From cc70e7374df1e3a56d718e8ca330619f316511a6 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Thu, 11 Oct 2007 15:12:24 +0200 Subject: [PATCH] KVM: MMU: Disable write access on clean large pages 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 --- drivers/kvm/paging_tmpl.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h index e07cb2e..4538b15 100644 --- a/drivers/kvm/paging_tmpl.h +++ b/drivers/kvm/paging_tmpl.h @@ -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); -- 2.7.4