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

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Message-ID: <990d8c5c-1995-3ebf-e583-0e3f264ada0e@amd.com>
Date:   Tue, 19 Jul 2022 17:08:36 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Dave Hansen <dave.hansen@...el.com>, Borislav Petkov <bp@...en8.de>
Cc:     Ard Biesheuvel <ardb@...nel.org>,
        Dionna Amalie Glaze <dionnaglaze@...gle.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Peter Gonda <pgonda@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Sean Christopherson <seanjc@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Joerg Roedel <jroedel@...e.de>,
        Andi Kleen <ak@...ux.intel.com>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        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 <marcelo.cerri@...onical.com>,
        tim.gardner@...onical.com,
        Khalid ElMously <khalid.elmously@...onical.com>,
        philip.cox@...onical.com,
        the arch/x86 maintainers <x86@...nel.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        linux-coco@...ts.linux.dev, linux-efi <linux-efi@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "Yao, Jiewen" <jiewen.yao@...el.com>
Subject: Re: [PATCHv7 00/14] mm, x86/cc: Implement support for unaccepted
 memory

On 7/19/22 17:02, Dave Hansen wrote:
> On 7/19/22 14:50, Borislav Petkov wrote:
>> On Tue, Jul 19, 2022 at 02:35:45PM -0700, Dave Hansen wrote:
>>> They're trying to design something that can (forever) handle guests that
>>> might not be able to accept memory.
>> Wait, what?
>>
>> If you can't modify those guests to teach them to accept memory, how do
>> you add TDX or SNP guest support to them?
> 
> Mainline today, for instance, doesn't have unaccepted memory support for
> TDX or SEV-SNP guests.  But, they both still boot fine because folks
> either configure it on the host side not to *have* any unaccepted
> memory.  Or, they just live with the small (4GB??) amount of
> pre-accepted memory, which is fine for testing things.

Today, for SEV-SNP, OVMF accepts all of the memory in advance of booting 
the kernel.

Thanks,
Tom

>