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From:   Marc Orr <marcorr@google.com>
Date:   Fri, 24 Jun 2022 10:19:07 -0700
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Subject: Re: [PATCHv7 00/14] mm, x86/cc: Implement support for unaccepted memory
To:     Dave Hansen <dave.hansen@intel.com>
Cc:     Peter Gonda <pgonda@google.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Borislav Petkov <bp@alien8.de>,
        Andy Lutomirski <luto@kernel.org>,
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        Andrew Morton <akpm@linux-foundation.org>,
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        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@linux.intel.com>,
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        Vlastimil Babka <vbabka@suse.cz>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Thomas Gleixner <tglx@linutronix.de>,
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On Fri, Jun 24, 2022 at 10:10 AM Dave Hansen <dave.hansen@intel.com> wrote:
>
> On 6/24/22 10:06, Marc Orr wrote:
> > I think Peter's point is a little more nuanced than that. Once lazy
> > accept goes into the guest firmware -- without the feature negotiation
> > that Peter is suggesting -- cloud providers now have a bookkeeping
> > problem. Which images have kernels that can boot from a guest firmware
> > that doesn't pre-validate all the guest memory?
>
> Hold on a sec though...
>
> Is this a matter of
>
>         can boot from a guest firmware that doesn't pre-validate all the
>         guest memory?
>
> or
>
>         can boot from a guest firmware that doesn't pre-validate all the
>         guest memory ... with access to all of that guest's RAM?
>
> In other words, are we talking about "fails to boot" or "can't see all
> the RAM"?

Ah... yeah, you're right, Dave -- I guess it's the latter. The guest
won't have access to all of the memory that the customer is paying
for. But that's still bad. If the customer buys a 96 GB VM and can
only see 4GB because they're kernel doesn't have these patches they're
going to be confused and frustrated.