Received-SPF: pass (google.com: domain of linux-crypto-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <9d8e5548-cb5e-ffd7-72e3-b65dbcf74938@amd.com>
Date:   Wed, 4 Jan 2023 11:30:14 +0530
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101
 Thunderbird/102.5.0
Subject: Re: [PATCH v2] crypto: ccp - Allocate TEE ring and cmd buffer using
 DMA APIs
To:     Herbert Xu <herbert@gondor.apana.org.au>
Cc:     Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        John Allen <john.allen@amd.com>,
        "David S . Miller" <davem@davemloft.net>,
        Sumit Semwal <sumit.semwal@linaro.org>,
        =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>,
        linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org,
        linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linaro-mm-sig@lists.linaro.org,
        Mythri PK <Mythri.Pandeshwarakrishna@amd.com>,
        Jeshwanth <JESHWANTHKUMAR.NK@amd.com>,
        Devaraj Rangasamy <Devaraj.Rangasamy@amd.com>,
        stable@vger.kernel.org, Jens Wiklander <jens.wiklander@linaro.org>
References: <651349f55060767a9a51316c966c1e5daa57a644.1670919979.git.Rijo-john.Thomas@amd.com>
 <20221215132917.GA11061@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net>
 <5771ea99-eef7-7321-dd67-4c42c0cbb721@amd.com>
 <Y66gTtjZf5ZT0lP0@gondor.apana.org.au>
Content-Language: en-US
From:   Rijo Thomas <Rijo-john.Thomas@amd.com>
In-Reply-To: <Y66gTtjZf5ZT0lP0@gondor.apana.org.au>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?ZjFtZHp4VDR2SWE5bjRaTXZjOXVUVGx2SmNIU3JNQVR4d1hpSWNpaHlEUXI0?=
 =?utf-8?B?QnEwWFNCeGRNVnpyN01PWW1EVW0vc1VmeEFQV1dmWVRMT25CRG9HR0dUL2RM?=
 =?utf-8?B?eDhKZXJIZDhTMnJ4b1JLa3NSekJ5ZGMzWGRxb05TdEZVVVc0YUZYNnFldGlp?=
 =?utf-8?B?M3BOY0FkbmFheFU2YjJER0lIRHBjRlJJNy9yMVNQd2JEWTN3VG1VTDRvYW52?=
 =?utf-8?B?Q2xTaUlEYU9aMVNGbXZOM3VlbUkxN3I2VjA2b3ZjTHM1SUpldmxxTVBXczc4?=
 =?utf-8?B?SXRnNmNHN1JJaHdlVTNQQkxxbDhmWjVaVjZqVS9sZDRROTNSWnIzdFlkWElz?=
 =?utf-8?B?ZzBjWUJmSTZsRnY1MVlHb0tlSFMwcGplOFI1TVF5ZjVCL2M2SDRDZGdSdks3?=
 =?utf-8?B?SnQxN1BBWFVZMTlVa1lYNkpMTDRJZHQzR2lxSEZHWU5sT2NwMU4rLy8yQW0x?=
 =?utf-8?B?ZDl2OVVmenUyYm4wQmtIcG5nY3NRZFNXeE43dXVVTk01WThjQ2dhNzMrM2tD?=
 =?utf-8?B?aFR4eDBvNCtYV1hCWi9pVW5NTWlwYlo0SFloS0RZZjhZOWxiMnQwVy90YVdH?=
 =?utf-8?B?S1VHU0VLTkUwVWozTmE3b3AyQ25YUWh0NTd2cklQN1FUNGNvWDZBcUFFQVNh?=
 =?utf-8?B?UzYrem9DMW1sY2ZIaDNVdlZ1MlFnazh5aXZ3VktHY3QxOTlDSkVnZ2llSFlE?=
 =?utf-8?B?RS9aTFBUekF4dHlzK2hWSXRXRm01NjdrSHQyUWJYTDh1Q2poTDRZVzhsOWZ0?=
 =?utf-8?B?MzBZMzdkL1FycHhnNWY4c3I4MUY3Uk1qMDh2RGFyQyt3WW13cy9iYkxiSHNq?=
 =?utf-8?B?Q20zN1ZaTFU3dEFmdTNjNTRSb3FBZFdWb3lMVjVMeDB0YXF5T1Z0dnoxTThs?=
 =?utf-8?B?ZFQyeE1nSXNWTnF3WHVkMFVxdnB1N2ZPNThzWmx1cVRMSHE0TXNFeDN3akxr?=
 =?utf-8?B?K28zVXpDaGhOWXBnaElNQTMvSkhnS1ZmVzJ4ekw3TjdnQXpPcGhuQmkvZFM3?=
 =?utf-8?B?ZTR2SFprNDNvd2lDREF4NXpUMCtIY2E0dnRUMkFTcHp2QXQ0S0Q4cjJxYUFh?=
 =?utf-8?B?SEdCSXZMb1JBTzBoVXBtTXpCODJDVFlSQ1lCbi93d1k3aVpNZ3c5cWttMDBa?=
 =?utf-8?B?WlhySnNWUFpGb0pCM1o1dHdqckdnMS92SEdXemwxRkp1by9LSU5JZlhsL1hp?=
