Add qemu 2.4.0

Change-Id: Ic99cbad4b61f8b127b7dc74d04576c0bcbaaf4f5
Signed-off-by: Yang Zhang <yang.z.zhang@intel.com>

1 files changed, 1709 insertions, 0 deletions

diff --git a/qemu/hw/ide/ahci.c b/qemu/hw/ide/ahci.c
new file mode 100644
index 000000000..48749c1dc
--- /dev/null
+++ b/qemu/hw/ide/ahci.c
@@ -0,0 +1,1709 @@
+/*
+ * QEMU AHCI Emulation
+ *
+ * Copyright (c) 2010 qiaochong@loongson.cn
+ * Copyright (c) 2010 Roland Elek <elek.roland@gmail.com>
+ * Copyright (c) 2010 Sebastian Herbszt <herbszt@gmx.de>
+ * Copyright (c) 2010 Alexander Graf <agraf@suse.de>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <hw/hw.h>
+#include <hw/pci/msi.h>
+#include <hw/i386/pc.h>
+#include <hw/pci/pci.h>
+#include <hw/sysbus.h>
+
+#include "qemu/error-report.h"
+#include "sysemu/block-backend.h"
+#include "sysemu/dma.h"
+#include "internal.h"
+#include <hw/ide/pci.h>
+#include <hw/ide/ahci.h>
+
+#define DEBUG_AHCI 0
+
+#define DPRINTF(port, fmt, ...) \
+do { \
+    if (DEBUG_AHCI) { \
+        fprintf(stderr, "ahci: %s: [%d] ", __func__, port); \
+        fprintf(stderr, fmt, ## __VA_ARGS__); \
+    } \
+} while (0)
+
+static void check_cmd(AHCIState *s, int port);
+static int handle_cmd(AHCIState *s, int port, uint8_t slot);
+static void ahci_reset_port(AHCIState *s, int port);
+static void ahci_write_fis_d2h(AHCIDevice *ad, uint8_t *cmd_fis);
+static void ahci_init_d2h(AHCIDevice *ad);
+static int ahci_dma_prepare_buf(IDEDMA *dma, int32_t limit);
+static void ahci_commit_buf(IDEDMA *dma, uint32_t tx_bytes);
+static bool ahci_map_clb_address(AHCIDevice *ad);
+static bool ahci_map_fis_address(AHCIDevice *ad);
+static void ahci_unmap_clb_address(AHCIDevice *ad);
+static void ahci_unmap_fis_address(AHCIDevice *ad);
+
+
+static uint32_t  ahci_port_read(AHCIState *s, int port, int offset)
+{
+    uint32_t val;
+    AHCIPortRegs *pr;
+    pr = &s->dev[port].port_regs;
+
+    switch (offset) {
+    case PORT_LST_ADDR:
+        val = pr->lst_addr;
+        break;
+    case PORT_LST_ADDR_HI:
+        val = pr->lst_addr_hi;
+        break;
+    case PORT_FIS_ADDR:
+        val = pr->fis_addr;
+        break;
+    case PORT_FIS_ADDR_HI:
+        val = pr->fis_addr_hi;
+        break;
+    case PORT_IRQ_STAT:
+        val = pr->irq_stat;
+        break;
+    case PORT_IRQ_MASK:
+        val = pr->irq_mask;
+        break;
+    case PORT_CMD:
+        val = pr->cmd;
+        break;
+    case PORT_TFDATA:
+        val = pr->tfdata;
+        break;
+    case PORT_SIG:
+        val = pr->sig;
+        break;
+    case PORT_SCR_STAT:
+        if (s->dev[port].port.ifs[0].blk) {
+            val = SATA_SCR_SSTATUS_DET_DEV_PRESENT_PHY_UP |
+                  SATA_SCR_SSTATUS_SPD_GEN1 | SATA_SCR_SSTATUS_IPM_ACTIVE;
+        } else {
+            val = SATA_SCR_SSTATUS_DET_NODEV;
+        }
+        break;
+    case PORT_SCR_CTL:
+        val = pr->scr_ctl;
+        break;
+    case PORT_SCR_ERR:
+        val = pr->scr_err;
+        break;
+    case PORT_SCR_ACT:
+        val = pr->scr_act;
+        break;
+    case PORT_CMD_ISSUE:
+        val = pr->cmd_issue;
+        break;
+    case PORT_RESERVED:
+    default:
+        val = 0;
+    }
+    DPRINTF(port, "offset: 0x%x val: 0x%x\n", offset, val);
+    return val;
+
+}
+
+static void ahci_irq_raise(AHCIState *s, AHCIDevice *dev)
+{
+    AHCIPCIState *d = container_of(s, AHCIPCIState, ahci);
+    PCIDevice *pci_dev =
+        (PCIDevice *)object_dynamic_cast(OBJECT(d), TYPE_PCI_DEVICE);
+
+    DPRINTF(0, "raise irq\n");
+
+    if (pci_dev && msi_enabled(pci_dev)) {
+        msi_notify(pci_dev, 0);
+    } else {
+        qemu_irq_raise(s->irq);
+    }
+}
+
+static void ahci_irq_lower(AHCIState *s, AHCIDevice *dev)
+{
+    AHCIPCIState *d = container_of(s, AHCIPCIState, ahci);
+    PCIDevice *pci_dev =
+        (PCIDevice *)object_dynamic_cast(OBJECT(d), TYPE_PCI_DEVICE);
+
+    DPRINTF(0, "lower irq\n");
+
+    if (!pci_dev || !msi_enabled(pci_dev)) {
+        qemu_irq_lower(s->irq);
+    }
+}
+
+static void ahci_check_irq(AHCIState *s)
+{
+    int i;
+
+    DPRINTF(-1, "check irq %#x\n", s->control_regs.irqstatus);
+
+    s->control_regs.irqstatus = 0;
+    for (i = 0; i < s->ports; i++) {
+        AHCIPortRegs *pr = &s->dev[i].port_regs;
+        if (pr->irq_stat & pr->irq_mask) {
+            s->control_regs.irqstatus |= (1 << i);
+        }
+    }
+
+    if (s->control_regs.irqstatus &&
+        (s->control_regs.ghc & HOST_CTL_IRQ_EN)) {
+            ahci_irq_raise(s, NULL);
+    } else {
+        ahci_irq_lower(s, NULL);
+    }
+}
+
+static void ahci_trigger_irq(AHCIState *s, AHCIDevice *d,
+                             int irq_type)
+{
+    DPRINTF(d->port_no, "trigger irq %#x -> %x\n",
+            irq_type, d->port_regs.irq_mask & irq_type);
+
+    d->port_regs.irq_stat |= irq_type;
+    ahci_check_irq(s);
+}
+
+static void map_page(AddressSpace *as, uint8_t **ptr, uint64_t addr,
+                     uint32_t wanted)
+{
+    hwaddr len = wanted;
+
+    if (*ptr) {
+        dma_memory_unmap(as, *ptr, len, DMA_DIRECTION_FROM_DEVICE, len);
+    }
+
+    *ptr = dma_memory_map(as, addr, &len, DMA_DIRECTION_FROM_DEVICE);
+    if (len < wanted) {
+        dma_memory_unmap(as, *ptr, len, DMA_DIRECTION_FROM_DEVICE, len);
+        *ptr = NULL;
+    }
+}
+
+/**
+ * Check the cmd register to see if we should start or stop
+ * the DMA or FIS RX engines.
+ *
+ * @ad: Device to engage.
+ * @allow_stop: Allow device to transition from started to stopped?
+ *   'no' is useful for migration post_load, which does not expect a transition.
+ *
+ * @return 0 on success, -1 on error.
