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KVM: MMU: Disable write access on clean large pages

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By forcing clean huge pages to be read-only, we have separate roles
for the shadow of a clean large page and the shadow of a dirty large
page.  This is necessary because different ptes will be instantiated
for the two cases, even for read faults.

Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Avi Kivity 2007-10-11 15:12:24 +02:00
parent c22e3514fc
commit cc70e7374d
1 changed files with 2 additions and 0 deletions
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2
drivers/kvm/paging_tmpl.h
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@ -382,6 +382,8 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
metaphysical = 1;
hugepage_access = walker->pte;
hugepage_access &= PT_USER_MASK | PT_WRITABLE_MASK;
if (!is_dirty_pte(walker->pte))
hugepage_access &= ~PT_WRITABLE_MASK;
hugepage_access >>= PT_WRITABLE_SHIFT;
if (walker->pte & PT64_NX_MASK)
hugepage_access |= (1 << 2);