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Date:   Mon, 5 Jun 2023 12:18:21 -0700
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Subject: Re: [PATCHv13 9/9] x86/tdx: Add unaccepted memory support
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To:     Tom Lendacky <thomas.lendacky@amd.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Borislav Petkov <bp@alien8.de>,
        Andy Lutomirski <luto@kernel.org>,
        Sean Christopherson <seanjc@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Joerg Roedel <jroedel@suse.de>,
        Ard Biesheuvel <ardb@kernel.org>
Cc:     Andi Kleen <ak@linux.intel.com>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@linux.intel.com>,
        David Rientjes <rientjes@google.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Ingo Molnar <mingo@redhat.com>,
        Dario Faggioli <dfaggioli@suse.com>,
        Mike Rapoport <rppt@kernel.org>,
        David Hildenbrand <david@redhat.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        marcelo.cerri@canonical.com, tim.gardner@canonical.com,
        khalid.elmously@canonical.com, philip.cox@canonical.com,
        aarcange@redhat.com, peterx@redhat.com, x86@kernel.org,
        linux-mm@kvack.org, linux-coco@lists.linux.dev,
        linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org
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 <1d24355c-3922-d5c7-4c05-f5ef0adaf5d2@amd.com>
From:   Dave Hansen <dave.hansen@intel.com>
In-Reply-To: <1d24355c-3922-d5c7-4c05-f5ef0adaf5d2@amd.com>
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On 6/2/23 07:26, Tom Lendacky wrote:
>> So this is a change in this version. If tdx_accept_memory() fails,
>> you'll report unknown platform. Wouldn't it be better to have an error
>> message that indicates a failure in the accept path?
>>
> 
> Maybe you can keep it similar to the v12 version with just a new error
> message, something like:
> 
>     if (early_is_tdx_guest()) {
>         if (!tdx_accept_memory(start, end))
>             error("TDX error accepting memory\n");
>     } else {
>         error("Cannot accept memory: unknown platform\n");
>     }

In the end, these errors aren't plumbed out to the page allocator.  They
*need* to succeed or we are dead anyway.  Should we just send a fatal
error up to the TDX module when we fail to accept memory?  It's
_slightly_ less opaque than plowing into an unaccepted page.