+ */
+static int ahci_cond_start_engines(AHCIDevice *ad, bool allow_stop)
+{
+    AHCIPortRegs *pr = &ad->port_regs;
+
+    if (pr->cmd & PORT_CMD_START) {
+        if (ahci_map_clb_address(ad)) {
+            pr->cmd |= PORT_CMD_LIST_ON;
+        } else {
+            error_report("AHCI: Failed to start DMA engine: "
+                         "bad command list buffer address");
+            return -1;
+        }
+    } else if (pr->cmd & PORT_CMD_LIST_ON) {
+        if (allow_stop) {
+            ahci_unmap_clb_address(ad);
+            pr->cmd = pr->cmd & ~(PORT_CMD_LIST_ON);
+        } else {
+            error_report("AHCI: DMA engine should be off, "
+                         "but appears to still be running");
+            return -1;
+        }
+    }
+
+    if (pr->cmd & PORT_CMD_FIS_RX) {
+        if (ahci_map_fis_address(ad)) {
+            pr->cmd |= PORT_CMD_FIS_ON;
+        } else {
+            error_report("AHCI: Failed to start FIS receive engine: "
+                         "bad FIS receive buffer address");
+            return -1;
+        }
+    } else if (pr->cmd & PORT_CMD_FIS_ON) {
+        if (allow_stop) {
+            ahci_unmap_fis_address(ad);
+            pr->cmd = pr->cmd & ~(PORT_CMD_FIS_ON);
+        } else {
+            error_report("AHCI: FIS receive engine should be off, "
+                         "but appears to still be running");
+            return -1;
+        }
+    }
+
+    return 0;
+}
+
+static void  ahci_port_write(AHCIState *s, int port, int offset, uint32_t val)
+{
+    AHCIPortRegs *pr = &s->dev[port].port_regs;
+
+    DPRINTF(port, "offset: 0x%x val: 0x%x\n", offset, val);
+    switch (offset) {
+        case PORT_LST_ADDR:
+            pr->lst_addr = val;
+            break;
+        case PORT_LST_ADDR_HI:
+            pr->lst_addr_hi = val;
+            break;
+        case PORT_FIS_ADDR:
+            pr->fis_addr = val;
+            break;
+        case PORT_FIS_ADDR_HI:
+            pr->fis_addr_hi = val;
+            break;
+        case PORT_IRQ_STAT:
+            pr->irq_stat &= ~val;
+            ahci_check_irq(s);
+            break;
+        case PORT_IRQ_MASK:
+            pr->irq_mask = val & 0xfdc000ff;
+            ahci_check_irq(s);
+            break;
+        case PORT_CMD:
+            /* Block any Read-only fields from being set;
+             * including LIST_ON and FIS_ON.
+             * The spec requires to set ICC bits to zero after the ICC change
+             * is done. We don't support ICC state changes, therefore always
+             * force the ICC bits to zero.
+             */
+            pr->cmd = (pr->cmd & PORT_CMD_RO_MASK) |
+                      (val & ~(PORT_CMD_RO_MASK|PORT_CMD_ICC_MASK));
+
+            /* Check FIS RX and CLB engines, allow transition to false: */
+            ahci_cond_start_engines(&s->dev[port], true);
+
+            /* XXX usually the FIS would be pending on the bus here and
+                   issuing deferred until the OS enables FIS receival.
+                   Instead, we only submit it once - which works in most
+                   cases, but is a hack. */
+            if ((pr->cmd & PORT_CMD_FIS_ON) &&
+                !s->dev[port].init_d2h_sent) {
+                ahci_init_d2h(&s->dev[port]);
+                s->dev[port].init_d2h_sent = true;
+            }
+
+            check_cmd(s, port);
+            break;
+        case PORT_TFDATA:
+            /* Read Only. */
+            break;
+        case PORT_SIG:
+            /* Read Only */
+            break;
+        case PORT_SCR_STAT:
+            /* Read Only */
+            break;
+        case PORT_SCR_CTL:
+            if (((pr->scr_ctl & AHCI_SCR_SCTL_DET) == 1) &&
+                ((val & AHCI_SCR_SCTL_DET) == 0)) {
+                ahci_reset_port(s, port);
+            }
+            pr->scr_ctl = val;
+            break;
+        case PORT_SCR_ERR:
+            pr->scr_err &= ~val;
+            break;
+        case PORT_SCR_ACT:
+            /* RW1 */
+            pr->scr_act |= val;
+            break;
+        case PORT_CMD_ISSUE:
+            pr->cmd_issue |= val;
+            check_cmd(s, port);
+            break;
+        default:
+            break;
+    }
+}
+
+static uint64_t ahci_mem_read_32(void *opaque, hwaddr addr)
+{
+    AHCIState *s = opaque;
+    uint32_t val = 0;
+
+    if (addr < AHCI_GENERIC_HOST_CONTROL_REGS_MAX_ADDR) {
+        switch (addr) {
+        case HOST_CAP:
+            val = s->control_regs.cap;
+            break;
+        case HOST_CTL:
+            val = s->control_regs.ghc;
+            break;
+        case HOST_IRQ_STAT:
+            val = s->control_regs.irqstatus;
+            break;
+        case HOST_PORTS_IMPL:
+            val = s->control_regs.impl;
+            break;
+        case HOST_VERSION:
+            val = s->control_regs.version;
+            break;
+        }
+
+        DPRINTF(-1, "(addr 0x%08X), val 0x%08X\n", (unsigned) addr, val);
+    } else if ((addr >= AHCI_PORT_REGS_START_ADDR) &&
+               (addr < (AHCI_PORT_REGS_START_ADDR +
+                (s->ports * AHCI_PORT_ADDR_OFFSET_LEN)))) {
+        val = ahci_port_read(s, (addr - AHCI_PORT_REGS_START_ADDR) >> 7,
+                             addr & AHCI_PORT_ADDR_OFFSET_MASK);
+    }
+
+    return val;
+}
+
+
+/**
+ * AHCI 1.3 section 3 ("HBA Memory Registers")
+ * Support unaligned 8/16/32 bit reads, and 64 bit aligned reads.
+ * Caller is responsible for masking unwanted higher order bytes.
+ */
+static uint64_t ahci_mem_read(void *opaque, hwaddr addr, unsigned size)
+{
+    hwaddr aligned = addr & ~0x3;
+    int ofst = addr - aligned;
+    uint64_t lo = ahci_mem_read_32(opaque, aligned);
+    uint64_t hi;
+
+    /* if < 8 byte read does not cross 4 byte boundary */
+    if (ofst + size <= 4) {
+        return lo >> (ofst * 8);
+    }
+    g_assert_cmpint(size, >, 1);
+
+    /* If the 64bit read is unaligned, we will produce undefined
+     * results. AHCI does not support unaligned 64bit reads. */
+    hi = ahci_mem_read_32(opaque, aligned + 4);
+    return (hi << 32 | lo) >> (ofst * 8);
+}
+
+
+static void ahci_mem_write(void *opaque, hwaddr addr,
+                           uint64_t val, unsigned size)
+{
+    AHCIState *s = opaque;
+
+    /* Only aligned reads are allowed on AHCI */
+    if (addr & 3) {
+        fprintf(stderr, "ahci: Mis-aligned write to addr 0x"
+                TARGET_FMT_plx "\n", addr);
+        return;
+    }
+
+    if (addr < AHCI_GENERIC_HOST_CONTROL_REGS_MAX_ADDR) {
+        DPRINTF(-1, "(addr 0x%08X), val 0x%08"PRIX64"\n", (unsigned) addr, val);
+
+        switch (addr) {
+            case HOST_CAP: /* R/WO, RO */
+                /* FIXME handle R/WO */
+                break;
+            case HOST_CTL: /* R/W */
+                if (val & HOST_CTL_RESET) {
+                    DPRINTF(-1, "HBA Reset\n");
+                    ahci_reset(s);
+                } else {
+                    s->control_regs.ghc = (val & 0x3) | HOST_CTL_AHCI_EN;
+                    ahci_check_irq(s);
