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 <t...@linutronix.de> Cc: Ingo Molnar <mi...@redhat.com> Cc: "H. Peter Anvin" <h...@zytor.com> Cc: Paolo Bonzini <pbonz...@redhat.com> Cc: "Radim Krčmář" <rkrc...@redhat.com> Cc: Joerg Roedel <j...@8bytes.org> Cc: Borislav Petkov <b...@suse.de> Cc: Tom Lendacky <thomas.lenda...@amd.com> Cc: x...@kernel.org Cc: k...@vger.kernel.org Cc: linux-kernel@vger.kernel.org Reviewed-by: Borislav Petkov <b...@suse.de> Signed-off-by: Brijesh Singh <brijesh.si...@amd.com> --- arch/x86/kvm/svm.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index f350e9bac9eb..3e848f952b4f 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -1443,8 +1443,10 @@ static void init_vmcb(struct vcpu_svm *svm) 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); -- 2.9.5