Messages in this thread | | | Date | Thu, 22 Feb 2018 12:00:57 +0100 | From | Borislav Petkov <> | Subject | Re: [v2 1/3] x86/microcode/intel: Check microcode revision before updating sibling threads |
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On Wed, Feb 21, 2018 at 10:33:23PM -0800, Ashok Raj wrote: > After updating microcode on one of the threads in the core, the > thread sibling automatically gets the update since the microcode > resources are shared. Check the ucode revision on the CPU before > performing a ucode update. > > Signed-off-by: Ashok Raj <ashok.raj@intel.com> > Cc: X86 ML <x86@kernel.org> > Cc: LKML <linux-kernel@vger.kernel.org> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Ingo Molnar <mingo@kernel.org> > Cc: Tony Luck <tony.luck@intel.com> > Cc: Andi Kleen <andi.kleen@intel.com> > Cc: Boris Petkov <bp@suse.de> > Cc: Tom Lendacky <thomas.lendacky@amd.com> > Cc: Arjan Van De Ven <arjan.van.de.ven@intel.com> > > Updates: > v2: Address Boris's to cleanup apply_microcode_intel > v3: Fixups per Ingo: Spell Checks
That changelog...
> ---
... comes under this line so that it can be ignored by tools.
> arch/x86/kernel/cpu/microcode/intel.c | 28 +++++++++++++++++++++++++--- > 1 file changed, 25 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c > index 09b95a7..137c9f5 100644 > --- a/arch/x86/kernel/cpu/microcode/intel.c > +++ b/arch/x86/kernel/cpu/microcode/intel.c > @@ -589,6 +589,18 @@ static int apply_microcode_early(struct ucode_cpu_info *uci, bool early) > if (!mc) > return 0; > > + rev = intel_get_microcode_revision();
Ok, so I'm still wondering what this patch is trying to achieve.
intel_get_microcode_revision() does already *two* MSR reads and a CPUID. So it is not speed improvements - it actually makes loading slower due to that checking.
So why are we doing this again?
-- Regards/Gruss, Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --
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