From 9f3a6cadf494f378b7839de14063793259ad5626 Mon Sep 17 00:00:00 2001 From: Jia Zhang Date: Tue, 23 Jan 2018 11:41:32 +0100 Subject: [PATCH] x86/microcode/intel: Extend BDW late-loading further with LLC size check commit 7e702d17ed138cf4ae7c00e8c00681ed464587c7 upstream. Commit b94b73733171 ("x86/microcode/intel: Extend BDW late-loading with a revision check") reduced the impact of erratum BDF90 for Broadwell model 79. The impact can be reduced further by checking the size of the last level cache portion per core. Tony: "The erratum says the problem only occurs on the large-cache SKUs. So we only need to avoid the update if we are on a big cache SKU that is also running old microcode." For more details, see erratum BDF90 in document #334165 (Intel Xeon Processor E7-8800/4800 v4 Product Family Specification Update) from September 2017. Fixes: b94b73733171 ("x86/microcode/intel: Extend BDW late-loading with a revision check") Signed-off-by: Jia Zhang Signed-off-by: Borislav Petkov Signed-off-by: Thomas Gleixner Acked-by: Tony Luck Link: https://lkml.kernel.org/r/1516321542-31161-1-git-send-email-zhang.jia@linux.alibaba.com Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/microcode/intel.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c index ac3e636ad586..f90f17610f62 100644 --- a/arch/x86/kernel/cpu/microcode/intel.c +++ b/arch/x86/kernel/cpu/microcode/intel.c @@ -40,6 +40,9 @@ #include #include +/* last level cache size per core */ +static int llc_size_per_core; + /* * Temporary microcode blobs pointers storage. We note here during early load * the pointers to microcode blobs we've got from whatever storage (detached @@ -1053,12 +1056,14 @@ static bool is_blacklisted(unsigned int cpu) /* * Late loading on model 79 with microcode revision less than 0x0b000021 - * may result in a system hang. This behavior is documented in item - * BDF90, #334165 (Intel Xeon Processor E7-8800/4800 v4 Product Family). + * and LLC size per core bigger than 2.5MB may result in a system hang. + * This behavior is documented in item BDF90, #334165 (Intel Xeon + * Processor E7-8800/4800 v4 Product Family). */ if (c->x86 == 6 && c->x86_model == INTEL_FAM6_BROADWELL_X && c->x86_mask == 0x01 && + llc_size_per_core > 2621440 && c->microcode < 0x0b000021) { pr_err_once("Erratum BDF90: late loading with revision < 0x0b000021 (0x%x) disabled.\n", c->microcode); pr_err_once("Please consider either early loading through initrd/built-in or a potential BIOS update.\n"); @@ -1125,6 +1130,15 @@ static struct microcode_ops microcode_intel_ops = { .microcode_fini_cpu = microcode_fini_cpu, }; +static int __init calc_llc_size_per_core(struct cpuinfo_x86 *c) +{ + u64 llc_size = c->x86_cache_size * 1024; + + do_div(llc_size, c->x86_max_cores); + + return (int)llc_size; +} + struct microcode_ops * __init init_intel_microcode(void) { struct cpuinfo_x86 *c = &boot_cpu_data; @@ -1135,6 +1149,8 @@ struct microcode_ops * __init init_intel_microcode(void) return NULL; } + llc_size_per_core = calc_llc_size_per_core(c); + return µcode_intel_ops; } -- 2.17.1