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KVM: Allow emulation of syscalls instructions on #UD 

Add the opcodes for syscall, sysenter and sysexit to the list of instructions
handled by the undefined opcode handler.

Signed-off-by: Christoph Egger <christoph.egger@amd.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Andre Przywara 2009-06-17 15:50:31 +02:00 committed by Avi Kivity
parent 229456fc34
commit 0cb5762ed2
1 changed files with 26 additions and 7 deletions
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33
arch/x86/kvm/x86.c
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@ -2667,14 +2667,33 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
r = x86_decode_insn(&vcpu->arch.emulate_ctxt, &emulate_ops);
/* Reject the instructions other than VMCALL/VMMCALL when
* try to emulate invalid opcode */
/* Only allow emulation of specific instructions on #UD
* (namely VMMCALL, sysenter, sysexit, syscall)*/
c = &vcpu->arch.emulate_ctxt.decode;
if ((emulation_type & EMULTYPE_TRAP_UD) &&
(!(c->twobyte && c->b == 0x01 &&
(c->modrm_reg == 0 || c->modrm_reg == 3) &&
c->modrm_mod == 3 && c->modrm_rm == 1)))
return EMULATE_FAIL;
if (emulation_type & EMULTYPE_TRAP_UD) {
if (!c->twobyte)
return EMULATE_FAIL;
switch (c->b) {
case 0x01: /* VMMCALL */
if (c->modrm_mod != 3 || c->modrm_rm != 1)
return EMULATE_FAIL;
break;
case 0x34: /* sysenter */
case 0x35: /* sysexit */
if (c->modrm_mod != 0 || c->modrm_rm != 0)
return EMULATE_FAIL;
break;
case 0x05: /* syscall */
if (c->modrm_mod != 0 || c->modrm_rm != 0)
return EMULATE_FAIL;
break;
default:
return EMULATE_FAIL;
}
if (!(c->modrm_reg == 0 || c->modrm_reg == 3))
return EMULATE_FAIL;
}
++vcpu->stat.insn_emulation;
if (r) {