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

Pull x86 fixes from Ingo Molnar:
 "Two fixes: a quirk for KVM guests running on certain AMD CPUs, and a
  KASAN related build fix"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/CPU/AMD: Don't force the CPB cap when running under a hypervisor
  x86/boot: Provide KASAN compatible aliases for string routines

2 files changed, 15 insertions, 6 deletions

diff --git a/arch/x86/boot/compressed/string.c b/arch/x86/boot/compressed/string.c
index 19dbbcdd1a53..81fc1eaa3229 100644
--- a/arch/x86/boot/compressed/string.c
+++ b/arch/x86/boot/compressed/string.c
@@ -11,7 +11,7 @@
 #include "../string.c"
 
 #ifdef CONFIG_X86_32
-static void *__memcpy(void *dest, const void *src, size_t n)
+static void *____memcpy(void *dest, const void *src, size_t n)
 {
         int d0, d1, d2;
         asm volatile(
@@ -25,7 +25,7 @@ static void *__memcpy(void *dest, const void *src, size_t n)
         return dest;
 }
 #else
-static void *__memcpy(void *dest, const void *src, size_t n)
+static void *____memcpy(void *dest, const void *src, size_t n)
 {
         long d0, d1, d2;
         asm volatile(
@@ -56,7 +56,7 @@ void *memmove(void *dest, const void *src, size_t n)
         const unsigned char *s = src;
 
         if (d <= s || d - s >= n)
-                return __memcpy(dest, src, n);
+                return ____memcpy(dest, src, n);
 
         while (n-- > 0)
                 d[n] = s[n];
@@ -71,5 +71,11 @@ void *memcpy(void *dest, const void *src, size_t n)
                 warn("Avoiding potentially unsafe overlapping memcpy()!");
                 return memmove(dest, src, n);
         }
-        return __memcpy(dest, src, n);
+        return ____memcpy(dest, src, n);
 }
+
+#ifdef CONFIG_KASAN
+extern void *__memset(void *s, int c, size_t n) __alias(memset);
+extern void *__memmove(void *dest, const void *src, size_t n) __alias(memmove);
+extern void *__memcpy(void *dest, const void *src, size_t n) __alias(memcpy);
+#endif
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 80a405c2048a..8d4e50428b68 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -824,8 +824,11 @@ static void init_amd_zn(struct cpuinfo_x86 *c)
 {
         set_cpu_cap(c, X86_FEATURE_ZEN);
 
-        /* Fix erratum 1076: CPB feature bit not being set in CPUID. */
-        if (!cpu_has(c, X86_FEATURE_CPB))
+        /*
+         * Fix erratum 1076: CPB feature bit not being set in CPUID.
+         * Always set it, except when running under a hypervisor.
+         */
+        if (!cpu_has(c, X86_FEATURE_HYPERVISOR) && !cpu_has(c, X86_FEATURE_CPB))
                 set_cpu_cap(c, X86_FEATURE_CPB);
 }