diff options
| -rw-r--r-- | 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 892a7a60c81..57e76b37242 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -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) { |