+                }
+                break;
+            case HOST_IRQ_STAT: /* R/WC, RO */
+                s->control_regs.irqstatus &= ~val;
+                ahci_check_irq(s);
+                break;
+            case HOST_PORTS_IMPL: /* R/WO, RO */
+                /* FIXME handle R/WO */
+                break;
+            case HOST_VERSION: /* RO */
+                /* FIXME report write? */
+                break;
+            default:
+                DPRINTF(-1, "write to unknown register 0x%x\n", (unsigned)addr);
+        }
+    } else if ((addr >= AHCI_PORT_REGS_START_ADDR) &&
+               (addr < (AHCI_PORT_REGS_START_ADDR +
+                (s->ports * AHCI_PORT_ADDR_OFFSET_LEN)))) {
+        ahci_port_write(s, (addr - AHCI_PORT_REGS_START_ADDR) >> 7,
+                        addr & AHCI_PORT_ADDR_OFFSET_MASK, val);
+    }
+
+}
+
+static const MemoryRegionOps ahci_mem_ops = {
+    .read = ahci_mem_read,
+    .write = ahci_mem_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+};
+
+static uint64_t ahci_idp_read(void *opaque, hwaddr addr,
+                              unsigned size)
+{
+    AHCIState *s = opaque;
+
+    if (addr == s->idp_offset) {
+        /* index register */
+        return s->idp_index;
+    } else if (addr == s->idp_offset + 4) {
+        /* data register - do memory read at location selected by index */
+        return ahci_mem_read(opaque, s->idp_index, size);
+    } else {
+        return 0;
+    }
+}
+
+static void ahci_idp_write(void *opaque, hwaddr addr,
+                           uint64_t val, unsigned size)
+{
+    AHCIState *s = opaque;
+
+    if (addr == s->idp_offset) {
+        /* index register - mask off reserved bits */
+        s->idp_index = (uint32_t)val & ((AHCI_MEM_BAR_SIZE - 1) & ~3);
+    } else if (addr == s->idp_offset + 4) {
+        /* data register - do memory write at location selected by index */
+        ahci_mem_write(opaque, s->idp_index, val, size);
+    }
+}
+
+static const MemoryRegionOps ahci_idp_ops = {
+    .read = ahci_idp_read,
+    .write = ahci_idp_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+};
+
+
+static void ahci_reg_init(AHCIState *s)
+{
+    int i;
+
+    s->control_regs.cap = (s->ports - 1) |
+                          (AHCI_NUM_COMMAND_SLOTS << 8) |
+                          (AHCI_SUPPORTED_SPEED_GEN1 << AHCI_SUPPORTED_SPEED) |
+                          HOST_CAP_NCQ | HOST_CAP_AHCI;
+
+    s->control_regs.impl = (1 << s->ports) - 1;
+
+    s->control_regs.version = AHCI_VERSION_1_0;
+
+    for (i = 0; i < s->ports; i++) {
+        s->dev[i].port_state = STATE_RUN;
+    }
+}
+
+static void check_cmd(AHCIState *s, int port)
+{
+    AHCIPortRegs *pr = &s->dev[port].port_regs;
+    uint8_t slot;
+
+    if ((pr->cmd & PORT_CMD_START) && pr->cmd_issue) {
+        for (slot = 0; (slot < 32) && pr->cmd_issue; slot++) {
+            if ((pr->cmd_issue & (1U << slot)) &&
+                !handle_cmd(s, port, slot)) {
+                pr->cmd_issue &= ~(1U << slot);
+            }
+        }
+    }
+}
+
+static void ahci_check_cmd_bh(void *opaque)
+{
+    AHCIDevice *ad = opaque;
+
+    qemu_bh_delete(ad->check_bh);
+    ad->check_bh = NULL;
+
+    if ((ad->busy_slot != -1) &&
+        !(ad->port.ifs[0].status & (BUSY_STAT|DRQ_STAT))) {
+        /* no longer busy */
+        ad->port_regs.cmd_issue &= ~(1 << ad->busy_slot);
+        ad->busy_slot = -1;
+    }
+
+    check_cmd(ad->hba, ad->port_no);
+}
+
+static void ahci_init_d2h(AHCIDevice *ad)
+{
+    uint8_t init_fis[20];
+    IDEState *ide_state = &ad->port.ifs[0];
+
+    memset(init_fis, 0, sizeof(init_fis));
+
+    init_fis[4] = 1;
+    init_fis[12] = 1;
+
+    if (ide_state->drive_kind == IDE_CD) {
+        init_fis[5] = ide_state->lcyl;
+        init_fis[6] = ide_state->hcyl;
+    }
+
+    ahci_write_fis_d2h(ad, init_fis);
+}
+
+static void ahci_reset_port(AHCIState *s, int port)
+{
+    AHCIDevice *d = &s->dev[port];
+    AHCIPortRegs *pr = &d->port_regs;
+    IDEState *ide_state = &d->port.ifs[0];
+    int i;
+
+    DPRINTF(port, "reset port\n");
+
+    ide_bus_reset(&d->port);
+    ide_state->ncq_queues = AHCI_MAX_CMDS;
+
+    pr->scr_stat = 0;
+    pr->scr_err = 0;
+    pr->scr_act = 0;
+    pr->tfdata = 0x7F;
+    pr->sig = 0xFFFFFFFF;
+    d->busy_slot = -1;
+    d->init_d2h_sent = false;
+
+    ide_state = &s->dev[port].port.ifs[0];
+    if (!ide_state->blk) {
+        return;
+    }
+
+    /* reset ncq queue */
+    for (i = 0; i < AHCI_MAX_CMDS; i++) {
+        NCQTransferState *ncq_tfs = &s->dev[port].ncq_tfs[i];
+        ncq_tfs->halt = false;
+        if (!ncq_tfs->used) {
+            continue;
+        }
+
+        if (ncq_tfs->aiocb) {
+            blk_aio_cancel(ncq_tfs->aiocb);
+            ncq_tfs->aiocb = NULL;
+        }
+
+        /* Maybe we just finished the request thanks to blk_aio_cancel() */
+        if (!ncq_tfs->used) {
+            continue;
+        }
+
+        qemu_sglist_destroy(&ncq_tfs->sglist);
+        ncq_tfs->used = 0;
+    }
+
+    s->dev[port].port_state = STATE_RUN;
+    if (!ide_state->blk) {
+        pr->sig = 0;
+        ide_state->status = SEEK_STAT | WRERR_STAT;
+    } else if (ide_state->drive_kind == IDE_CD) {
+        pr->sig = SATA_SIGNATURE_CDROM;
+        ide_state->lcyl = 0x14;
+        ide_state->hcyl = 0xeb;
+        DPRINTF(port, "set lcyl = %d\n", ide_state->lcyl);
+        ide_state->status = SEEK_STAT | WRERR_STAT | READY_STAT;
+    } else {
+        pr->sig = SATA_SIGNATURE_DISK;
+        ide_state->status = SEEK_STAT | WRERR_STAT;
+    }
+
+    ide_state->error = 1;
+    ahci_init_d2h(d);
+}
+
+static void debug_print_fis(uint8_t *fis, int cmd_len)
+{
+#if DEBUG_AHCI
+    int i;
+
+    fprintf(stderr, "fis:");
+    for (i = 0; i < cmd_len; i++) {
+        if ((i & 0xf) == 0) {
+            fprintf(stderr, "\n%02x:",i);
+        }
+        fprintf(stderr, "%02x ",fis[i]);
+    }
+    fprintf(stderr, "\n");
+#endif
+}
+
+static bool ahci_map_fis_address(AHCIDevice *ad)
+{
+    AHCIPortRegs *pr = &ad->port_regs;
+    map_page(ad->hba->as, &ad->res_fis,
+             ((uint64_t)pr->fis_addr_hi << 32) | pr->fis_addr, 256);
+    return ad->res_fis != NULL;
+}
+
+static void ahci_unmap_fis_address(AHCIDevice *ad)
+{
+    dma_memory_unmap(ad->hba->as, ad->res_fis, 256,
+                     DMA_DIRECTION_FROM_DEVICE, 256);
+    ad->res_fis = NULL;
+}
+
+static bool ahci_map_clb_address(AHCIDevice *ad)
+{
+    AHCIPortRegs *pr = &ad->port_regs;
+    ad->cur_cmd = NULL;
+    map_page(ad->hba->as, &ad->lst,
+             ((uint64_t)pr->lst_addr_hi << 32) | pr->lst_addr, 1024);
+    return ad->lst != NULL;
+}
+
+static void ahci_unmap_clb_address(AHCIDevice *ad)
+{
+    dma_memory_unmap(ad->hba->as, ad->lst, 1024,
+                     DMA_DIRECTION_FROM_DEVICE, 1024);
+    ad->lst = NULL;
+}
+
+static void ahci_write_fis_sdb(AHCIState *s, NCQTransferState *ncq_tfs)
+{
+    AHCIDevice *ad = ncq_tfs->drive;
+    AHCIPortRegs *pr = &ad->port_regs;
+    IDEState *ide_state;
+    SDBFIS *sdb_fis;
+
+    if (!ad->res_fis ||
