KVM: x86 emulator: fix handling for unemulated instructions

If an instruction is present in the decode tables but not in the execution
switch, it will be emulated as a NOP.  An example is IRET (0xcf).

Fix by adding default: labels to the execution switches.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 66ca98aafdd6..70e47d3593d8 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -3028,6 +3028,8 @@ special_insn:
                 if (c->modrm_reg == 5)
                         goto jump_far;
                 goto grp45;
+        default:
+                goto cannot_emulate;
         }
 
 writeback:
@@ -3353,6 +3355,8 @@ twobyte_insn:
                 if (rc != X86EMUL_CONTINUE)
                         goto done;
                 break;
+        default:
+                goto cannot_emulate;
         }
         goto writeback;