KVM: x86: Add a macro to precisely handle aliased 0x1.EDX CPUID features

Add a macro to precisely handle CPUID features that AMD duplicated from
CPUID.0x1.EDX into CPUID.0x8000_0001.EDX.  This will allow adding an
assert that all features passed to kvm_cpu_cap_init() match the word being
processed, e.g. to prevent passing a feature from CPUID 0x7 to CPUID 0x1.

Because the kernel simply reuses the X86_FEATURE_* definitions from
CPUID.0x1.EDX, KVM's use of the aliased features would result in false
positives from such an assert.

No functional change intended.

Link: https://lore.kernel.org/r/20241128013424.4096668-26-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index bd1d54e25414e4ce9d0a6a609e50a590c6bd8f9c..11cd176a26f8fcb3f453db182391d0c6d2fa6733 100644 (file)
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -669,6 +669,16 @@ static __always_inline void kvm_cpu_cap_init(enum cpuid_leafs leaf, u32 mask)
        (IS_ENABLED(CONFIG_X86_64) ? F(name) : 0);              \
 })
 
+/*
+ * Aliased Features - For features in 0x8000_0001.EDX that are duplicates of
+ * identical 0x1.EDX features, and thus are aliased from 0x1 to 0x8000_0001.
+ */
+#define ALIASED_1_EDX_F(name)                                                  \
+({                                                                             \
+       BUILD_BUG_ON(__feature_leaf(X86_FEATURE_##name) != CPUID_1_EDX);        \
+       feature_bit(name);                                                      \
+})
+
 void kvm_set_cpu_caps(void)
 {
        memset(kvm_cpu_caps, 0, sizeof(kvm_cpu_caps));
@@ -913,30 +923,30 @@ void kvm_set_cpu_caps(void)
        );
 
        kvm_cpu_cap_init(CPUID_8000_0001_EDX,
-               F(FPU) |
-               F(VME) |
-               F(DE) |
-               F(PSE) |
-               F(TSC) |
-               F(MSR) |
-               F(PAE) |
-               F(MCE) |
-               F(CX8) |
-               F(APIC) |
+               ALIASED_1_EDX_F(FPU) |
+               ALIASED_1_EDX_F(VME) |
+               ALIASED_1_EDX_F(DE) |
+               ALIASED_1_EDX_F(PSE) |
+               ALIASED_1_EDX_F(TSC) |
+               ALIASED_1_EDX_F(MSR) |
+               ALIASED_1_EDX_F(PAE) |
+               ALIASED_1_EDX_F(MCE) |
+               ALIASED_1_EDX_F(CX8) |
+               ALIASED_1_EDX_F(APIC) |
                0 /* Reserved */ |
                F(SYSCALL) |
-               F(MTRR) |
-               F(PGE) |
-               F(MCA) |
-               F(CMOV) |
-               F(PAT) |
-               F(PSE36) |
+               ALIASED_1_EDX_F(MTRR) |
+               ALIASED_1_EDX_F(PGE) |
+               ALIASED_1_EDX_F(MCA) |
+               ALIASED_1_EDX_F(CMOV) |
+               ALIASED_1_EDX_F(PAT) |
+               ALIASED_1_EDX_F(PSE36) |
                0 /* Reserved */ |
                F(NX) |
                0 /* Reserved */ |
                F(MMXEXT) |
-               F(MMX) |
-               F(FXSR) |
+               ALIASED_1_EDX_F(MMX) |
+               ALIASED_1_EDX_F(FXSR) |
                F(FXSR_OPT) |
                X86_64_F(GBPAGES) |
                F(RDTSCP) |
@@ -1076,6 +1086,7 @@ EXPORT_SYMBOL_GPL(kvm_set_cpu_caps);
 #undef F
 #undef SF
 #undef X86_64_F
+#undef ALIASED_1_EDX_F
 
 struct kvm_cpuid_array {
        struct kvm_cpuid_entry2 *entries;