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KVM: x86: Emulator mis-decodes VEX instructions on real-mode 

Commit 7fe864dc94 (KVM: x86: Mark VEX-prefix instructions emulation as
unimplemented, 2014-06-02) marked VEX instructions as such in protected
mode.  VEX-prefix instructions are not supported relevant on real-mode
and VM86, but should cause #UD instead of being decoded as LES/LDS.

Fix this behaviour to be consistent with real hardware.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
[Check for mod == 3, rather than 2 or 3. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Nadav Amit 2014-11-02 11:54:58 +02:00 committed by Paolo Bonzini
parent 2c2ca2d12f
commit d14cb5df59
1 changed files with 1 additions and 2 deletions
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3
arch/x86/kvm/emulate.c
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@ -4517,8 +4517,7 @@ done_prefixes:
/* 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)))) {
(mode == X86EMUL_MODE_PROT64 || (ctxt->modrm & 0xc0) == 0xc0)) {
ctxt->d = NotImpl;
}