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Subject[PATCH 4.9 106/129] KVM: x86: set ctxt->have_exception in x86_decode_insn()
Date
From: Jan Dakinevich <jan.dakinevich@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: 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>

---
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;
}

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