rootfile -net user -net nic -boot d + + Make sure that you install a getty on /dev/hvc0 if you want to log in on the + console! + +- "modprobe lg" if you built it as a module. + +- Run an lguest as root: + + tools/lguest/lguest 64 vmlinux --tunnet=192.168.19.1 \ + --block=rootfile root=/dev/vda + + Explanation: + 64: the amount of memory to use, in MB. + + vmlinux: the kernel image found in the top of your build directory. You + can also use a standard bzImage. + + --tunnet=192.168.19.1: configures a "tap" device for networking with this + IP address. + + --block=rootfile: a file or block device which becomes /dev/vda + inside the guest. + + root=/dev/vda: this (and anything else on the command line) are + kernel boot parameters. + +- Configuring networking. I usually have the host masquerade, using + "iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE" and "echo 1 > + /proc/sys/net/ipv4/ip_forward". In this example, I would configure + eth0 inside the guest at 192.168.19.2. + + Another method is to bridge the tap device to an external interface + using --tunnet=bridge:<bridgename>, and perhaps run dhcp on the guest + to obtain an IP address. The bridge needs to be configured first: + this option simply adds the tap interface to it. + + A simple example on my system: + + ifconfig eth0 0.0.0.0 + brctl addbr lg0 + ifconfig lg0 up + brctl addif lg0 eth0 + dhclient lg0 + + Then use --tunnet=bridge:lg0 when launching the guest. + + See: + + http://www.linuxfoundation.org/collaborate/workgroups/networking/bridge + + for general information on how to get bridging to work. + +- Random number generation. Using the --rng option will provide a + /dev/hwrng in the guest that will read from the host's /dev/random. + Use this option in conjunction with rng-tools (see ../hw_random.txt) + to provide entropy to the guest kernel's /dev/random. + +There is a helpful mailing list at http://ozlabs.org/mailman/listinfo/lguest + +Good luck! +Rusty Russell rusty@rustcorp.com.au. |