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@xxxxxxx>
Signed-off-by: Amit Shah <amit.shah@xxxxxxxxxx>
Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
---
arch/x86/kvm/x86.c | 33 ++++++++++++++++++++++++++-------
1 files changed, 26 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 6025e5b..88e159c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2632,14 +2632,33 @@ 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) {
--
1.6.1.3
--
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