KVM: x86: Mark VEX-prefix instructions emulation as unimplemented

Currently the emulator does not recognize vex-prefix instructions.  However, it
may incorrectly decode lgdt/lidt instructions and try to execute them. This
patch returns unhandlable error on their emulation.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index e4e833d..8ec4a3e 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -4314,6 +4314,13 @@ done_prefixes:
        if (ctxt->d & ModRM)
                ctxt->modrm = insn_fetch(u8, ctxt);
 
+       /* vex-prefix instructions are not implemented */
+       if (ctxt->opcode_len == 1 && (ctxt->b == 0xc5 || ctxt->b == 0xc4) &&
+           (mode == X86EMUL_MODE_PROT64 ||
+           (mode >= X86EMUL_MODE_PROT16 && (ctxt->modrm & 0x80)))) {
+               ctxt->d = NotImpl;
+       }
+
        while (ctxt->d & GroupMask) {
                switch (ctxt->d & GroupMask) {
                case Group: