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authorAvi Kivity <avi@qumranet.com>2008-07-13 11:33:54 +0300
committerAvi Kivity <avi@qumranet.com>2008-07-20 12:42:40 +0300
commit722c05f2192070bac0208b2c16ce13929b32d92f (patch)
tree918037277cd65ec4abc1a9b5b15dcf0b8bb8fe25 /arch
parent2a7c5b8b550b1fb1db9eb490420132e637f5dcb4 (diff)
KVM: MMU: Fix potential race setting upper shadow ptes on nonpae hosts
The direct mapped shadow code (used for real mode and two dimensional paging) sets upper-level ptes using direct assignment rather than calling set_shadow_pte(). A nonpae host will split this into two writes, which opens up a race if another vcpu accesses the same memory area. Fix by calling set_shadow_pte() instead of assigning directly. Noticed by Izik Eidus. Signed-off-by: Avi Kivity <avi@qumranet.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kvm/mmu.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 7f57da66382..b0e4ddca6c1 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1189,9 +1189,10 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t v, int write,
return -ENOMEM;
}
- table[index] = __pa(new_table->spt)
- | PT_PRESENT_MASK | PT_WRITABLE_MASK
- | shadow_user_mask | shadow_x_mask;
+ set_shadow_pte(&table[index],
+ __pa(new_table->spt)
+ | PT_PRESENT_MASK | PT_WRITABLE_MASK
+ | shadow_user_mask | shadow_x_mask);
}
table_addr = table[index] & PT64_BASE_ADDR_MASK;
}