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-rw-r--r--arch/x86/include/asm/kvm_emulate.h13
-rw-r--r--arch/x86/kvm/emulate.c51
2 files changed, 64 insertions, 0 deletions
diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index c8b2868..7b9cfc4 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -301,6 +301,19 @@ struct x86_emulate_ctxt {
#define X86EMUL_MODE_PROT (X86EMUL_MODE_PROT16|X86EMUL_MODE_PROT32| \
X86EMUL_MODE_PROT64)
+/* 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
+
enum x86_intercept_stage {
X86_ICTP_NONE = 0, /* Allow zero-init to not match anything */
X86_ICPT_PRE_EXCEPT,
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 05a562b..0982507 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1891,6 +1891,51 @@ setup_syscalls_segments(struct x86_emulate_ctxt *ctxt,
ss->p = 1;
}
+static bool em_syscall_is_enabled(struct x86_emulate_ctxt *ctxt)
+{
+ struct x86_emulate_ops *ops = ctxt->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, &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 em_syscall(struct x86_emulate_ctxt *ctxt)
{
struct x86_emulate_ops *ops = ctxt->ops;
@@ -1904,9 +1949,15 @@ static int em_syscall(struct x86_emulate_ctxt *ctxt)
ctxt->mode == X86EMUL_MODE_VM86)
return emulate_ud(ctxt);
+ if (!(em_syscall_is_enabled(ctxt)))
+ return emulate_ud(ctxt);
+
ops->get_msr(ctxt, MSR_EFER, &efer);
setup_syscalls_segments(ctxt, &cs, &ss);
+ if (!(efer & EFER_SCE))
+ return emulate_ud(ctxt);
+
ops->get_msr(ctxt, MSR_STAR, &msr_data);
msr_data >>= 32;
cs_sel = (u16)(msr_data & 0xfffc);