linux-kernel - [PATCH 5.10 064/593] KVM: x86/mmu: Use MMUs role to detect CR4.SMEP value in nested NPT walk

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20210712060850.235380453@linuxfoundation.org>
Date:   Mon, 12 Jul 2021 08:03:44 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH 5.10 064/593] KVM: x86/mmu: Use MMUs role to detect CR4.SMEP value in nested NPT walk

From: Sean Christopherson <seanjc@...gle.com>

commit ef318b9edf66a082f23d00d79b70c17b4c055a26 upstream.

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: e57d4a356ad3 ("KVM: Add instruction fetch checking when walking guest page table")
Cc: stable@...r.kernel.org
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
Message-Id: <20210622175739.3610207-5-seanjc@...gle.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/kvm/mmu/paging_tmpl.h |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- 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;