i386: Clear MCE flag on AMD K6

It reports machine check capability in CPUID, but doesn't actually
implement all the necessary MSRs of the standard Intel machine
check architecture.

This fixes a boot failure on K6s recently introduced.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 7 insertions, 3 deletions

diff --git a/arch/i386/kernel/cpu/amd.c b/arch/i386/kernel/cpu/amd.c
index 4fec702afd7e..6f47eeeb93ea 100644
--- a/arch/i386/kernel/cpu/amd.c
+++ b/arch/i386/kernel/cpu/amd.c
@@ -280,6 +280,10 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c)
 
         if (c->x86 == 0x10 && !force_mwait)
                 clear_bit(X86_FEATURE_MWAIT, c->x86_capability);
+
+        /* K6s reports MCEs but don't actually have all the MSRs */
+        if (c->x86 < 6)
+                clear_bit(X86_FEATURE_MCE, c->x86_capability);
 }
 
 static unsigned int __cpuinit amd_size_cache(struct cpuinfo_x86 * c, unsigned int size)
diff --git a/arch/i386/kernel/cpu/mcheck/k7.c b/arch/i386/kernel/cpu/mcheck/k7.c
index f9fa4142551e..eef63e3630c2 100644
--- a/arch/i386/kernel/cpu/mcheck/k7.c
+++ b/arch/i386/kernel/cpu/mcheck/k7.c
@@ -72,12 +72,12 @@ void amd_mcheck_init(struct cpuinfo_x86 *c)
         u32 l, h;
         int i;
 
-        machine_check_vector = k7_machine_check;
-        wmb();
-
         if (!cpu_has(c, X86_FEATURE_MCE))
                 return;
 
+        machine_check_vector = k7_machine_check;
+        wmb();
+
         printk (KERN_INFO "Intel machine check architecture supported.\n");
         rdmsr (MSR_IA32_MCG_CAP, l, h);
         if (l & (1<<8)) /* Control register present ? */