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KVM: MMU: Don't cache guest access bits in the shadow page table 

This was once used to avoid accessing the guest pte when upgrading
the shadow pte from read-only to read-write.  But usually we need
to set the guest pte dirty or accessed bits anyway, so this wasn't
really exploited.

Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Avi Kivity 2007-05-31 18:24:09 +03:00
parent fd97dc516c
commit b64b3763a5
2 changed files with 0 additions and 9 deletions
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8
drivers/kvm/mmu.c
View File

@ -97,14 +97,6 @@ static int dbg = 1;
#define PT_SHADOW_PS_MARK (1ULL << PT_FIRST_AVAIL_BITS_SHIFT)
#define PT_SHADOW_IO_MARK (1ULL << PT_FIRST_AVAIL_BITS_SHIFT)
#define PT_SHADOW_WRITABLE_SHIFT (PT_FIRST_AVAIL_BITS_SHIFT + 1)
#define PT_SHADOW_WRITABLE_MASK (1ULL << PT_SHADOW_WRITABLE_SHIFT)
#define PT_SHADOW_USER_SHIFT (PT_SHADOW_WRITABLE_SHIFT + 1)
#define PT_SHADOW_USER_MASK (1ULL << (PT_SHADOW_USER_SHIFT))
#define PT_SHADOW_BITS_OFFSET (PT_SHADOW_WRITABLE_SHIFT - PT_WRITABLE_SHIFT)
#define VALID_PAGE(x) ((x) != INVALID_PAGE)
#define PT64_LEVEL_BITS 9

1
drivers/kvm/paging_tmpl.h
View File

@ -219,7 +219,6 @@ static void FNAME(set_pte_common)(struct kvm_vcpu *vcpu,
spte |= PT_PRESENT_MASK | PT_ACCESSED_MASK | PT_DIRTY_MASK;
spte |= *gpte & PT64_NX_MASK;
spte |= access_bits << PT_SHADOW_BITS_OFFSET;
if (!dirty)
access_bits &= ~PT_WRITABLE_MASK;