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-rw-r--r--kernel/arch/x86/xen/Kconfig4
-rw-r--r--kernel/arch/x86/xen/Makefile4
-rw-r--r--kernel/arch/x86/xen/enlighten.c40
-rw-r--r--kernel/arch/x86/xen/xen-ops.h6
4 files changed, 46 insertions, 8 deletions
diff --git a/kernel/arch/x86/xen/Kconfig b/kernel/arch/x86/xen/Kconfig
index e88fda867..484145368 100644
--- a/kernel/arch/x86/xen/Kconfig
+++ b/kernel/arch/x86/xen/Kconfig
@@ -8,7 +8,7 @@ config XEN
select PARAVIRT_CLOCK
select XEN_HAVE_PVMMU
depends on X86_64 || (X86_32 && X86_PAE)
- depends on X86_TSC
+ depends on X86_LOCAL_APIC && X86_TSC
help
This is the Linux Xen port. Enabling this will allow the
kernel to boot in a paravirtualized environment under the
@@ -17,7 +17,7 @@ config XEN
config XEN_DOM0
def_bool y
depends on XEN && PCI_XEN && SWIOTLB_XEN
- depends on X86_LOCAL_APIC && X86_IO_APIC && ACPI && PCI
+ depends on X86_IO_APIC && ACPI && PCI
config XEN_PVHVM
def_bool y
diff --git a/kernel/arch/x86/xen/Makefile b/kernel/arch/x86/xen/Makefile
index 7322755f3..4b6e29ac0 100644
--- a/kernel/arch/x86/xen/Makefile
+++ b/kernel/arch/x86/xen/Makefile
@@ -13,13 +13,13 @@ CFLAGS_mmu.o := $(nostackp)
obj-y := enlighten.o setup.o multicalls.o mmu.o irq.o \
time.o xen-asm.o xen-asm_$(BITS).o \
grant-table.o suspend.o platform-pci-unplug.o \
- p2m.o
+ p2m.o apic.o
obj-$(CONFIG_EVENT_TRACING) += trace.o
obj-$(CONFIG_SMP) += smp.o
obj-$(CONFIG_PARAVIRT_SPINLOCKS)+= spinlock.o
obj-$(CONFIG_XEN_DEBUG_FS) += debugfs.o
-obj-$(CONFIG_XEN_DOM0) += apic.o vga.o
+obj-$(CONFIG_XEN_DOM0) += vga.o
obj-$(CONFIG_SWIOTLB_XEN) += pci-swiotlb-xen.o
obj-$(CONFIG_XEN_EFI) += efi.o
diff --git a/kernel/arch/x86/xen/enlighten.c b/kernel/arch/x86/xen/enlighten.c
index 46957ead3..a671e8372 100644
--- a/kernel/arch/x86/xen/enlighten.c
+++ b/kernel/arch/x86/xen/enlighten.c
@@ -483,6 +483,7 @@ static void set_aliased_prot(void *v, pgprot_t prot)
pte_t pte;
unsigned long pfn;
struct page *page;
+ unsigned char dummy;
ptep = lookup_address((unsigned long)v, &level);
BUG_ON(ptep == NULL);
@@ -492,6 +493,32 @@ static void set_aliased_prot(void *v, pgprot_t prot)
pte = pfn_pte(pfn, prot);
+ /*
+ * Careful: update_va_mapping() will fail if the virtual address
+ * we're poking isn't populated in the page tables. We don't
+ * need to worry about the direct map (that's always in the page
+ * tables), but we need to be careful about vmap space. In
+ * particular, the top level page table can lazily propagate
+ * entries between processes, so if we've switched mms since we
+ * vmapped the target in the first place, we might not have the
+ * top-level page table entry populated.
+ *
+ * We disable preemption because we want the same mm active when
+ * we probe the target and when we issue the hypercall. We'll
+ * have the same nominal mm, but if we're a kernel thread, lazy
+ * mm dropping could change our pgd.
+ *
+ * Out of an abundance of caution, this uses __get_user() to fault
+ * in the target address just in case there's some obscure case
+ * in which the target address isn't readable.
+ */
+
+ preempt_disable();
+
+ pagefault_disable(); /* Avoid warnings due to being atomic. */
+ __get_user(dummy, (unsigned char __user __force *)v);
+ pagefault_enable();
+
if (HYPERVISOR_update_va_mapping((unsigned long)v, pte, 0))
BUG();
@@ -503,6 +530,8 @@ static void set_aliased_prot(void *v, pgprot_t prot)
BUG();
} else
kmap_flush_unused();
+
+ preempt_enable();
}
static void xen_alloc_ldt(struct desc_struct *ldt, unsigned entries)
@@ -510,6 +539,17 @@ static void xen_alloc_ldt(struct desc_struct *ldt, unsigned entries)
const unsigned entries_per_page = PAGE_SIZE / LDT_ENTRY_SIZE;
int i;
+ /*
+ * We need to mark the all aliases of the LDT pages RO. We
+ * don't need to call vm_flush_aliases(), though, since that's
+ * only responsible for flushing aliases out the TLBs, not the
+ * page tables, and Xen will flush the TLB for us if needed.
+ *
+ * To avoid confusing future readers: none of this is necessary
+ * to load the LDT. The hypervisor only checks this when the
+ * LDT is faulted in due to subsequent descriptor access.
+ */
+
for(i = 0; i < entries; i += entries_per_page)
set_aliased_prot(ldt + i, PAGE_KERNEL_RO);
}
diff --git a/kernel/arch/x86/xen/xen-ops.h b/kernel/arch/x86/xen/xen-ops.h
index 9e195c683..bef30cbb5 100644
--- a/kernel/arch/x86/xen/xen-ops.h
+++ b/kernel/arch/x86/xen/xen-ops.h
@@ -101,17 +101,15 @@ struct dom0_vga_console_info;
#ifdef CONFIG_XEN_DOM0
void __init xen_init_vga(const struct dom0_vga_console_info *, size_t size);
-void __init xen_init_apic(void);
#else
static inline void __init xen_init_vga(const struct dom0_vga_console_info *info,
size_t size)
{
}
-static inline void __init xen_init_apic(void)
-{
-}
#endif
+void __init xen_init_apic(void);
+
#ifdef CONFIG_XEN_EFI
extern void xen_efi_init(void);
#else