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....@intel.com>
> Cc: X86 ML <x...@kernel.org>
> Cc: LKML <linux-kernel@vger.kernel.org>
> Cc: Thomas Gleixner <t...@linutronix.de>
> Cc: Ingo Molnar <mi...@kernel.org>
> Cc: Tony Luck <tony.l...@intel.com>
> Cc: Andi Kleen <andi.kl...@intel.com>
> Cc: Boris Petkov <b...@suse.de>
> Cc: Tom Lendacky <thomas.lenda...@amd.com>
> Cc: Arjan Van De Ven <arjan.van.de....@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 Imend├Ârffer, Jane Smithard, Graham Norton, HRB 21284 
(AG N├╝rnberg)
-- 

Reply via email to