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Date:   Thu, 21 Jul 2022 09:49:03 -0700
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Subject: Re: [PATCH v8 5/5] x86/tdx: Add Quote generation support
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To:     Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@linux.intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org
Cc:     "H . Peter Anvin" <hpa@zytor.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Tony Luck <tony.luck@intel.com>,
        Andi Kleen <ak@linux.intel.com>,
        Kai Huang <kai.huang@intel.com>,
        Wander Lairson Costa <wander@redhat.com>,
        Isaku Yamahata <isaku.yamahata@gmail.com>,
        marcelo.cerri@canonical.com, tim.gardner@canonical.com,
        khalid.elmously@canonical.com, philip.cox@canonical.com,
        linux-kernel@vger.kernel.org
References: <20220609025220.2615197-1-sathyanarayanan.kuppuswamy@linux.intel.com>
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 <d3808510-9974-258e-0c7b-9a76e0868d48@intel.com>
 <f043d9f5-8f89-4ef3-2ce1-75665122bb3a@linux.intel.com>
From:   Dave Hansen <dave.hansen@intel.com>
In-Reply-To: <f043d9f5-8f89-4ef3-2ce1-75665122bb3a@linux.intel.com>
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On 7/21/22 09:42, Sathyanarayanan Kuppuswamy wrote:
> On 7/21/22 9:08 AM, Dave Hansen wrote:
>> On 6/8/22 19:52, Kuppuswamy Sathyanarayanan wrote:
>>> For shared buffer allocation, alternatives like using the DMA API is
>>> also considered. Although it simpler to use, it is not preferred because
>>> dma_alloc_*() APIs require a valid bus device as argument, which would
>>> need converting the attestation driver into a platform device driver.
>>> This is unnecessary, and since the attestation driver does not do real
>>> DMA, there is no need to use real DMA APIs.
>> Let's actually try to walk through the requirements for the memory
>> allocation here.
>>
>>  1. The guest kernel needs to allocate some guest physical memory
>>     for the attestation data buffer
> Physically contiguous memory.

Remind me how large the quote structures are.