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 <[email protected]>
> Cc: X86 ML <[email protected]>
> Cc: LKML <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Tony Luck <[email protected]>
> Cc: Andi Kleen <[email protected]>
> Cc: Boris Petkov <[email protected]>
> Cc: Tom Lendacky <[email protected]>
> Cc: Arjan Van De Ven <[email protected]>
>
> 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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