KVM: x86: Exit to user-mode on #UD intercept when emulator requires

Instruction emulation after trapping a #UD exception can result in an
MMIO access, for example when emulating a MOVBE on a processor that
doesn't support the instruction.  In this case, the #UD vmexit handler
must exit to user mode, but there wasn't any code to do so.  Add it for
both VMX and SVM.

Signed-off-by: Liran Alon <liran.alon@oracle.com>
Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Wanpeng Li <wanpeng.li@hotmail.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 1bf7c09..eb714f1 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2204,6 +2204,8 @@ static int ud_interception(struct vcpu_svm *svm)
 
        WARN_ON_ONCE(is_guest_mode(&svm->vcpu));
        er = emulate_instruction(&svm->vcpu, EMULTYPE_TRAP_UD);
+       if (er == EMULATE_USER_EXIT)
+               return 0;
        if (er != EMULATE_DONE)
                kvm_queue_exception(&svm->vcpu, UD_VECTOR);
        return 1;

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index d319e26..65f1f06 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5919,6 +5919,8 @@ static int handle_exception(struct kvm_vcpu *vcpu)
        if (is_invalid_opcode(intr_info)) {
                WARN_ON_ONCE(is_guest_mode(vcpu));
                er = emulate_instruction(vcpu, EMULTYPE_TRAP_UD);
+               if (er == EMULATE_USER_EXIT)
+                       return 0;
                if (er != EMULATE_DONE)
                        kvm_queue_exception(vcpu, UD_VECTOR);
                return 1;