KVM: x86: set ctxt->have_exception in x86_decode_insn()

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: stable@vger.kernel.org
Cc: Denis Lunev <den@virtuozzo.com>
Cc: Roman Kagan <rkagan@virtuozzo.com>
Cc: Denis Plotnikov <dplotnikov@virtuozzo.com>
Signed-off-by: Jan Dakinevich <jan.dakinevich@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 5dd56e3..6c7847b 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -5245,6 +5245,8 @@ 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;
 }
 

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 393d984..441b8b7 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5487,6 +5487,12 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
                                                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;
                        }