From 8e8da023f5af71662867729db5547dc54786093c Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 4 Dec 2011 11:57:09 -0800 Subject: [PATCH] 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 Tested-by: Bob Tracy Acked-by: Borislav Petkov Cc: Ingo Molnar Cc: Srivatsa S. Bhat Signed-off-by: Linus Torvalds --- arch/x86/kernel/cpu/amd.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index c7e46cb..0bab2b1 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; - early_init_amd_mc(c); /* @@ -473,12 +471,12 @@ static void __cpuinit early_init_amd(struct cpuinfo_x86 *c) set_cpu_cap(c, X86_FEATURE_EXTD_APICID); } #endif - - rdmsr_safe(MSR_AMD64_PATCH_LEVEL, &c->microcode, &dummy); } static void __cpuinit init_amd(struct cpuinfo_x86 *c) { + u32 dummy; + #ifdef CONFIG_SMP 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 -- 2.7.4