[PATCH v2 5/7] KVM: x86: Add build-time assertions on validity of vendor strings

Sean Christopherson
2020-03-05T01:35:03Z

Add build-time assertions on the transcoded ASCII->u32 values for the
vendor strings. The u32 values are inscrutable, and to make things
worse, the order of registers used to build the strings is B->D->C,
i.e. completely illogical.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/kvm/emulate.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 9cf303984fe5..7391e1471e53 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -3952,6 +3952,26 @@ static int em_cpuid(struct x86_emulate_ctxt *ctxt)
u32 eax, ebx, ecx, edx;
u64 msr = 0;

+ BUILD_BUG_ON(X86EMUL_CPUID_VENDOR_AuthenticAMD_ebx != *(u32 *)"Auth" ||
+ X86EMUL_CPUID_VENDOR_AuthenticAMD_edx != *(u32 *)"enti" ||
+ X86EMUL_CPUID_VENDOR_AuthenticAMD_ecx != *(u32 *)"cAMD");
+
+ BUILD_BUG_ON(X86EMUL_CPUID_VENDOR_AMDisbetterI_ebx != *(u32 *)"AMDi" ||
+ X86EMUL_CPUID_VENDOR_AMDisbetterI_edx != *(u32 *)"sbet" ||
+ X86EMUL_CPUID_VENDOR_AMDisbetterI_ecx != *(u32 *)"ter!");
+
+ BUILD_BUG_ON(X86EMUL_CPUID_VENDOR_HygonGenuine_ebx != *(u32 *)"Hygo" ||
+ X86EMUL_CPUID_VENDOR_HygonGenuine_edx != *(u32 *)"nGen" ||
+ X86EMUL_CPUID_VENDOR_HygonGenuine_ecx != *(u32 *)"uine");
+
+ BUILD_BUG_ON(X86EMUL_CPUID_VENDOR_GenuineIntel_ebx != *(u32 *)"Genu" ||
+ X86EMUL_CPUID_VENDOR_GenuineIntel_edx != *(u32 *)"ineI" ||
+ X86EMUL_CPUID_VENDOR_GenuineIntel_ecx != *(u32 *)"ntel");
+
+ BUILD_BUG_ON(X86EMUL_CPUID_VENDOR_CentaurHauls_ebx != *(u32 *)"Cent" ||
+ X86EMUL_CPUID_VENDOR_CentaurHauls_edx != *(u32 *)"aurH" ||
+ X86EMUL_CPUID_VENDOR_CentaurHauls_ecx != *(u32 *)"auls");
+
ctxt->ops->get_msr(ctxt, MSR_MISC_FEATURES_ENABLES, &msr);
if (msr & MSR_MISC_FEATURES_ENABLES_CPUID_FAULT &&
ctxt->ops->cpl(ctxt)) {
--
2.24.1