+        !(pr->cmd & PORT_CMD_FIS_RX)) {
+        return;
+    }
+
+    sdb_fis = (SDBFIS *)&ad->res_fis[RES_FIS_SDBFIS];
+    ide_state = &ad->port.ifs[0];
+
+    sdb_fis->type = SATA_FIS_TYPE_SDB;
+    /* Interrupt pending & Notification bit */
+    sdb_fis->flags = 0x40; /* Interrupt bit, always 1 for NCQ */
+    sdb_fis->status = ide_state->status & 0x77;
+    sdb_fis->error = ide_state->error;
+    /* update SAct field in SDB_FIS */
+    sdb_fis->payload = cpu_to_le32(ad->finished);
+
+    /* Update shadow registers (except BSY 0x80 and DRQ 0x08) */
+    pr->tfdata = (ad->port.ifs[0].error << 8) |
+        (ad->port.ifs[0].status & 0x77) |
+        (pr->tfdata & 0x88);
+    pr->scr_act &= ~ad->finished;
+    ad->finished = 0;
+
+    /* Trigger IRQ if interrupt bit is set (which currently, it always is) */
+    if (sdb_fis->flags & 0x40) {
+        ahci_trigger_irq(s, ad, PORT_IRQ_SDB_FIS);
+    }
+}
+
+static void ahci_write_fis_pio(AHCIDevice *ad, uint16_t len)
+{
+    AHCIPortRegs *pr = &ad->port_regs;
+    uint8_t *pio_fis;
+    IDEState *s = &ad->port.ifs[0];
+
+    if (!ad->res_fis || !(pr->cmd & PORT_CMD_FIS_RX)) {
+        return;
+    }
+
+    pio_fis = &ad->res_fis[RES_FIS_PSFIS];
+
+    pio_fis[0] = SATA_FIS_TYPE_PIO_SETUP;
+    pio_fis[1] = (ad->hba->control_regs.irqstatus ? (1 << 6) : 0);
+    pio_fis[2] = s->status;
+    pio_fis[3] = s->error;
+
+    pio_fis[4] = s->sector;
+    pio_fis[5] = s->lcyl;
+    pio_fis[6] = s->hcyl;
+    pio_fis[7] = s->select;
+    pio_fis[8] = s->hob_sector;
+    pio_fis[9] = s->hob_lcyl;
+    pio_fis[10] = s->hob_hcyl;
+    pio_fis[11] = 0;
+    pio_fis[12] = s->nsector & 0xFF;
+    pio_fis[13] = (s->nsector >> 8) & 0xFF;
+    pio_fis[14] = 0;
+    pio_fis[15] = s->status;
+    pio_fis[16] = len & 255;
+    pio_fis[17] = len >> 8;
+    pio_fis[18] = 0;
+    pio_fis[19] = 0;
+
+    /* Update shadow registers: */
+    pr->tfdata = (ad->port.ifs[0].error << 8) |
+        ad->port.ifs[0].status;
+
+    if (pio_fis[2] & ERR_STAT) {
+        ahci_trigger_irq(ad->hba, ad, PORT_IRQ_TF_ERR);
+    }
+
+    ahci_trigger_irq(ad->hba, ad, PORT_IRQ_PIOS_FIS);
+}
+
+static void ahci_write_fis_d2h(AHCIDevice *ad, uint8_t *cmd_fis)
+{
+    AHCIPortRegs *pr = &ad->port_regs;
+    uint8_t *d2h_fis;
+    int i;
+    IDEState *s = &ad->port.ifs[0];
+
+    if (!ad->res_fis || !(pr->cmd & PORT_CMD_FIS_RX)) {
+        return;
+    }
+
+    d2h_fis = &ad->res_fis[RES_FIS_RFIS];
+
+    d2h_fis[0] = SATA_FIS_TYPE_REGISTER_D2H;
+    d2h_fis[1] = (ad->hba->control_regs.irqstatus ? (1 << 6) : 0);
+    d2h_fis[2] = s->status;
+    d2h_fis[3] = s->error;
+
+    d2h_fis[4] = s->sector;
+    d2h_fis[5] = s->lcyl;
+    d2h_fis[6] = s->hcyl;
+    d2h_fis[7] = s->select;
+    d2h_fis[8] = s->hob_sector;
+    d2h_fis[9] = s->hob_lcyl;
+    d2h_fis[10] = s->hob_hcyl;
+    d2h_fis[11] = 0;
+    d2h_fis[12] = s->nsector & 0xFF;
+    d2h_fis[13] = (s->nsector >> 8) & 0xFF;
+    for (i = 14; i < 20; i++) {
+        d2h_fis[i] = 0;
+    }
+
+    /* Update shadow registers: */
+    pr->tfdata = (ad->port.ifs[0].error << 8) |
+        ad->port.ifs[0].status;
+
+    if (d2h_fis[2] & ERR_STAT) {
+        ahci_trigger_irq(ad->hba, ad, PORT_IRQ_TF_ERR);
+    }
+
+    ahci_trigger_irq(ad->hba, ad, PORT_IRQ_D2H_REG_FIS);
+}
+
+static int prdt_tbl_entry_size(const AHCI_SG *tbl)
+{
+    /* flags_size is zero-based */
+    return (le32_to_cpu(tbl->flags_size) & AHCI_PRDT_SIZE_MASK) + 1;
+}
+
+static int ahci_populate_sglist(AHCIDevice *ad, QEMUSGList *sglist,
+                                AHCICmdHdr *cmd, int64_t limit, int32_t offset)
+{
+    uint16_t opts = le16_to_cpu(cmd->opts);
+    uint16_t prdtl = le16_to_cpu(cmd->prdtl);
+    uint64_t cfis_addr = le64_to_cpu(cmd->tbl_addr);
+    uint64_t prdt_addr = cfis_addr + 0x80;
+    dma_addr_t prdt_len = (prdtl * sizeof(AHCI_SG));
+    dma_addr_t real_prdt_len = prdt_len;
+    uint8_t *prdt;
+    int i;
+    int r = 0;
+    uint64_t sum = 0;
+    int off_idx = -1;
+    int64_t off_pos = -1;
+    int tbl_entry_size;
+    IDEBus *bus = &ad->port;
+    BusState *qbus = BUS(bus);
+
+    /*
+     * Note: AHCI PRDT can describe up to 256GiB. SATA/ATA only support
+     * transactions of up to 32MiB as of ATA8-ACS3 rev 1b, assuming a
+     * 512 byte sector size. We limit the PRDT in this implementation to
+     * a reasonably large 2GiB, which can accommodate the maximum transfer
+     * request for sector sizes up to 32K.
+     */
+
+    if (!prdtl) {
+        DPRINTF(ad->port_no, "no sg list given by guest: 0x%08x\n", opts);
+        return -1;
+    }
+
+    /* map PRDT */
+    if (!(prdt = dma_memory_map(ad->hba->as, prdt_addr, &prdt_len,
+                                DMA_DIRECTION_TO_DEVICE))){
+        DPRINTF(ad->port_no, "map failed\n");
+        return -1;
+    }
+
+    if (prdt_len < real_prdt_len) {
+        DPRINTF(ad->port_no, "mapped less than expected\n");
+        r = -1;
+        goto out;
+    }
+
+    /* Get entries in the PRDT, init a qemu sglist accordingly */
+    if (prdtl > 0) {
+        AHCI_SG *tbl = (AHCI_SG *)prdt;
+        sum = 0;
+        for (i = 0; i < prdtl; i++) {
+            tbl_entry_size = prdt_tbl_entry_size(&tbl[i]);
+            if (offset < (sum + tbl_entry_size)) {
+                off_idx = i;
+                off_pos = offset - sum;
+                break;
+            }
+            sum += tbl_entry_size;
+        }
+        if ((off_idx == -1) || (off_pos < 0) || (off_pos > tbl_entry_size)) {
+            DPRINTF(ad->port_no, "%s: Incorrect offset! "
+                            "off_idx: %d, off_pos: %"PRId64"\n",
+                            __func__, off_idx, off_pos);
+            r = -1;
+            goto out;
+        }
+
+        qemu_sglist_init(sglist, qbus->parent, (prdtl - off_idx),
+                         ad->hba->as);
+        qemu_sglist_add(sglist, le64_to_cpu(tbl[off_idx].addr) + off_pos,
+                        MIN(prdt_tbl_entry_size(&tbl[off_idx]) - off_pos,
+                            limit));
+
+        for (i = off_idx + 1; i < prdtl && sglist->size < limit; i++) {
+            qemu_sglist_add(sglist, le64_to_cpu(tbl[i].addr),
+                            MIN(prdt_tbl_entry_size(&tbl[i]),
+                                limit - sglist->size));
+            if (sglist->size > INT32_MAX) {
+                error_report("AHCI Physical Region Descriptor Table describes "
+                             "more than 2 GiB.\n");
+                qemu_sglist_destroy(sglist);
+                r = -1;
+                goto out;
+            }
+        }
+    }
+
+out:
+    dma_memory_unmap(ad->hba->as, prdt, prdt_len,
+                     DMA_DIRECTION_TO_DEVICE, prdt_len);
+    return r;
+}
+
+static void ncq_err(NCQTransferState *ncq_tfs)
+{
+    IDEState *ide_state = &ncq_tfs->drive->port.ifs[0];
+
+    ide_state->error = ABRT_ERR;
+    ide_state->status = READY_STAT | ERR_STAT;
+    ncq_tfs->drive->port_regs.scr_err |= (1 << ncq_tfs->tag);
+}
+
+static void ncq_finish(NCQTransferState *ncq_tfs)
+{
