On Sun, 2018-01-21 at 15:31 +0100, Thomas Gleixner wrote: > > > > XX: Do we want a microcode blacklist? > > Oh yes, we want a microcode blacklist. Ideally we refuse to load the > affected microcode in the first place and if its already loaded then at > least avoid to use the borked features. > > PR texts promising that Intel is committed to transparency in this matter > are not sufficient. Intel, please provide the facts, i.e. a proper list of > micro codes and affected SKUs, ASAP. They've finally published one, at https://newsroom.intel.com/wp-content/uploads/sites/11/2018/01/microcode-update-guidance.pdf For shits and giggles, you can compare it with the one at https://kb.vmware.com/s/article/52345 Intel's seems to be a bit rushed. For example for Broadwell-EX 406F1 they say "0x25, 0x23" are bad, but VMware's list says 0x0B000025 and I have a CPU with 0x0B0000xx. So I've "corrected" their numbers in attempt at a blacklist patch accordingly, and likewise for some Skylake SKUs. But there are others in Intel's list that I can't easily proofread for them right now. Am I missing something? diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index b720dacac051..52855d1a4f9a 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -102,6 +102,57 @@ static void probe_xeon_phi_r3mwait(struct cpuinfo_x86 *c) ELF_HWCAP2 |= HWCAP2_RING3MWAIT; } +/* + * Early microcode releases for the Spectre v2 mitigation were broken: + * https://newsroom.intel.com/wp-content/uploads/sites/11/2018/01/microcode-update-guidance.pdf + * VMware also has a list at https://kb.vmware.com/s/article/52345 + */ +struct sku_microcode { + u8 model; + u8 stepping; + u32 microcode; +}; +static const struct sku_microcode spectre_bad_microcodes[] = { + { INTEL_FAM6_KABYLAKE_DESKTOP, 0x0B, 0x80 }, + { INTEL_FAM6_KABYLAKE_MOBILE, 0x0A, 0x80 }, + { INTEL_FAM6_KABYLAKE_MOBILE, 0x0A, 0x80 }, + { INTEL_FAM6_KABYLAKE_MOBILE, 0x09, 0x80 }, + { INTEL_FAM6_KABYLAKE_DESKTOP, 0x09, 0x80 }, + { INTEL_FAM6_SKYLAKE_X, 0x04, 0x0200003C }, + { INTEL_FAM6_SKYLAKE_MOBILE, 0x03, 0x000000C2 }, + { INTEL_FAM6_SKYLAKE_DESKTOP, 0x03, 0x000000C2 }, + { INTEL_FAM6_BROADWELL_CORE, 0x04, 0x28 }, + { INTEL_FAM6_BROADWELL_GT3E, 0x01, 0x0000001B }, + { INTEL_FAM6_HASWELL_ULT, 0x01, 0x21 }, + { INTEL_FAM6_HASWELL_GT3E, 0x01, 0x18 }, + { INTEL_FAM6_HASWELL_CORE, 0x03, 0x23 }, + { INTEL_FAM6_IVYBRIDGE_X, 0x04, 0x42a }, + { INTEL_FAM6_HASWELL_X, 0x02, 0x3b }, + { INTEL_FAM6_HASWELL_X, 0x04, 0x10 }, + { INTEL_FAM6_HASWELL_CORE, 0x03, 0x23 }, + { INTEL_FAM6_BROADWELL_XEON_D, 0x02, 0x14 }, + { INTEL_FAM6_BROADWELL_XEON_D, 0x03, 0x7000011 }, + { INTEL_FAM6_BROADWELL_GT3E, 0x01, 0x0000001B }, + /* For 406F1 Intel says "0x25, 0x23" while VMware says 0x0B000025 + * and a real CPU has a firmware in the 0x0B0000xx range. So: */ + { INTEL_FAM6_BROADWELL_X, 0x01, 0x0b000025 }, + { INTEL_FAM6_KABYLAKE_DESKTOP, 0x09, 0x80 }, + { INTEL_FAM6_SKYLAKE_X, 0x03, 0x100013e }, + { INTEL_FAM6_SKYLAKE_X, 0x04, 0x200003c }, +}; + +static int bad_spectre_microcode(struct cpuinfo_x86 *c) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(spectre_bad_microcodes); i++) { + if (c->x86_model == spectre_bad_microcodes[i].model && + c->x86_mask == spectre_bad_microcodes[i].stepping) + return (c->microcode <= spectre_bad_microcodes[i].microcode); + } + return 0; +} + static void early_init_intel(struct cpuinfo_x86 *c) { u64 misc_enable; @@ -122,6 +173,18 @@ static void early_init_intel(struct cpuinfo_x86 *c) if (c->x86 >= 6 && !cpu_has(c, X86_FEATURE_IA64)) c->microcode = intel_get_microcode_revision(); + if ((cpu_has(c, X86_FEATURE_SPEC_CTRL) || + cpu_has(c, X86_FEATURE_AMD_SPEC_CTRL) || + cpu_has(c, X86_FEATURE_AMD_PRED_CMD) || + cpu_has(c, X86_FEATURE_AMD_STIBP)) && bad_spectre_microcode(c)) { + pr_warn("Intel Spectre v2 broken microcode detected; disabling SPEC_CTRL\n"); + clear_cpu_cap(c, X86_FEATURE_SPEC_CTRL); + clear_cpu_cap(c, X86_FEATURE_STIBP); + clear_cpu_cap(c, X86_FEATURE_AMD_SPEC_CTRL); + clear_cpu_cap(c, X86_FEATURE_AMD_PRED_CMD); + clear_cpu_cap(c, X86_FEATURE_AMD_STIBP); + } + /* * Atom erratum AAE44/AAF40/AAG38/AAH41: *
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