From: Brijesh Singh <brijesh.singh@amd.com>
Date: Mon, 4 Dec 2017 10:57:39 -0600
Subject: KVM: SVM: Do not install #UD intercept when SEV is enabled
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Git-commit: 35c6f649bbb2e3f367116307273f998f0bf3e08e
Patch-mainline: v4.16-rc1
References: bsc#1063068
On #UD, x86_emulate_instruction() fetches the data from guest memory and
decodes the instruction bytes to assist further. When SEV is enabled, the
instruction bytes will be encrypted using the guest-specific key and the
hypervisor will no longer able to fetch the instruction bytes to assist
UD handling. By not installing intercept we let the guest receive and
handle #UD.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: x86@kernel.org
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Acked-by: Borislav Petkov <bp@suse.de>
---
arch/x86/kvm/svm.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1442,8 +1442,10 @@ static void init_vmcb(struct vcpu_svm *s
svm->vmcb->control.int_ctl |= V_GIF_ENABLE_MASK;
}
- if (sev_guest(svm->vcpu.kvm))
+ if (sev_guest(svm->vcpu.kvm)) {
svm->vmcb->control.nested_ctl |= SVM_NESTED_CTL_SEV_ENABLE;
+ clr_exception_intercept(svm, UD_VECTOR);
+ }
mark_all_dirty(svm->vmcb);