linux-kernel - Re: [PATCHv4 3/8] efi/x86: Implement support for unaccepted memory

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Message-ID: <Yl8MRA6MxgNiLYv3@zn.tnic>
Date:   Tue, 19 Apr 2022 21:23:48 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     "Kirill A. Shutemov" <kirill@...temov.name>
Cc:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Sean Christopherson <seanjc@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Joerg Roedel <jroedel@...e.de>,
        Ard Biesheuvel <ardb@...nel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Tom Lendacky <thomas.lendacky@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Ingo Molnar <mingo@...hat.com>,
        Varad Gautam <varad.gautam@...e.com>,
        Dario Faggioli <dfaggioli@...e.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Mike Rapoport <rppt@...nel.org>,
        David Hildenbrand <david@...hat.com>, x86@...nel.org,
        linux-mm@...ck.org, linux-coco@...ts.linux.dev,
        linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv4 3/8] efi/x86: Implement support for unaccepted memory

On Tue, Apr 19, 2022 at 06:30:02PM +0300, Kirill A. Shutemov wrote:
> Hm. Dave was worried about having copies of _find_next_bit() and
> __bitmap_*() inside compressed/.

That's fine.

> How do we rectify code duplication and making decompresser self-contained?

Also fine - as long as the decompressor and kernel-proper are
independent.

> Do we care about multiple copies of the same code in the kernel?

The copied versions in the decompressor should be simply sufficient for
its use. And there shouldn't be that much of duplication.

Note that we're using the same strategy with perf tool - it does copy
kernel facilities when it needs them.

> Do we care about keeping them in sync?

Nope - as long as they're sufficient for the decompressor. My
expectation here is that the decompressor won't need too many
facilities.

Thx.

-- 
Regards/Gruss,
    Boris.

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