Messages in this thread | | | Date | Mon, 15 Jan 2018 09:48:51 -0200 | From | Henrique de Moraes Holschuh <> | Subject | Re: [PATCH 2/2] x86/microcode/intel: Extend BDW late-loading with platform id and LLC check |
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On Mon, 15 Jan 2018, Jia Zhang wrote: > For more details, see erratum BDF90 in document #334165 (Intel Xeon > Processor E7-8800/4800 v4 Product Family Specification Update) from > September 2017.
For the record, this erratum may well affect some E5v4 as well. Anything with a LLC/core ratio >= 2.5 is potentially affected as far as I could tell when I took a serious look at it months ago (based only on crash reports and public information).
It would be safer to just blacklist by sig == 0x406f1, revision < 0x0b00021, and LLC/core ratio >= 2.5, ignoring platform IDs.
> /* > * 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(c) > 2621440 && > + c->platform_id == 0xef && > 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");
The c->platform_id test looks wrong. The processor will only have a single bit set, it is the microcode update that has more than a single bit set.
And do you really want 0xef? That is everyhing the public available microcode updates can be applied to in the first place, so even a corrected test would be useless (it would always match) unless you actually expect to find never-seen-in-the-wild platform mask 0x10?
-- Henrique Holschuh
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