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

commit 61cb57c9ed631c95b54f8e9090c89d18b3695b3c upstream.

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>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 4fbf0c9..23f1a6b 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2149,6 +2149,8 @@ static int ud_interception(struct vcpu_svm *svm)
        int er;
 
        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 0f0b27d..f0d3de1 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5502,6 +5502,8 @@ static int handle_exception(struct kvm_vcpu *vcpu)
                        return 1;
                }
                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;