KVM: x86: Fix device passthrough when SME is active

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=daaf216c06fba4ee4dc3f62715667da929d68774
Commit:     daaf216c06fba4ee4dc3f62715667da929d68774
Parent:     52be7a467e4b45b0d8d3b700729fc65a9b8ebc94
Author:     Tom Lendacky <thomas.lendacky at amd.com>
AuthorDate: Thu Mar 8 17:17:31 2018 -0600
Committer:  Paolo Bonzini <pbonzini at redhat.com>
CommitDate: Fri Mar 16 14:32:23 2018 +0100

    KVM: x86: Fix device passthrough when SME is active
    
    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 at vger.kernel.org> # 4.14.x-
    Signed-off-by: Tom Lendacky <thomas.lendacky at amd.com>
    Signed-off-by: Paolo Bonzini <pbonzini at redhat.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 f551962ac294..763bb3bade63 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) {