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Date:   Tue, 10 Aug 2021 07:08:58 -0700
From:   Dave Hansen <>
To:     "Kirill A. Shutemov" <>,
        Borislav Petkov <>,
        Andy Lutomirski <>,
        Sean Christopherson <>,
        Andrew Morton <>,
        Joerg Roedel <>
Cc:     Andi Kleen <>,
        Kuppuswamy Sathyanarayanan 
        David Rientjes <>,
        Vlastimil Babka <>,
        Tom Lendacky <>,
        Thomas Gleixner <>,
        Peter Zijlstra <>,
        Paolo Bonzini <>,
        Ingo Molnar <>,
        Varad Gautam <>,
        Dario Faggioli <>,,,,,
        "Kirill A. Shutemov" <>
Subject: Re: [PATCH 0/5] x86: Impplement support for unaccepted memory

On 8/9/21 11:26 PM, Kirill A. Shutemov wrote:
> UEFI Specification version 2.9 introduces concept of memory acceptance:
> Some Virtual Machine platforms, such as Intel TDX or AMD SEV-SNP,
> requiring memory to be accepted before it can be used by the guest.
> Accepting happens via a protocol specific for the Virtrual Machine
> platform.
> Accepting memory is costly and it makes VMM allocate memory for the
> accepted guest physical address range. We don't want to accept all memory
> upfront.

This could use a bit more explanation.  Any VM is likely to *eventually*
touch all its memory, so it's not like a VMM has a long-term advantage
by delaying this.

So, it must have to do with resource use at boot.  Is this to help boot

I had expected this series, but I also expected it to be connected to
CONFIG_DEFERRED_STRUCT_PAGE_INIT somehow.  Could you explain a bit how
this problem is different and demands a totally orthogonal solution?

For instance, what prevents us from declaring: "Memory is accepted at
the time that its 'struct page' is initialized" ?  Then, we use all the
infrastructure we already have for DEFERRED_STRUCT_PAGE_INIT.

This series isn't too onerous, but I do want to make sure that we're not
reinventing the wheel.

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