+    /* If we didn't error out, set our finished bit. Errored commands
+     * do not get a bit set for the SDB FIS ACT register, nor do they
+     * clear the outstanding bit in scr_act (PxSACT). */
+    if (!(ncq_tfs->drive->port_regs.scr_err & (1 << ncq_tfs->tag))) {
+        ncq_tfs->drive->finished |= (1 << ncq_tfs->tag);
+    }
+
+    ahci_write_fis_sdb(ncq_tfs->drive->hba, ncq_tfs);
+
+    DPRINTF(ncq_tfs->drive->port_no, "NCQ transfer tag %d finished\n",
+            ncq_tfs->tag);
+
+    block_acct_done(blk_get_stats(ncq_tfs->drive->port.ifs[0].blk),
+                    &ncq_tfs->acct);
+    qemu_sglist_destroy(&ncq_tfs->sglist);
+    ncq_tfs->used = 0;
+}
+
+static void ncq_cb(void *opaque, int ret)
+{
+    NCQTransferState *ncq_tfs = (NCQTransferState *)opaque;
+    IDEState *ide_state = &ncq_tfs->drive->port.ifs[0];
+
+    if (ret == -ECANCELED) {
+        return;
+    }
+
+    if (ret < 0) {
+        bool is_read = ncq_tfs->cmd == READ_FPDMA_QUEUED;
+        BlockErrorAction action = blk_get_error_action(ide_state->blk,
+                                                       is_read, -ret);
+        if (action == BLOCK_ERROR_ACTION_STOP) {
+            ncq_tfs->halt = true;
+            ide_state->bus->error_status = IDE_RETRY_HBA;
+        } else if (action == BLOCK_ERROR_ACTION_REPORT) {
+            ncq_err(ncq_tfs);
+        }
+        blk_error_action(ide_state->blk, action, is_read, -ret);
+    } else {
+        ide_state->status = READY_STAT | SEEK_STAT;
+    }
+
+    if (!ncq_tfs->halt) {
+        ncq_finish(ncq_tfs);
+    }
+}
+
+static int is_ncq(uint8_t ata_cmd)
+{
+    /* Based on SATA 3.2 section 13.6.3.2 */
+    switch (ata_cmd) {
+    case READ_FPDMA_QUEUED:
+    case WRITE_FPDMA_QUEUED:
+    case NCQ_NON_DATA:
+    case RECEIVE_FPDMA_QUEUED:
+    case SEND_FPDMA_QUEUED:
+        return 1;
+    default:
+        return 0;
+    }
+}
+
+static void execute_ncq_command(NCQTransferState *ncq_tfs)
+{
+    AHCIDevice *ad = ncq_tfs->drive;
+    IDEState *ide_state = &ad->port.ifs[0];
+    int port = ad->port_no;
+
+    g_assert(is_ncq(ncq_tfs->cmd));
+    ncq_tfs->halt = false;
+
+    switch (ncq_tfs->cmd) {
+    case READ_FPDMA_QUEUED:
+        DPRINTF(port, "NCQ reading %d sectors from LBA %"PRId64", tag %d\n",
+                ncq_tfs->sector_count, ncq_tfs->lba, ncq_tfs->tag);
+
+        DPRINTF(port, "tag %d aio read %"PRId64"\n",
+                ncq_tfs->tag, ncq_tfs->lba);
+
+        dma_acct_start(ide_state->blk, &ncq_tfs->acct,
+                       &ncq_tfs->sglist, BLOCK_ACCT_READ);
+        ncq_tfs->aiocb = dma_blk_read(ide_state->blk, &ncq_tfs->sglist,
+                                      ncq_tfs->lba, ncq_cb, ncq_tfs);
+        break;
+    case WRITE_FPDMA_QUEUED:
+        DPRINTF(port, "NCQ writing %d sectors to LBA %"PRId64", tag %d\n",
+                ncq_tfs->sector_count, ncq_tfs->lba, ncq_tfs->tag);
+
+        DPRINTF(port, "tag %d aio write %"PRId64"\n",
+                ncq_tfs->tag, ncq_tfs->lba);
+
+        dma_acct_start(ide_state->blk, &ncq_tfs->acct,
+                       &ncq_tfs->sglist, BLOCK_ACCT_WRITE);
+        ncq_tfs->aiocb = dma_blk_write(ide_state->blk, &ncq_tfs->sglist,
+                                       ncq_tfs->lba, ncq_cb, ncq_tfs);
+        break;
+    default:
+        DPRINTF(port, "error: unsupported NCQ command (0x%02x) received\n",
+                ncq_tfs->cmd);
+        qemu_sglist_destroy(&ncq_tfs->sglist);
+        ncq_err(ncq_tfs);
+    }
+}
+
+
+static void process_ncq_command(AHCIState *s, int port, uint8_t *cmd_fis,
+                                uint8_t slot)
+{
+    AHCIDevice *ad = &s->dev[port];
+    IDEState *ide_state = &ad->port.ifs[0];
+    NCQFrame *ncq_fis = (NCQFrame*)cmd_fis;
+    uint8_t tag = ncq_fis->tag >> 3;
+    NCQTransferState *ncq_tfs = &ad->ncq_tfs[tag];
+    size_t size;
+
+    g_assert(is_ncq(ncq_fis->command));
+    if (ncq_tfs->used) {
+        /* error - already in use */
+        fprintf(stderr, "%s: tag %d already used\n", __FUNCTION__, tag);
+        return;
+    }
+
+    ncq_tfs->used = 1;
+    ncq_tfs->drive = ad;
+    ncq_tfs->slot = slot;
+    ncq_tfs->cmdh = &((AHCICmdHdr *)ad->lst)[slot];
+    ncq_tfs->cmd = ncq_fis->command;
+    ncq_tfs->lba = ((uint64_t)ncq_fis->lba5 << 40) |
+                   ((uint64_t)ncq_fis->lba4 << 32) |
+                   ((uint64_t)ncq_fis->lba3 << 24) |
+                   ((uint64_t)ncq_fis->lba2 << 16) |
+                   ((uint64_t)ncq_fis->lba1 << 8) |
+                   (uint64_t)ncq_fis->lba0;
+    ncq_tfs->tag = tag;
+
+    /* Sanity-check the NCQ packet */
+    if (tag != slot) {
+        DPRINTF(port, "Warn: NCQ slot (%d) did not match the given tag (%d)\n",
+                slot, tag);
+    }
+
+    if (ncq_fis->aux0 || ncq_fis->aux1 || ncq_fis->aux2 || ncq_fis->aux3) {
+        DPRINTF(port, "Warn: Attempt to use NCQ auxiliary fields.\n");
+    }
+    if (ncq_fis->prio || ncq_fis->icc) {
+        DPRINTF(port, "Warn: Unsupported attempt to use PRIO/ICC fields\n");
+    }
+    if (ncq_fis->fua & NCQ_FIS_FUA_MASK) {
+        DPRINTF(port, "Warn: Unsupported attempt to use Force Unit Access\n");
+    }
+    if (ncq_fis->tag & NCQ_FIS_RARC_MASK) {
+        DPRINTF(port, "Warn: Unsupported attempt to use Rebuild Assist\n");
+    }
+
+    ncq_tfs->sector_count = ((ncq_fis->sector_count_high << 8) |
+                             ncq_fis->sector_count_low);
+    if (!ncq_tfs->sector_count) {
+        ncq_tfs->sector_count = 0x10000;
+    }
+    size = ncq_tfs->sector_count * 512;
+    ahci_populate_sglist(ad, &ncq_tfs->sglist, ncq_tfs->cmdh, size, 0);
+
+    if (ncq_tfs->sglist.size < size) {
+        error_report("ahci: PRDT length for NCQ command (0x%zx) "
+                     "is smaller than the requested size (0x%zx)",
+                     ncq_tfs->sglist.size, size);
+        qemu_sglist_destroy(&ncq_tfs->sglist);
+        ncq_err(ncq_tfs);
+        ahci_trigger_irq(ad->hba, ad, PORT_IRQ_OVERFLOW);
+        return;
+    } else if (ncq_tfs->sglist.size != size) {
+        DPRINTF(port, "Warn: PRDTL (0x%zx)"
+                " does not match requested size (0x%zx)",
+                ncq_tfs->sglist.size, size);
+    }
+
+    DPRINTF(port, "NCQ transfer LBA from %"PRId64" to %"PRId64", "
+            "drive max %"PRId64"\n",
+            ncq_tfs->lba, ncq_tfs->lba + ncq_tfs->sector_count - 1,
+            ide_state->nb_sectors - 1);
+
+    execute_ncq_command(ncq_tfs);
+}
+
+static AHCICmdHdr *get_cmd_header(AHCIState *s, uint8_t port, uint8_t slot)
+{
+    if (port >= s->ports || slot >= AHCI_MAX_CMDS) {
+        return NULL;
+    }
+
+    return s->dev[port].lst ? &((AHCICmdHdr *)s->dev[port].lst)[slot] : NULL;
+}
+
+static void handle_reg_h2d_fis(AHCIState *s, int port,
+                               uint8_t slot, uint8_t *cmd_fis)
+{
+    IDEState *ide_state = &s->dev[port].port.ifs[0];
+    AHCICmdHdr *cmd = get_cmd_header(s, port, slot);
+    uint16_t opts = le16_to_cpu(cmd->opts);
+
+    if (cmd_fis[1] & 0x0F) {
+        DPRINTF(port, "Port Multiplier not supported."
