Thanks for your comments. Happy new year! Jia
在 2018/1/2 上午6:10, Borislav Petkov 写道: > On Mon, Jan 01, 2018 at 10:04:47AM +0800, Jia Zhang wrote: >> Instead of blacklisting all types of Broadwell processor when running >> a late loading, only BDW-EP (signature 0x406f1, aka family 6, model 79, >> stepping 1) with the microcode version less than 0x0b000021 needs to >> be blacklisted. >> >> The erratum is documented in the the public documentation #334165 (See >> the item BDF90 for details). >> >> Signed-off-by: Jia Zhang <[email protected]> >> --- >> arch/x86/kernel/cpu/microcode/intel.c | 14 +++++++++++--- >> 1 file changed, 11 insertions(+), 3 deletions(-) > > Ok, I went and massaged your version, here's what I committed: > > --- > From: Jia Zhang <[email protected]> > Date: Mon, 1 Jan 2018 10:04:47 +0800 > Subject: [PATCH] x86/microcode/intel: Extend BDW late-loading with a revision > check > > Instead of blacklisting all model 79 CPUs when attempting a late > microcode loading, limit that only to CPUs with microcode revisions < > 0x0b000021 because only on those late loading may cause a system hang. > > For such processors either: > > a) a BIOS update which might contain a newer microcode revision > > or > > b) the early microcode loading method > > should be considered. > > Processors with revisions 0x0b000021 or higher will not experience such > hangs. > > For more details, see erratum BDF90 in document #334165 (Intel Xeon > Processor E7-8800/4800 v4 Product Family Specification Update) from > September 2017. > > Signed-off-by: Jia Zhang <[email protected]> > Acked-by: Tony Luck <[email protected]> > Cc: x86-ml <[email protected]> > Link: > http://lkml.kernel.org/r/[email protected] > [ Heavily massage commit message and pr_* statements. ] > Signed-off-by: Borislav Petkov <[email protected]> > --- > arch/x86/kernel/cpu/microcode/intel.c | 13 +++++++++++-- > 1 file changed, 11 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kernel/cpu/microcode/intel.c > b/arch/x86/kernel/cpu/microcode/intel.c > index 8ccdca6d3f9e..d9e460fc7a3b 100644 > --- a/arch/x86/kernel/cpu/microcode/intel.c > +++ b/arch/x86/kernel/cpu/microcode/intel.c > @@ -910,8 +910,17 @@ 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"); > + /* > + * 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). > + */ > + if (c->x86 == 6 && > + c->x86_model == INTEL_FAM6_BROADWELL_X && > + c->x86_mask == 0x01 && > + 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"); > return true; > } > >
