From: Liran Alon <liran.alon@oracle.com>
Date: Sun, 5 Nov 2017 16:56:32 +0200
Subject: KVM: x86: Exit to user-mode on #UD intercept when emulator requires
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Patch-mainline: v4.15-rc2
Git-commit: 61cb57c9ed631c95b54f8e9090c89d18b3695b3c
References: bsc#1077761

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>
Acked-by: Alexander Graf <agraf@suse.de>
---
 arch/x86/kvm/svm.c |    2 ++
 arch/x86/kvm/vmx.c |    2 ++
 2 files changed, 4 insertions(+)

--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2203,6 +2203,8 @@
 
 	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;
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5909,6 +5909,8 @@
 	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;