linux-kernel - Re: [PATCH v3 08/10] x86/mtrr: let cache_aps_delayed_init replace mtrr_aps_delayed

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Message-ID: <YzbZJEeVHkTnWIfc@zn.tnic>
Date:   Fri, 30 Sep 2022 13:55:16 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Juergen Gross <jgross@...e.com>
Cc:     xen-devel@...ts.xenproject.org, x86@...nel.org,
        linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH v3 08/10] x86/mtrr: let cache_aps_delayed_init replace
 mtrr_aps_delayed_init

On Thu, Sep 29, 2022 at 10:26:59AM +0200, Juergen Gross wrote:
> So right now I'm inclined to be better on the safe side by not adding any
> cpu hotplug hook, but to use just the same "delayed AP init" flag as today,
> just renaming it. This would leave the delayed MTRR/PAT init in place for
> resume and kexec cases, but deferring the MTRR/PAT cleanup due to this
> potential issue seems not appropriate, as the cleanup isn't changing the
> behavior here.

Ok, what's wrong with adding a special hotplug level just for that thing
and running it very early? Practically pretty much where it was in time,
in identify_secondary_cpu()?

Having a special one is warranted, as you explain, I'd say.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette