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Date:   Wed, 19 Jul 2023 10:31:06 +0800
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Subject: Re: [PATCH v9 1/2] x86/tdx: Retry TDVMCALL_MAP_GPA() when needed
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To:     Dexuan Cui <decui@microsoft.com>, ak@linux.intel.com,
        arnd@arndb.de, bp@alien8.de, brijesh.singh@amd.com,
        dan.j.williams@intel.com, dave.hansen@intel.com,
        dave.hansen@linux.intel.com, haiyangz@microsoft.com, hpa@zytor.com,
        jane.chu@oracle.com, kirill.shutemov@linux.intel.com,
        kys@microsoft.com, linux-arch@vger.kernel.org,
        linux-hyperv@vger.kernel.org, luto@kernel.org, mingo@redhat.com,
        peterz@infradead.org, rostedt@goodmis.org,
        sathyanarayanan.kuppuswamy@linux.intel.com, seanjc@google.com,
        tglx@linutronix.de, tony.luck@intel.com, wei.liu@kernel.org,
        x86@kernel.org, mikelley@microsoft.com
Cc:     linux-kernel@vger.kernel.org, Tianyu.Lan@microsoft.com,
        rick.p.edgecombe@intel.com
References: <20230621191317.4129-1-decui@microsoft.com>
 <20230621191317.4129-2-decui@microsoft.com>
From:   Xiaoyao Li <xiaoyao.li@intel.com>
In-Reply-To: <20230621191317.4129-2-decui@microsoft.com>
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On 6/22/2023 3:13 AM, Dexuan Cui wrote:
> GHCI spec for TDX 1.0 says that the MapGPA call may fail with the R10
> error code = TDG.VP.VMCALL_RETRY (1), and the guest must retry this
> operation for the pages in the region starting at the GPA specified
> in R11.
> 
> When a fully enlightened TDX guest runs on Hyper-V, Hyper-V can return
> the retry error when set_memory_decrypted() is called to decrypt up to
> 1GB of swiotlb bounce buffers.

just out of curiosity, what size does Hyper-v handle at most in one call?