From 2acb16e5688a2a3dbeacd0f9e36ed95fe64380d4 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 22 Jun 2021 10:56:49 -0700 Subject: [PATCH] KVM: x86/mmu: Use MMU's role to detect CR4.SMEP value in nested NPT walk Use the MMU's role to get its effective SMEP value when injecting a fault into the guest. When walking L1's (nested) NPT while L2 is active, vCPU state will reflect L2, whereas NPT uses the host's (L1 in this case) CR0, CR4, EFER, etc... If L1 and L2 have different settings for SMEP and L1 does not have EFER.NX=1, this can result in an incorrect PFEC.FETCH when injecting #NPF. Fixes: 35a33e5bb1a3 ("KVM: Add instruction fetch checking when walking guest page table") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Message-Id: <20210622175739.3610207-5-seanjc@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/paging_tmpl.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h index 823a5919f9fa0..52fffd68b5229 100644 --- a/arch/x86/kvm/mmu/paging_tmpl.h +++ b/arch/x86/kvm/mmu/paging_tmpl.h @@ -471,8 +471,7 @@ retry_walk: error: errcode |= write_fault | user_fault; - if (fetch_fault && (mmu->nx || - kvm_read_cr4_bits(vcpu, X86_CR4_SMEP))) + if (fetch_fault && (mmu->nx || mmu->mmu_role.ext.cr4_smep)) errcode |= PFERR_FETCH_MASK; walker->fault.vector = PF_VECTOR; -- 2.39.5