+                " cmd_fis[0]=%02x cmd_fis[1]=%02x cmd_fis[2]=%02x\n",
+                cmd_fis[0], cmd_fis[1], cmd_fis[2]);
+        return;
+    }
+
+    if (cmd_fis[1] & 0x70) {
+        DPRINTF(port, "Reserved flags set in H2D Register FIS."
+                " cmd_fis[0]=%02x cmd_fis[1]=%02x cmd_fis[2]=%02x\n",
+                cmd_fis[0], cmd_fis[1], cmd_fis[2]);
+        return;
+    }
+
+    if (!(cmd_fis[1] & SATA_FIS_REG_H2D_UPDATE_COMMAND_REGISTER)) {
+        switch (s->dev[port].port_state) {
+        case STATE_RUN:
+            if (cmd_fis[15] & ATA_SRST) {
+                s->dev[port].port_state = STATE_RESET;
+            }
+            break;
+        case STATE_RESET:
+            if (!(cmd_fis[15] & ATA_SRST)) {
+                ahci_reset_port(s, port);
+            }
+            break;
+        }
+        return;
+    }
+
+    /* Check for NCQ command */
+    if (is_ncq(cmd_fis[2])) {
+        process_ncq_command(s, port, cmd_fis, slot);
+        return;
+    }
+
+    /* Decompose the FIS:
+     * AHCI does not interpret FIS packets, it only forwards them.
+     * SATA 1.0 describes how to decode LBA28 and CHS FIS packets.
+     * Later specifications, e.g, SATA 3.2, describe LBA48 FIS packets.
+     *
+     * ATA4 describes sector number for LBA28/CHS commands.
+     * ATA6 describes sector number for LBA48 commands.
+     * ATA8 deprecates CHS fully, describing only LBA28/48.
+     *
+     * We dutifully convert the FIS into IDE registers, and allow the
+     * core layer to interpret them as needed. */
+    ide_state->feature = cmd_fis[3];
+    ide_state->sector = cmd_fis[4];      /* LBA 7:0 */
+    ide_state->lcyl = cmd_fis[5];        /* LBA 15:8  */
+    ide_state->hcyl = cmd_fis[6];        /* LBA 23:16 */
+    ide_state->select = cmd_fis[7];      /* LBA 27:24 (LBA28) */
+    ide_state->hob_sector = cmd_fis[8];  /* LBA 31:24 */
+    ide_state->hob_lcyl = cmd_fis[9];    /* LBA 39:32 */
+    ide_state->hob_hcyl = cmd_fis[10];   /* LBA 47:40 */
+    ide_state->hob_feature = cmd_fis[11];
+    ide_state->nsector = (int64_t)((cmd_fis[13] << 8) | cmd_fis[12]);
+    /* 14, 16, 17, 18, 19: Reserved (SATA 1.0) */
+    /* 15: Only valid when UPDATE_COMMAND not set. */
+
+    /* Copy the ACMD field (ATAPI packet, if any) from the AHCI command
+     * table to ide_state->io_buffer */
+    if (opts & AHCI_CMD_ATAPI) {
+        memcpy(ide_state->io_buffer, &cmd_fis[AHCI_COMMAND_TABLE_ACMD], 0x10);
+        debug_print_fis(ide_state->io_buffer, 0x10);
+        s->dev[port].done_atapi_packet = false;
+        /* XXX send PIO setup FIS */
+    }
+
+    ide_state->error = 0;
+
+    /* Reset transferred byte counter */
+    cmd->status = 0;
+
+    /* We're ready to process the command in FIS byte 2. */
+    ide_exec_cmd(&s->dev[port].port, cmd_fis[2]);
+}
+
+static int handle_cmd(AHCIState *s, int port, uint8_t slot)
+{
+    IDEState *ide_state;
+    uint64_t tbl_addr;
+    AHCICmdHdr *cmd;
+    uint8_t *cmd_fis;
+    dma_addr_t cmd_len;
+
+    if (s->dev[port].port.ifs[0].status & (BUSY_STAT|DRQ_STAT)) {
+        /* Engine currently busy, try again later */
+        DPRINTF(port, "engine busy\n");
+        return -1;
+    }
+
+    if (!s->dev[port].lst) {
+        DPRINTF(port, "error: lst not given but cmd handled");
+        return -1;
+    }
+    cmd = get_cmd_header(s, port, slot);
+    /* remember current slot handle for later */
+    s->dev[port].cur_cmd = cmd;
+
+    /* The device we are working for */
+    ide_state = &s->dev[port].port.ifs[0];
+    if (!ide_state->blk) {
+        DPRINTF(port, "error: guest accessed unused port");
+        return -1;
+    }
+
+    tbl_addr = le64_to_cpu(cmd->tbl_addr);
+    cmd_len = 0x80;
+    cmd_fis = dma_memory_map(s->as, tbl_addr, &cmd_len,
+                             DMA_DIRECTION_FROM_DEVICE);
+    if (!cmd_fis) {
+        DPRINTF(port, "error: guest passed us an invalid cmd fis\n");
+        return -1;
+    } else if (cmd_len != 0x80) {
+        ahci_trigger_irq(s, &s->dev[port], PORT_IRQ_HBUS_ERR);
+        DPRINTF(port, "error: dma_memory_map failed: "
+                "(len(%02"PRIx64") != 0x80)\n",
+                cmd_len);
+        goto out;
+    }
+    debug_print_fis(cmd_fis, 0x80);
+
+    switch (cmd_fis[0]) {
+        case SATA_FIS_TYPE_REGISTER_H2D:
+            handle_reg_h2d_fis(s, port, slot, cmd_fis);
+            break;
+        default:
+            DPRINTF(port, "unknown command cmd_fis[0]=%02x cmd_fis[1]=%02x "
+                          "cmd_fis[2]=%02x\n", cmd_fis[0], cmd_fis[1],
+                          cmd_fis[2]);
+            break;
+    }
+
+out:
+    dma_memory_unmap(s->as, cmd_fis, cmd_len, DMA_DIRECTION_FROM_DEVICE,
+                     cmd_len);
+
+    if (s->dev[port].port.ifs[0].status & (BUSY_STAT|DRQ_STAT)) {
+        /* async command, complete later */
+        s->dev[port].busy_slot = slot;
+        return -1;
+    }
+
+    /* done handling the command */
+    return 0;
+}
+
+/* DMA dev <-> ram */
+static void ahci_start_transfer(IDEDMA *dma)
+{
+    AHCIDevice *ad = DO_UPCAST(AHCIDevice, dma, dma);
+    IDEState *s = &ad->port.ifs[0];
+    uint32_t size = (uint32_t)(s->data_end - s->data_ptr);
+    /* write == ram -> device */
+    uint16_t opts = le16_to_cpu(ad->cur_cmd->opts);
+    int is_write = opts & AHCI_CMD_WRITE;
+    int is_atapi = opts & AHCI_CMD_ATAPI;
+    int has_sglist = 0;
+
+    if (is_atapi && !ad->done_atapi_packet) {
+        /* already prepopulated iobuffer */
+        ad->done_atapi_packet = true;
+        size = 0;
+        goto out;
+    }
+
+    if (ahci_dma_prepare_buf(dma, size)) {
+        has_sglist = 1;
+    }
+
+    DPRINTF(ad->port_no, "%sing %d bytes on %s w/%s sglist\n",
+            is_write ? "writ" : "read", size, is_atapi ? "atapi" : "ata",
+            has_sglist ? "" : "o");
+
+    if (has_sglist && size) {
+        if (is_write) {
+            dma_buf_write(s->data_ptr, size, &s->sg);
+        } else {
+            dma_buf_read(s->data_ptr, size, &s->sg);
+        }
+    }
+
+out:
+    /* declare that we processed everything */
+    s->data_ptr = s->data_end;
+
+    /* Update number of transferred bytes, destroy sglist */
+    ahci_commit_buf(dma, size);
+
+    s->end_transfer_func(s);
+
+    if (!(s->status & DRQ_STAT)) {
+        /* done with PIO send/receive */
+        ahci_write_fis_pio(ad, le32_to_cpu(ad->cur_cmd->status));
+    }
+}
+
+static void ahci_start_dma(IDEDMA *dma, IDEState *s,
+                           BlockCompletionFunc *dma_cb)
+{
+    AHCIDevice *ad = DO_UPCAST(AHCIDevice, dma, dma);
+    DPRINTF(ad->port_no, "\n");
+    s->io_buffer_offset = 0;
+    dma_cb(s, 0);
+}
+
+static void ahci_restart_dma(IDEDMA *dma)
+{
+    /* Nothing to do, ahci_start_dma already resets s->io_buffer_offset.  */
+}
+
+/**
+ * IDE/PIO restarts are handled by the core layer, but NCQ commands
+ * need an extra kick from the AHCI HBA.
