Messages in this thread Patch in this message | | | Date | Tue, 23 Jul 2013 19:40:49 +0200 | From | Torsten Kaiser <> | Subject | [PATCH v2] x86, AMD: Make cpu_has_amd_erratum() use the correct struct cpuinfo_x86 |
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cpu_has_amd_erratum() is buggy, because it uses the per-cpu cpu_info before it is filled by smp_store_boot_cpu_info() / smp_store_cpu_info().
If early microcode loading is enabled its collect_cpu_info_amd_early() will fill ->x86 and so the fallback to boot_cpu_data is not used. But ->x86_vendor was not filled and is still 0 == X86_VENDOR_INTEL resulting in no errata fixes getting applied and my system hangs on boot.
Using cpu_info in cpu_has_amd_erratum() is wrong anyway: Its only caller init_amd() will have a struct cpuinfo_x86 as parameter and the set_cpu_bug() that is controlled by cpu_has_amd_erratum() also only uses that struct.
So pass the struct cpuinfo_x86 from init_amd() to cpu_has_amd_erratum() and the broken fallback can be dropped.
I also added an WARN_ON() into the vendor check because init_amd() can only be used by AMD CPUs and if the current failure hadn't been silent this bug would have been much more obvious.
V2: At request of Borislav Petkov: BUG_ON -> WARN_ON and subject change
Signed-off-by: Torsten Kaiser <just.for.lkml@googlemail.com>
--- a/arch/x86/kernel/cpu/amd.c 2013-07-22 06:33:10.027931005 +0200 +++ b/arch/x86/kernel/cpu/amd.c 2013-07-22 06:35:15.757931265 +0200 @@ -512,7 +512,7 @@ static void early_init_amd(struct cpuinf static const int amd_erratum_383[]; static const int amd_erratum_400[]; -static bool cpu_has_amd_erratum(const int *erratum); +static bool cpu_has_amd_erratum(struct cpuinfo_x86 *cpu, const int *erratum); static void init_amd(struct cpuinfo_x86 *c) { @@ -729,11 +729,11 @@ static void init_amd(struct cpuinfo_x86 value &= ~(1ULL << 24); wrmsrl_safe(MSR_AMD64_BU_CFG2, value); - if (cpu_has_amd_erratum(amd_erratum_383)) + if (cpu_has_amd_erratum(c, amd_erratum_383)) set_cpu_bug(c, X86_BUG_AMD_TLB_MMATCH); } - if (cpu_has_amd_erratum(amd_erratum_400)) + if (cpu_has_amd_erratum(c, amd_erratum_400)) set_cpu_bug(c, X86_BUG_AMD_APIC_C1E); rdmsr_safe(MSR_AMD64_PATCH_LEVEL, &c->microcode, &dummy); @@ -878,22 +878,16 @@ static const int amd_erratum_400[] = static const int amd_erratum_383[] = AMD_OSVW_ERRATUM(3, AMD_MODEL_RANGE(0x10, 0, 0, 0xff, 0xf)); -static bool cpu_has_amd_erratum(const int *erratum) + +static bool cpu_has_amd_erratum(struct cpuinfo_x86 *cpu, const int *erratum) { - struct cpuinfo_x86 *cpu = __this_cpu_ptr(&cpu_info); int osvw_id = *erratum++; u32 range; u32 ms; - /* - * If called early enough that current_cpu_data hasn't been initialized - * yet, fall back to boot_cpu_data. - */ - if (cpu->x86 == 0) - cpu = &boot_cpu_data; - - if (cpu->x86_vendor != X86_VENDOR_AMD) - return false; + /* Should never be called on non-AMD-CPUs */ + if (WARN_ON(cpu->x86_vendor != X86_VENDOR_AMD)) + return false; if (osvw_id >= 0 && osvw_id < 65536 && cpu_has(cpu, X86_FEATURE_OSVW)) {
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