path: root/arch
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authorLinus Torvalds <torvalds@linux-foundation.org>2011-12-04 11:57:09 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2011-12-04 11:57:09 -0800
commit8e8da023f5af71662867729db5547dc54786093c (patch)
tree0108c8b0bac10268a3156aaf042466b8815d1330 /arch
parente5fd47bfab2df0c2184cc0bf4245d8e1bb7724fb (diff)
x86: Fix boot failures on older AMD CPU's
People with old AMD chips are getting hung boots, because commit bcb80e53877c ("x86, microcode, AMD: Add microcode revision to /proc/cpuinfo") moved the microcode detection too early into "early_init_amd()". At that point we are *so* early in the booth that the exception tables haven't even been set up yet, so the whole rdmsr_safe(MSR_AMD64_PATCH_LEVEL, &c->microcode, &dummy); doesn't actually work: if the rdmsr does a GP fault (due to non-existant MSR register on older CPU's), we can't fix it up yet, and the boot fails. Fix it by simply moving the code to a slightly later point in the boot (init_amd() instead of early_init_amd()), since the kernel itself doesn't even really care about the microcode patchlevel at this point (or really ever: it's made available to user space in /proc/cpuinfo, and updated if you do a microcode load). Reported-tested-and-bisected-by: Larry Finger <Larry.Finger@lwfinger.net> Tested-by: Bob Tracy <rct@gherkin.frus.com> Acked-by: Borislav Petkov <borislav.petkov@amd.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch')
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index c7e46cb3532..0bab2b18bb2 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -442,8 +442,6 @@ static void __cpuinit bsp_init_amd(struct cpuinfo_x86 *c)
static void __cpuinit early_init_amd(struct cpuinfo_x86 *c)
- u32 dummy;
@@ -473,12 +471,12 @@ static void __cpuinit early_init_amd(struct cpuinfo_x86 *c)
set_cpu_cap(c, X86_FEATURE_EXTD_APICID);
- rdmsr_safe(MSR_AMD64_PATCH_LEVEL, &c->microcode, &dummy);
static void __cpuinit init_amd(struct cpuinfo_x86 *c)
+ u32 dummy;
unsigned long long value;
@@ -657,6 +655,8 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c)
checking_wrmsrl(MSR_AMD64_MCx_MASK(4), mask);
+ rdmsr_safe(MSR_AMD64_PATCH_LEVEL, &c->microcode, &dummy);
#ifdef CONFIG_X86_32