+ */
+static void ahci_restart(IDEDMA *dma)
+{
+    AHCIDevice *ad = DO_UPCAST(AHCIDevice, dma, dma);
+    int i;
+
+    for (i = 0; i < AHCI_MAX_CMDS; i++) {
+        NCQTransferState *ncq_tfs = &ad->ncq_tfs[i];
+        if (ncq_tfs->halt) {
+            execute_ncq_command(ncq_tfs);
+        }
+    }
+}
+
+/**
+ * Called in DMA R/W chains to read the PRDT, utilizing ahci_populate_sglist.
+ * Not currently invoked by PIO R/W chains,
+ * which invoke ahci_populate_sglist via ahci_start_transfer.
+ */
+static int32_t ahci_dma_prepare_buf(IDEDMA *dma, int32_t limit)
+{
+    AHCIDevice *ad = DO_UPCAST(AHCIDevice, dma, dma);
+    IDEState *s = &ad->port.ifs[0];
+
+    if (ahci_populate_sglist(ad, &s->sg, ad->cur_cmd,
+                             limit, s->io_buffer_offset) == -1) {
+        DPRINTF(ad->port_no, "ahci_dma_prepare_buf failed.\n");
+        return -1;
+    }
+    s->io_buffer_size = s->sg.size;
+
+    DPRINTF(ad->port_no, "len=%#x\n", s->io_buffer_size);
+    return s->io_buffer_size;
+}
+
+/**
+ * Destroys the scatter-gather list,
+ * and updates the command header with a bytes-read value.
+ * called explicitly via ahci_dma_rw_buf (ATAPI DMA),
+ * and ahci_start_transfer (PIO R/W),
+ * and called via callback from ide_dma_cb for DMA R/W paths.
+ */
+static void ahci_commit_buf(IDEDMA *dma, uint32_t tx_bytes)
+{
+    AHCIDevice *ad = DO_UPCAST(AHCIDevice, dma, dma);
+    IDEState *s = &ad->port.ifs[0];
+
+    tx_bytes += le32_to_cpu(ad->cur_cmd->status);
+    ad->cur_cmd->status = cpu_to_le32(tx_bytes);
+
+    qemu_sglist_destroy(&s->sg);
+}
+
+static int ahci_dma_rw_buf(IDEDMA *dma, int is_write)
+{
+    AHCIDevice *ad = DO_UPCAST(AHCIDevice, dma, dma);
+    IDEState *s = &ad->port.ifs[0];
+    uint8_t *p = s->io_buffer + s->io_buffer_index;
+    int l = s->io_buffer_size - s->io_buffer_index;
+
+    if (ahci_populate_sglist(ad, &s->sg, ad->cur_cmd, l, s->io_buffer_offset)) {
+        return 0;
+    }
+
+    if (is_write) {
+        dma_buf_read(p, l, &s->sg);
+    } else {
+        dma_buf_write(p, l, &s->sg);
+    }
+
+    /* free sglist, update byte count */
+    ahci_commit_buf(dma, l);
+
+    s->io_buffer_index += l;
+    s->io_buffer_offset += l;
+
+    DPRINTF(ad->port_no, "len=%#x\n", l);
+
+    return 1;
+}
+
+static void ahci_cmd_done(IDEDMA *dma)
+{
+    AHCIDevice *ad = DO_UPCAST(AHCIDevice, dma, dma);
+
+    DPRINTF(ad->port_no, "cmd done\n");
+
+    /* update d2h status */
+    ahci_write_fis_d2h(ad, NULL);
+
+    if (!ad->check_bh) {
+        /* maybe we still have something to process, check later */
+        ad->check_bh = qemu_bh_new(ahci_check_cmd_bh, ad);
+        qemu_bh_schedule(ad->check_bh);
+    }
+}
+
+static void ahci_irq_set(void *opaque, int n, int level)
+{
+}
+
+static const IDEDMAOps ahci_dma_ops = {
+    .start_dma = ahci_start_dma,
+    .restart = ahci_restart,
+    .restart_dma = ahci_restart_dma,
+    .start_transfer = ahci_start_transfer,
+    .prepare_buf = ahci_dma_prepare_buf,
+    .commit_buf = ahci_commit_buf,
+    .rw_buf = ahci_dma_rw_buf,
+    .cmd_done = ahci_cmd_done,
+};
+
+void ahci_init(AHCIState *s, DeviceState *qdev, AddressSpace *as, int ports)
+{
+    qemu_irq *irqs;
+    int i;
+
+    s->as = as;
+    s->ports = ports;
+    s->dev = g_new0(AHCIDevice, ports);
+    ahci_reg_init(s);
+    /* XXX BAR size should be 1k, but that breaks, so bump it to 4k for now */
+    memory_region_init_io(&s->mem, OBJECT(qdev), &ahci_mem_ops, s,
+                          "ahci", AHCI_MEM_BAR_SIZE);
+    memory_region_init_io(&s->idp, OBJECT(qdev), &ahci_idp_ops, s,
+                          "ahci-idp", 32);
+
+    irqs = qemu_allocate_irqs(ahci_irq_set, s, s->ports);
+
+    for (i = 0; i < s->ports; i++) {
+        AHCIDevice *ad = &s->dev[i];
+
+        ide_bus_new(&ad->port, sizeof(ad->port), qdev, i, 1);
+        ide_init2(&ad->port, irqs[i]);
+
+        ad->hba = s;
+        ad->port_no = i;
+        ad->port.dma = &ad->dma;
+        ad->port.dma->ops = &ahci_dma_ops;
+        ide_register_restart_cb(&ad->port);
+    }
+}
+
+void ahci_uninit(AHCIState *s)
+{
+    g_free(s->dev);
+}
+
+void ahci_reset(AHCIState *s)
+{
+    AHCIPortRegs *pr;
+    int i;
+
+    s->control_regs.irqstatus = 0;
+    /* AHCI Enable (AE)
+     * The implementation of this bit is dependent upon the value of the
+     * CAP.SAM bit. If CAP.SAM is '0', then GHC.AE shall be read-write and
+     * shall have a reset value of '0'. If CAP.SAM is '1', then AE shall be
+     * read-only and shall have a reset value of '1'.
+     *
+     * We set HOST_CAP_AHCI so we must enable AHCI at reset.
