From 6aa0b9dec5d6dde26ea17b0b5be8fccfe19df3c9 Mon Sep 17 00:00:00 2001 From: Xiao Guangrong Date: Wed, 30 Jun 2010 16:02:45 +0800 Subject: [PATCH] KVM: MMU: fix conflict access permissions in direct sp In no-direct mapping, we mark sp is 'direct' when we mapping the guest's larger page, but its access is encoded form upper page-struct entire not include the last mapping, it will cause access conflict. For example, have this mapping: [W] / PDE1 -> |---| P[W] | | LPA \ PDE2 -> |---| [R] P have two children, PDE1 and PDE2, both PDE1 and PDE2 mapping the same lage page(LPA). The P's access is WR, PDE1's access is WR, PDE2's access is RO(just consider read-write permissions here) When guest access PDE1, we will create a direct sp for LPA, the sp's access is from P, is W, then we will mark the ptes is W in this sp. Then, guest access PDE2, we will find LPA's shadow page, is the same as PDE's, and mark the ptes is RO. So, if guest access PDE1, the incorrect #PF is occured. Fixed by encode the last mapping access into direct shadow page Signed-off-by: Xiao Guangrong Signed-off-by: Marcelo Tosatti Signed-off-by: Avi Kivity --- arch/x86/kvm/paging_tmpl.h | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index 89d66ca4d87c..2331bdc2b549 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -342,6 +342,7 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, /* advance table_gfn when emulating 1gb pages with 4k */ if (delta == 0) table_gfn += PT_INDEX(addr, level); + access &= gw->pte_access; } else { direct = 0; table_gfn = gw->table_gfn[level - 2]; -- 2.20.1