Merge branch 'x86-paravirt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 paravirt changes from Ingo Molnar:
 "Hypervisor signature detection cleanup and fixes - the goal is to make
  KVM guests run better on MS/Hyperv and to generalize and factor out
  the code a bit"

* 'x86-paravirt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86: Correctly detect hypervisor
  x86, kvm: Switch to use hypervisor_cpuid_base()
  xen: Switch to use hypervisor_cpuid_base()
  x86: Introduce hypervisor_cpuid_base()

1 files changed, 15 insertions, 0 deletions

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 4c2d31d..987c75e 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -942,6 +942,21 @@ extern int set_tsc_mode(unsigned int val);
 
 extern u16 amd_get_nb_id(int cpu);
 
+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);