+     */
+    s->control_regs.ghc = HOST_CTL_AHCI_EN;
+
+    for (i = 0; i < s->ports; i++) {
+        pr = &s->dev[i].port_regs;
+        pr->irq_stat = 0;
+        pr->irq_mask = 0;
+        pr->scr_ctl = 0;
+        pr->cmd = PORT_CMD_SPIN_UP | PORT_CMD_POWER_ON;
+        ahci_reset_port(s, i);
+    }
+}
+
+static const VMStateDescription vmstate_ncq_tfs = {
+    .name = "ncq state",
+    .version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(sector_count, NCQTransferState),
+        VMSTATE_UINT64(lba, NCQTransferState),
+        VMSTATE_UINT8(tag, NCQTransferState),
+        VMSTATE_UINT8(cmd, NCQTransferState),
+        VMSTATE_UINT8(slot, NCQTransferState),
+        VMSTATE_BOOL(used, NCQTransferState),
+        VMSTATE_BOOL(halt, NCQTransferState),
+        VMSTATE_END_OF_LIST()
+    },
+};
+
+static const VMStateDescription vmstate_ahci_device = {
+    .name = "ahci port",
+    .version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_IDE_BUS(port, AHCIDevice),
+        VMSTATE_IDE_DRIVE(port.ifs[0], AHCIDevice),
+        VMSTATE_UINT32(port_state, AHCIDevice),
+        VMSTATE_UINT32(finished, AHCIDevice),
+        VMSTATE_UINT32(port_regs.lst_addr, AHCIDevice),
+        VMSTATE_UINT32(port_regs.lst_addr_hi, AHCIDevice),
+        VMSTATE_UINT32(port_regs.fis_addr, AHCIDevice),
+        VMSTATE_UINT32(port_regs.fis_addr_hi, AHCIDevice),
+        VMSTATE_UINT32(port_regs.irq_stat, AHCIDevice),
+        VMSTATE_UINT32(port_regs.irq_mask, AHCIDevice),
+        VMSTATE_UINT32(port_regs.cmd, AHCIDevice),
+        VMSTATE_UINT32(port_regs.tfdata, AHCIDevice),
+        VMSTATE_UINT32(port_regs.sig, AHCIDevice),
+        VMSTATE_UINT32(port_regs.scr_stat, AHCIDevice),
+        VMSTATE_UINT32(port_regs.scr_ctl, AHCIDevice),
+        VMSTATE_UINT32(port_regs.scr_err, AHCIDevice),
+        VMSTATE_UINT32(port_regs.scr_act, AHCIDevice),
+        VMSTATE_UINT32(port_regs.cmd_issue, AHCIDevice),
+        VMSTATE_BOOL(done_atapi_packet, AHCIDevice),
+        VMSTATE_INT32(busy_slot, AHCIDevice),
+        VMSTATE_BOOL(init_d2h_sent, AHCIDevice),
+        VMSTATE_STRUCT_ARRAY(ncq_tfs, AHCIDevice, AHCI_MAX_CMDS,
+                             1, vmstate_ncq_tfs, NCQTransferState),
+        VMSTATE_END_OF_LIST()
+    },
+};
+
+static int ahci_state_post_load(void *opaque, int version_id)
+{
+    int i, j;
+    struct AHCIDevice *ad;
+    NCQTransferState *ncq_tfs;
+    AHCIState *s = opaque;
+
+    for (i = 0; i < s->ports; i++) {
+        ad = &s->dev[i];
+
+        /* Only remap the CLB address if appropriate, disallowing a state
+         * transition from 'on' to 'off' it should be consistent here. */
+        if (ahci_cond_start_engines(ad, false) != 0) {
+            return -1;
+        }
+
+        for (j = 0; j < AHCI_MAX_CMDS; j++) {
+            ncq_tfs = &ad->ncq_tfs[j];
+            ncq_tfs->drive = ad;
+
+            if (ncq_tfs->used != ncq_tfs->halt) {
+                return -1;
+            }
+            if (!ncq_tfs->halt) {
+                continue;
+            }
+            if (!is_ncq(ncq_tfs->cmd)) {
+                return -1;
+            }
+            if (ncq_tfs->slot != ncq_tfs->tag) {
+                return -1;
+            }
+            /* If ncq_tfs->halt is justly set, the engine should be engaged,
+             * and the command list buffer should be mapped. */
+            ncq_tfs->cmdh = get_cmd_header(s, i, ncq_tfs->slot);
+            if (!ncq_tfs->cmdh) {
+                return -1;
+            }
+            ahci_populate_sglist(ncq_tfs->drive, &ncq_tfs->sglist,
+                                 ncq_tfs->cmdh, ncq_tfs->sector_count * 512,
+                                 0);
+            if (ncq_tfs->sector_count != ncq_tfs->sglist.size >> 9) {
+                return -1;
+            }
+        }
+
+
+        /*
+         * If an error is present, ad->busy_slot will be valid and not -1.
+         * In this case, an operation is waiting to resume and will re-check
+         * for additional AHCI commands to execute upon completion.
+         *
+         * In the case where no error was present, busy_slot will be -1,
+         * and we should check to see if there are additional commands waiting.
+         */
+        if (ad->busy_slot == -1) {
+            check_cmd(s, i);
+        } else {
+            /* We are in the middle of a command, and may need to access
+             * the command header in guest memory again. */
+            if (ad->busy_slot < 0 || ad->busy_slot >= AHCI_MAX_CMDS) {
+                return -1;
+            }
+            ad->cur_cmd = get_cmd_header(s, i, ad->busy_slot);
+        }
+    }
+
+    return 0;
+}
+
+const VMStateDescription vmstate_ahci = {
+    .name = "ahci",
+    .version_id = 1,
+    .post_load = ahci_state_post_load,
+    .fields = (VMStateField[]) {
+        VMSTATE_STRUCT_VARRAY_POINTER_INT32(dev, AHCIState, ports,
+                                     vmstate_ahci_device, AHCIDevice),
+        VMSTATE_UINT32(control_regs.cap, AHCIState),
+        VMSTATE_UINT32(control_regs.ghc, AHCIState),
+        VMSTATE_UINT32(control_regs.irqstatus, AHCIState),
+        VMSTATE_UINT32(control_regs.impl, AHCIState),
+        VMSTATE_UINT32(control_regs.version, AHCIState),
+        VMSTATE_UINT32(idp_index, AHCIState),
+        VMSTATE_INT32_EQUAL(ports, AHCIState),
+        VMSTATE_END_OF_LIST()
+    },
+};
+
+#define TYPE_SYSBUS_AHCI "sysbus-ahci"
+#define SYSBUS_AHCI(obj) OBJECT_CHECK(SysbusAHCIState, (obj), TYPE_SYSBUS_AHCI)
+
+typedef struct SysbusAHCIState {
+    /*< private >*/
+    SysBusDevice parent_obj;
+    /*< public >*/
+
+    AHCIState ahci;
+    uint32_t num_ports;
+} SysbusAHCIState;
+
+static const VMStateDescription vmstate_sysbus_ahci = {
+    .name = "sysbus-ahci",
+    .fields = (VMStateField[]) {
+        VMSTATE_AHCI(ahci, SysbusAHCIState),
+        VMSTATE_END_OF_LIST()
+    },
+};
+
+static void sysbus_ahci_reset(DeviceState *dev)
+{
+    SysbusAHCIState *s = SYSBUS_AHCI(dev);
+
+    ahci_reset(&s->ahci);
+}
+
+static void sysbus_ahci_realize(DeviceState *dev, Error **errp)
+{
+    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
+    SysbusAHCIState *s = SYSBUS_AHCI(dev);
+
+    ahci_init(&s->ahci, dev, &address_space_memory, s->num_ports);
+
+    sysbus_init_mmio(sbd, &s->ahci.mem);
+    sysbus_init_irq(sbd, &s->ahci.irq);
+}
+
+static Property sysbus_ahci_properties[] = {
+    DEFINE_PROP_UINT32("num-ports", SysbusAHCIState, num_ports, 1),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void sysbus_ahci_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->realize = sysbus_ahci_realize;
+    dc->vmsd = &vmstate_sysbus_ahci;
+    dc->props = sysbus_ahci_properties;
+    dc->reset = sysbus_ahci_reset;
+    set_bit(DEVICE_CATEGORY_STORAGE, dc->categories);
+}
+
+static const TypeInfo sysbus_ahci_info = {
+    .name          = TYPE_SYSBUS_AHCI,
+    .parent        = TYPE_SYS_BUS_DEVICE,
+    .instance_size = sizeof(SysbusAHCIState),
+    .class_init    = sysbus_ahci_class_init,
+};
+
+static void sysbus_ahci_register_types(void)
+{
+    type_register_static(&sysbus_ahci_info);
+}
+
+type_init(sysbus_ahci_register_types)
+
+void ahci_ide_create_devs(PCIDevice *dev, DriveInfo **hd)
+{
+    AHCIPCIState *d = ICH_AHCI(dev);
+    AHCIState *ahci = &d->ahci;
+    int i;
+
+    for (i = 0; i < ahci->ports; i++) {
+        if (hd[i] == NULL) {
+            continue;
+        }
+        ide_create_drive(&ahci->dev[i].port, 0, hd[i]);
+    }
+
+}