 =?utf-8?B?OElmMlNQMENRTHNSa1JBR3pRdHI0YjhleVZiNVVxS1lwcWVNVjFOdWxmcTds?=
 =?utf-8?B?bUhlbHNrMGlKUlVjV3c5bDFFZmZzYjBkL2hwLzVVbUIyU0Q0cmZ5LzZnditT?=
 =?utf-8?B?WWJVSmRiTEthTUxTVk1DOVo3R2t2alBOZUxybU5BY2gvcW9Edm5VYTRpbldy?=
 =?utf-8?B?RXFhSnV0VG8vbXNnZ0g3b2lJeEVFZFduV3ZTVlZXbEVrRVFzZ3Z3K1B6Qjdv?=
 =?utf-8?B?MjFoRDIveTQvekl0MzRRVWpKcktsMGN4dW1zQS9ncU5FYTBlOWVWbThXVXEx?=
 =?utf-8?B?L04ycU5aRXA1Y2czVk82NG1wNStGZThHMThLVU1xcisxTVVlQXBtVktONll0?=
 =?utf-8?B?azRZS05xZHdDL3pUUHcxcy9BYVRra1VEdlBhZDNkTEFWNzRnSHZ0czRoRkVk?=
 =?utf-8?B?U1cyb1JFOXM1cG12QUVJU2hvK3h3amhybXM1VlFCalJVcTlCZzJuZjZIVy9Z?=
 =?utf-8?B?eGVNVDMwY2N6bm40M2VGRDcrRGphNlZEUEVqTnJxTUFXVWdwQU5iL0lXSFFk?=
 =?utf-8?B?R1J4blBsZVhpQ2w4Y1VlNzR0bjJyMVlaQmVGeS9BaDk4cUNHenpvZEZmdUto?=
 =?utf-8?B?Tkt3Z1l4RlMwb3JtZGMzQlVYdm5GdlNhcVcvQng3cGlMTWFaYmg3M2I3UHA3?=
 =?utf-8?B?QTllYkpkaUlQMjJiYWFndS9XQVhNK1Fud3ErTzdoNVlTWjRicFFJQ2g4QUhh?=
 =?utf-8?B?b2NTbE9UNE9vMDZaSGNLVGJMTXV1ZnlZNnIrQ08xL2l4ZkNmQzRYc2RrR1Fu?=
 =?utf-8?B?S2x5bXBsdzJKcDZsWnZkc1orajJsMnhHcWdOVCtFN2VnbGJWTjg2SFo1czJa?=
 =?utf-8?B?OFFNMzJUTkwzTjVvTDNXcmtXMGdkeUl5UTd1c3JDRkxGWXdQNlZMYlBhOEJ4?=
 =?utf-8?Q?I5q3t1iwHsxt9yRvvU3Ec0htZ?=
X-OriginatorOrg: amd.com
X-MS-Exchange-CrossTenant-Network-Message-Id: b086656b-d5ad-40f5-9667-08daee18fa34
X-MS-Exchange-CrossTenant-AuthSource: CH0PR12MB5346.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Jan 2023 06:00:27.4315
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: +V1TbRXLxm9puRt/WlLtCxFwa3NIk71uuOxRpppgBdgE+TLyWUXPgXkBP5AsGnUZkK32bCze8zjV+p+t/c/G/Q==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN9PR12MB5382
X-Spam-Status: No, score=-5.2 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NICE_REPLY_A,RCVD_IN_DNSWL_NONE,
        RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_PASS autolearn=ham
        autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-crypto.vger.kernel.org>
X-Mailing-List: linux-crypto@vger.kernel.org


On 12/30/2022 1:54 PM, Herbert Xu wrote:
> On Fri, Dec 23, 2022 at 05:45:24PM +0530, Rijo Thomas wrote:
>>
>>> dma_alloc_coherent memory is just as contiguous as __get_free_pages, and
>>> calling dma_alloc_coherent from a guest does not guarantee that the memory is
>>> contiguous in host memory either. The memory would look contiguous from the
>>> device point of view thanks to the IOMMU though (in both cases). So this is not
>>> about being contiguous but other properties that you might rely on (dma mask
>>> most likely, or coherent if you're not running this on x86?).
>>>
>>> Can you confirm why this fixes things and update the comment to reflect that.
>>
>> I see what you are saying.
>>
>> We verified this in Xen Dom0 PV guest, where dma_alloc_coherent() returned a memory
>> that is contiguous in machine address space, and the machine address was returned
>> in the dma handle (buf->dma).
> 
> So is this even relevant to the mainstream kernel or is this patch
> only needed for Xen Dom0?
> 
> Thanks,

Herbert,

This patch is no longer relevant to the mainstream kernel.

Thanks,
Rijo