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Message-ID: <20171226105144.okolo6shqjghrr7j@pd.tnic> Date: Tue, 26 Dec 2017 11:51:44 +0100 From: Borislav Petkov <bp@...en8.de> To: Jia Zhang <qianyue.zj@...baba-inc.com> Cc: tglx@...utronix.de, mingo@...hat.com, hpa@...or.com, x86@...nel.org, linux-kernel@...r.kernel.org, tony.luck@...el.com Subject: Re: [PATCH v3] x86/microcode/intel: Blacklist the specific BDW-EP for late loading On Tue, Dec 26, 2017 at 09:44:31AM +0800, Jia Zhang wrote: > Instead of blacklisting all Broadwell processorsi for running a late ^^^^^^^^^^^ Please run all text in this patch through a spellchecker. > loading, only BDW-EP (signature 406f1) with the microcode version Please write out what that signature actually is - it might be confusing to people not dealing with family/model/stepping on a daily basis. > less than 0x0b000021 needs to be blacklisted. > > This is documented in the the public documentation #334165 (See the > item BDF90 for details). > > Signed-off-by: Jia Zhang <qianyue.zj@...baba-inc.com> > --- > arch/x86/kernel/cpu/microcode/intel.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c > index 8ccdca6..d2c1638 100644 > --- a/arch/x86/kernel/cpu/microcode/intel.c > +++ b/arch/x86/kernel/cpu/microcode/intel.c > @@ -910,8 +910,15 @@ static bool is_blacklisted(unsigned int cpu) > { > struct cpuinfo_x86 *c = &cpu_data(cpu); > > - if (c->x86 == 6 && c->x86_model == INTEL_FAM6_BROADWELL_X) { > - pr_err_once("late loading on model 79 is disabled.\n"); > + /* > + * The Broadwell-EP processor with the microcode version less > + * then 0x0b000021 may reault in system hang when running a late ^^^^^^ typo. > + * loading. 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 && c->microcode < 0x0b000021U) { ^ The appended 'U' is for? I mean, I'd expect the implicit promotion rules to kick in here as always. :-) > + pr_err_once("late loading on model 79 (sig 64f1) is disabled.\n"); See, you can get the sig wrong yourself too. Or were you trying to write family/model/stepping in some short form? Also, this error message needs to explain exactly why late loading is disabled - because microcode revision is < 0x0b000021. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.
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