[PATCH] KVM: x86: Fix device passthrough when SME is active

From: Tom Lendacky <thomas.lendacky@amd.com>
To: x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: "Brijesh Singh" <brijesh.singh@amd.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Joerg Roedel" <joro@8bytes.org>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Borislav Petkov" <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Thomas Gleixner" <tglx@linutronix.de>
Subject: [PATCH] KVM: x86: Fix device passthrough when SME is active
Date: Thu, 08 Mar 2018 17:17:31 -0600	[thread overview]
Message-ID: <20180308231731.27881.84826.stgit@tlendack-t1.amdoffice.net> (raw)

When using device passthrough with SME active, the MMIO range that is
mapped for the device should not be mapped encrypted.  Add a check in
set_spte() to insure that a page is not mapped encrypted if that page
is a device MMIO page as indicated by kvm_is_mmio_pfn().

Cc: <stable@vger.kernel.org> # 4.14.x-
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 arch/x86/kvm/mmu.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index f551962..763bb3b 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2770,8 +2770,10 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 	else
 		pte_access &= ~ACC_WRITE_MASK;
 
+	if (!kvm_is_mmio_pfn(pfn))
+		spte |= shadow_me_mask;
+
 	spte |= (u64)pfn << PAGE_SHIFT;
-	spte |= shadow_me_mask;
 
 	if (pte_access & ACC_WRITE_MASK) {
 
