linux-kernel - Re: [PATCH Part2 v6 14/49] crypto: ccp: Handle the legacy TMR allocation when SNP is enabled

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Date:   Tue, 15 Nov 2022 15:26:38 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "Kalra, Ashish" <ashish.kalra@....com>
Cc:     vbabka@...e.cz, x86@...nel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, linux-coco@...ts.linux.dev,
        linux-mm@...ck.org, linux-crypto@...r.kernel.org,
        tglx@...utronix.de, mingo@...hat.com, jroedel@...e.de,
        thomas.lendacky@....com, hpa@...or.com, ardb@...nel.org,
        pbonzini@...hat.com, seanjc@...gle.com, vkuznets@...hat.com,
        jmattson@...gle.com, luto@...nel.org, dave.hansen@...ux.intel.com,
        slp@...hat.com, pgonda@...gle.com, peterz@...radead.org,
        srinivas.pandruvada@...ux.intel.com, rientjes@...gle.com,
        dovmurik@...ux.ibm.com, tobin@....com, michael.roth@....com,
        kirill@...temov.name, ak@...ux.intel.com, tony.luck@...el.com,
        marcorr@...gle.com, sathyanarayanan.kuppuswamy@...ux.intel.com,
        alpergun@...gle.com, dgilbert@...hat.com, jarkko@...nel.org,
        "Kaplan, David" <David.Kaplan@....com>
Subject: Re: [PATCH Part2 v6 14/49] crypto: ccp: Handle the legacy TMR
 allocation when SNP is enabled

On Mon, Nov 14, 2022 at 05:36:29PM -0600, Kalra, Ashish wrote:
> But there is still added complexity of handling hugepages as part of
> reclamation failures (both HugeTLB and transparent hugepages) and that

Why?

You want to offline pfns of 4K pages. What hugepages?

> means calling more static functions in mm/memory_failure.c
> 
> There is probably a more appropriate handler in mm/memory-failure.c:
> 
> soft_offline_page() - this will mark the page as HWPoisoned and also has
> handling for hugepages. And we can avoid adding a new page flag too.

So if some other code wants to dump the amount of all hwpoisoned pages,
it'll dump those too.

Don't you see what is wrong with this picture?

And btw, reusing the hwpoison flag

	PG_offlimits = PG_hwpoison

like previously suggested doesn't help here either.

IOW, I really don't like this lumping of semantics together. ;-\

-- 
Regards/Gruss,
    Boris.

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