x86: Introduce hypervisor_cpuid_base()
This patch introduce hypervisor_cpuid_base() which loop test the hypervisor
existence function until the signature match and check the number of leaves if
required. This could be used by Xen/KVM guest to detect the existence of
hypervisor.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: http://lkml.kernel.org/r/1374742475-2485-1-git-send-email-jasowang@redhat.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 24cf5ae..7763307 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -971,6 +971,21 @@
return ratio;
}
+static inline uint32_t hypervisor_cpuid_base(const char *sig, uint32_t leaves)
+{
+ uint32_t base, eax, signature[3];
+
+ for (base = 0x40000000; base < 0x40010000; base += 0x100) {
+ cpuid(base, &eax, &signature[0], &signature[1], &signature[2]);
+
+ if (!memcmp(sig, signature, 12) &&
+ (leaves == 0 || ((eax - base) >= leaves)))
+ return base;
+ }
+
+ return 0;
+}
+
extern unsigned long arch_align_stack(unsigned long sp);
extern void free_init_pages(char *what, unsigned long begin, unsigned long end);