linux-kernel - Re: [PATCH 1/2] x86/microcode/AMD: Load late on both threads too

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Message-ID: <12a12721-239b-457e-1ff7-f98c02cb7abe@intel.com>
Date:   Wed, 7 Jun 2023 13:15:42 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     X86 ML <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
        stable@...nel.org
Subject: Re: [PATCH 1/2] x86/microcode/AMD: Load late on both threads too

On 6/7/23 13:03, Borislav Petkov wrote:
> On Wed, Jun 07, 2023 at 12:36:53PM -0700, Dave Hansen wrote:
>> What's the benefit of doing the loading on both threads?  I would have
>> naively thought it was just wasted work.
> I have the perfect example for this, see:
> 
> e7ad18d1169c ("x86/microcode/AMD: Apply the patch early on every logical thread")
> 
> so it is for reasons like that.

Yikes, so the second CMT thread reports a bumped version but not all the
_effects_ of that version?  That's, uh ... fun???

>> I think I even have a back-burnered Intel patch around somewhere that
>> ensures that we *never* load on both threads.
> Interesting - I guess there are considerable differences in microcode
> architecture between the two. 😄

Yeah, sure seems that way.