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 <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: "Radim Krčmář" <[email protected]> Cc: Joerg Roedel <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Tom Lendacky <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Reviewed-by: Borislav Petkov <[email protected]> Signed-off-by: Brijesh Singh <[email protected]> --- 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 b9906cb59238..d997f63c765d 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -1437,8 +1437,10 @@ 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
