[PATCH 4.9 106/129] KVM: x86: set ctxt->have_exception in x86_decode_insn()

[Greg Kroah-Hartman]

From: Jan Dakinevich <jan.dakinev...@virtuozzo.com>

commit c8848cee74ff05638e913582a476bde879c968ad upstream.

x86_emulate_instruction() takes into account ctxt->have_exception flag
during instruction decoding, but in practice this flag is never set in
x86_decode_insn().

Fixes: 6ea6e84309ca ("KVM: x86: inject exceptions produced by x86_decode_insn")
Cc: sta...@vger.kernel.org
Cc: Denis Lunev <d...@virtuozzo.com>
Cc: Roman Kagan <rka...@virtuozzo.com>
Cc: Denis Plotnikov <dplotni...@virtuozzo.com>
Signed-off-by: Jan Dakinevich <jan.dakinev...@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 arch/x86/kvm/emulate.c |    2 ++
 arch/x86/kvm/x86.c     |    6 ++++++
 2 files changed, 8 insertions(+)

--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -5257,6 +5257,8 @@ done_prefixes:
                                        ctxt->memopp->addr.mem.ea + ctxt->_eip);
 
 done:
+       if (rc == X86EMUL_PROPAGATE_FAULT)
+               ctxt->have_exception = true;
        return (rc != X86EMUL_CONTINUE) ? EMULATION_FAILED : EMULATION_OK;
 }
 
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5765,6 +5765,12 @@ int x86_emulate_instruction(struct kvm_v
                                                emulation_type))
                                return EMULATE_DONE;
                        if (ctxt->have_exception) {
+                               /*
+                                * #UD should result in just EMULATION_FAILED, 
and trap-like
+                                * exception should not be encountered during 
decode.
+                                */
+                               WARN_ON_ONCE(ctxt->exception.vector == 
UD_VECTOR ||
+                                            
exception_type(ctxt->exception.vector) == EXCPT_TRAP);
                                inject_emulated_exception(vcpu);
                                return EMULATE_DONE;
                        }