@@ -228,6 +228,19 @@ struct x86_emulate_ctxt {
#define X86EMUL_MODE_PROT32 4 /* 32-bit protected mode. */
#define X86EMUL_MODE_PROT64 8 /* 64-bit (long) mode. */
+/* CPUID vendors */
+#define X86EMUL_CPUID_VENDOR_AuthenticAMD_ebx 0x68747541
+#define X86EMUL_CPUID_VENDOR_AuthenticAMD_ecx 0x444d4163
+#define X86EMUL_CPUID_VENDOR_AuthenticAMD_edx 0x69746e65
+
+#define X86EMUL_CPUID_VENDOR_AMDisbetterI_ebx 0x69444d41
+#define X86EMUL_CPUID_VENDOR_AMDisbetterI_ecx 0x21726574
+#define X86EMUL_CPUID_VENDOR_AMDisbetterI_edx 0x74656273
+
+#define X86EMUL_CPUID_VENDOR_GenuineIntel_ebx 0x756e6547
+#define X86EMUL_CPUID_VENDOR_GenuineIntel_ecx 0x6c65746e
+#define X86EMUL_CPUID_VENDOR_GenuineIntel_edx 0x49656e69
+
/* Host execution mode. */
#if defined(CONFIG_X86_32)
#define X86EMUL_MODE_HOST X86EMUL_MODE_PROT32
@@ -1842,12 +1842,58 @@ setup_syscalls_segments(struct x86_emulate_ctxt *ctxt,
ss->present = 1;
}
+static bool syscall_is_enabled(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops)
+{
+ u32 eax, ebx, ecx, edx;
+
+ /*
+ * syscall should always be enabled in longmode - so only become
+ * vendor specific (cpuid) if other modes are active...
+ */
+ if (ctxt->mode == X86EMUL_MODE_PROT64)
+ return true;
+
+ eax = 0x00000000;
+ ecx = 0x00000000;
+ if (ops->get_cpuid(ctxt->vcpu, &eax, &ebx, &ecx, &edx)) {
+ /*
+ * Intel ("GenuineIntel")
+ * remark: Intel CPUs only support "syscall" in 64bit
+ * longmode. Also an 64bit guest with a
+ * 32bit compat-app running will #UD !! While this
+ * behaviour can be fixed (by emulating) into AMD
+ * response - CPUs of AMD can't behave like Intel.
+ */
+ if (ebx == X86EMUL_CPUID_VENDOR_GenuineIntel_ebx &&
+ ecx == X86EMUL_CPUID_VENDOR_GenuineIntel_ecx &&
+ edx == X86EMUL_CPUID_VENDOR_GenuineIntel_edx)
+ return false;
+
+ /* AMD ("AuthenticAMD") */
+ if (ebx == X86EMUL_CPUID_VENDOR_AuthenticAMD_ebx &&
+ ecx == X86EMUL_CPUID_VENDOR_AuthenticAMD_ecx &&
+ edx == X86EMUL_CPUID_VENDOR_AuthenticAMD_edx)
+ return true;
+
+ /* AMD ("AMDisbetter!") */
+ if (ebx == X86EMUL_CPUID_VENDOR_AMDisbetterI_ebx &&
+ ecx == X86EMUL_CPUID_VENDOR_AMDisbetterI_ecx &&
+ edx == X86EMUL_CPUID_VENDOR_AMDisbetterI_edx)
+ return true;
+ }
+
+ /* default: (not Intel, not AMD), apply Intel's stricter rules... */
+ return false;
+}
+
static int
-emulate_syscall(struct x86_emulate_ctxt *ctxt)
+emulate_syscall(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
{
struct decode_cache *c = &ctxt->decode;
struct kvm_segment cs, ss;
u64 msr_data;
+ u64 efer = 0;
/* syscall is not available in real mode */
if (ctxt->mode == X86EMUL_MODE_REAL ||
@@ -1856,8 +1902,19 @@ emulate_syscall(struct x86_emulate_ctxt *ctxt)
return X86EMUL_PROPAGATE_FAULT;
}
+ if (!(syscall_is_enabled(ctxt, ops))) {
+ kvm_queue_exception(ctxt->vcpu, UD_VECTOR);
+ return X86EMUL_PROPAGATE_FAULT;
+ }
+
+ kvm_x86_ops->get_msr(ctxt->vcpu, MSR_EFER, &efer);
setup_syscalls_segments(ctxt, &cs, &ss);
+ if (!(efer & EFER_SCE)) {
+ kvm_queue_exception(ctxt->vcpu, UD_VECTOR);
+ return X86EMUL_PROPAGATE_FAULT;
+ }
+
kvm_x86_ops->get_msr(ctxt->vcpu, MSR_STAR, &msr_data);
msr_data >>= 32;
cs.selector = (u16)(msr_data & 0xfffc);
@@ -3062,7 +3119,7 @@ twobyte_insn:
}
break;
case 0x05: /* syscall */
- rc = emulate_syscall(ctxt);
+ rc = emulate_syscall(ctxt, ops);
if (rc != X86EMUL_CONTINUE)
goto done;
else