linux-kernel - Re: [PATCHv7 00/14] mm, x86/cc: Implement support for unaccepted memory

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Message-ID: <5af19000-4482-7eb9-f158-0a461891f087@intel.com>
Date:   Fri, 24 Jun 2022 09:57:14 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Peter Gonda <pgonda@...gle.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc:     Borislav Petkov <bp@...en8.de>, 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>,
        Mike Rapoport <rppt@...nel.org>,
        David Hildenbrand <david@...hat.com>,
        marcelo.cerri@...onical.com, tim.gardner@...onical.com,
        khalid.elmously@...onical.com, philip.cox@...onical.com,
        the arch/x86 maintainers <x86@...nel.org>,
        linux-mm@...ck.org, linux-coco@...ts.linux.dev,
        linux-efi@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv7 00/14] mm, x86/cc: Implement support for unaccepted
 memory

Peter, is your enter key broken?  You seem to be typing all your text in
a single unreadable paragraph.

On 6/24/22 09:37, Peter Gonda wrote:
> if a customer incorrectly labels their image it may fail to boot..

You're saying that firmware basically has two choices:
1. Accept all the memory up front and boot slowly, but reliably
2. Use thus "unaccepted memory" mechanism, boot fast, but risk that the
   VM loses a bunch of memory.

If the guest can't even boot because of a lack of memory, then the
pre-accepted chunk is probably too small in the first place.

If the customer screws up, they lose a bunch of the RAM they paid for.
That seems like a rather self-correcting problem to me.