[34-longterm 078/196] x86, cpu: Fix regression in AMD errata checking code

[Paul Gortmaker]

From: Hans Rosenfeld <hans.rosenfeld@xxxxxxx>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    If you see a problem with using this for longterm, please comment.
                   -------------------

commit 07a7795ca2e6e66d00b184efb46bd0e23d90d3fe upstream.

A bug in the family-model-stepping matching code caused the presence of
errata to go undetected when OSVW was not used. This causes hangs on
some K8 systems because the E400 workaround is not enabled.

Signed-off-by: Hans Rosenfeld <hans.rosenfeld@xxxxxxx>
LKML-Reference: <1282141190-930137-1-git-send-email-hans.rosenfeld@xxxxxxx>
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
 arch/x86/kernel/cpu/amd.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index dba9ca2..d618dc1 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -688,7 +688,7 @@ bool cpu_has_amd_erratum(const int *erratum)
 	}
 
 	/* OSVW unavailable or ID unknown, match family-model-stepping range */
-	ms = (cpu->x86_model << 8) | cpu->x86_mask;
+	ms = (cpu->x86_model << 4) | cpu->x86_mask;
 	while ((range = *erratum++))
 		if ((cpu->x86 == AMD_MODEL_RANGE_FAMILY(range)) &&
 		    (ms >= AMD_MODEL_RANGE_START(range)) &&
-- 
1.7.9.3

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