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KVM: MMU: Set nx bit correctly on shadow ptes

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While the page table walker correctly generates a guest page fault
if a guest tries to execute a non-executable page, the shadow code does
not mark it non-executable.  This means that if a guest accesses an nx
page first with a read access, then subsequent code fetch accesses will
succeed.

Fix by setting the nx bit on shadow ptes.

Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Avi Kivity 2007-12-09 16:37:36 +02:00
parent fe135d2ceb
commit 8d87a03aea
1 changed files with 2 additions and 0 deletions
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2
drivers/kvm/paging_tmpl.h
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@ -255,6 +255,8 @@ static void FNAME(set_pte)(struct kvm_vcpu *vcpu, pt_element_t gpte,
spte |= gpte & PT64_NX_MASK;
if (!dirty)
pte_access &= ~ACC_WRITE_MASK;
if (!(pte_access & ACC_EXEC_MASK))
spte |= PT64_NX_MASK;
page = gfn_to_page(vcpu->kvm, gfn);