x86/CPU: Add native CPUID variants returning a single datum

... similarly to the cpuid_<reg>() variants.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/20170109114147.5082-2-bp@alien8.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 18 insertions, 0 deletions

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index eaf100508c36..1be64da0384e 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -219,6 +219,24 @@ static inline void native_cpuid(unsigned int *eax, unsigned int *ebx,
             : "memory");
 }
 
+#define native_cpuid_reg(reg)                                   \
+static inline unsigned int native_cpuid_##reg(unsigned int op)  \
+{                                                               \
+        unsigned int eax = op, ebx, ecx = 0, edx;               \
+                                                                \
+        native_cpuid(&eax, &ebx, &ecx, &edx);                   \
+                                                                \
+        return reg;                                             \
+}
+
+/*
+ * Native CPUID functions returning a single datum.
+ */
+native_cpuid_reg(eax)
+native_cpuid_reg(ebx)
+native_cpuid_reg(ecx)
+native_cpuid_reg(edx)
+
 static inline void load_cr3(pgd_t *pgdir)
 {
         write_cr3(__pa(pgdir));