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Date: Thu, 28 Jul 2022 15:17:49 +0800 From: Huang Rui To: Igor Mammedov Cc: "anthony.perard@citrix.com" , "qemu-devel@nongnu.org" , "xen-devel@lists.xenproject.org" , "Huang, Trigger" Subject: Re: Question to mem-path support at QEMU for Xen Message-ID: References: <20220727101930.66ed56e1@redhat.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220727101930.66ed56e1@redhat.com> X-ClientProxiedBy: SI2PR01CA0050.apcprd01.prod.exchangelabs.com (2603:1096:4:193::21) To DM5PR12MB2504.namprd12.prod.outlook.com (2603:10b6:4:b5::19) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 75e122b7-116b-49ec-db96-08da70695505 X-MS-TrafficTypeDiagnostic: MN2PR12MB3935:EE_ X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: JxxMHokLlN3zmJXA13qIHOsvsOEYi1KXj1IEya4deqizHbsGO883Fu+10crgMg7B/ECRrQyVYZsME2z6Y4BURkiqhiV+XobV1xiXJkYNGlxfnwh2i2KeTlOUtoLn1aVjItidZBvZIYd1+eW/Hj/aTGwCJVbx3Em9svxRZHpcQI1O5V1K0AMaCYmjPdoHGS2qTKAwcHUbyXOg4mxAJYWfS0dVTN9a7i4gMjM0mgfqL7E9mP1rjJMj3K+iKdKUbqSHlBNG57nfMAsE4TevopFLfLdE0Cf16+YDKYZGm6vZQNsevT0zg744SXLCx4tODNlqFop4E88ZPrIWrPws2ht54WW3fvg3uX4n+RXwCbZQbXoCD/voXGhMLzrun+hr5jAy9sUMJInuv+Z3UpH36TqYHLcpEysN/godpo3wR33eW87Mv3tnKckTIYHzXq4543CUMK1o24NA0NV5EYe92c1PLzBuouUj6ye18iLKSaEmnjBfX/ob/Rj0IxPLmgtMiZ/HHsk8Fa/wP8sOkxVuL0jD6JNdgrrahQSdpcpXT0V7aQYvsGKV3pwZSrha9o2hm5rRKj3EaFBMn8eMEt0x93Hn+KAg2JWHf1YWfq8dA9jQ4cw51gThVqwwbjXk42ke65SHEKYJ1p9WU346uJGuAwXX8+DETLJovOvm2F+LVAfRb9KXKeBXJRF/yaJQEahc1yksz0ycQ3UcwTP/IGlUiPSWwdHPp19U//N7s/oZSxB6zonR5B1ozqwuF4xZs1/K9ijl X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DM5PR12MB2504.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230016)(4636009)(346002)(376002)(136003)(39860400002)(366004)(396003)(41300700001)(26005)(36756003)(6512007)(6666004)(6506007)(8676002)(6486002)(478600001)(66946007)(66556008)(66476007)(38100700002)(4326008)(83380400001)(8936002)(5660300002)(2616005)(54906003)(86362001)(316002)(186003)(2906002)(6916009);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?KEqfQ6Vifx4G6sz3S7Q7Lbs5N2ZlBkepJtyHnl6GmiBj5npSNUo8IvuesaLp?= =?us-ascii?Q?J8yj9shP7NdDO/sI8Rj4bl8pIyNFa7Eo/G2qURKswDHWwZex63Mr5GrbS+kV?= =?us-ascii?Q?2PZ/Fri5dmfn8M3pSwaocw8eHXPQdqNk2Gtf56xjnxXW35xKtDmh8JiavHdV?= =?us-ascii?Q?WqMiQ0ioN9NgYU8o9I21+xKbribsyWBRtQhXo62qolCPQCjmj0uiAazEUNsZ?= =?us-ascii?Q?ZSMn3Jf1A0jGGGW2lqYGHd4UzMe1agbLny4HvYU/UvRbTIgyAV0GDNFudaJd?= =?us-ascii?Q?34mquZzvKSJ05xLl1N7rpQAIXn7aiSxMWSUP/E7/l1nWcPZkItzBzvCARmvD?= =?us-ascii?Q?T8oN4YnVYVK2ULc36HsAtcTVGkM/HPoWMF4B+AsKVOczHw+vWFd+EeVgj1s7?= =?us-ascii?Q?wREN/d++dUCILX4yv1L6ft6ixGAnRFagmnwBpQ3cFj+LVi/lBoW2cbWGWbLC?= =?us-ascii?Q?UvKc9feEmoqu9C0m7fEwF2hZDQnsbQ3OiCjeJnI3/5pW5gKJLwXoEFxCn+xg?= =?us-ascii?Q?BpfSufYiZPQIYs57/nlm3oN/xyO58LQEltpHHL0xjJf4XH+Eb4FKKlDrztpz?= =?us-ascii?Q?5yXDt9+kYbQYRM+ppW5FljAenWz5Bu/BZRT44JZRlIlGXRuBz/a26UL4C3No?= =?us-ascii?Q?nqd8Ehvd5BmWN4aV53OsKnAKvvXHhBRtFyvUkdV3taev2Xbsvx06QgkURzA9?= =?us-ascii?Q?Slg0riC2npx73Sv8ztbrwsIs4oYjbsW8v76NXU5bdflAz8px4cpZTWRzAPsQ?= =?us-ascii?Q?W1ilqZgnWvmGRroRReDDgqvxS2kOL7vbHzFIHsCWNQBGhzlo518owAi+XqYj?= =?us-ascii?Q?GTh6wjPUTA4ycM6M7KWBOHbMbnOAwaCL31qfNE1lDiFjEL9VHbiSkY62A87c?= =?us-ascii?Q?+cqfWv9v0UB1tOBezTC3Gdg0TorlIMFimCoeXxbjp499Fs0eNaotj9NPUtdy?= =?us-ascii?Q?10sR2Zf1ubhdq0WTQPNebVfSVw4HYTcdNJatvG3hWxRYxu8n1iOr4kGXFBvv?= =?us-ascii?Q?GhDFVWyV28dw479ICxj/4fdj7G+r5ph5s6dIhSZra1sky0V/H+ksADR6rmEh?= =?us-ascii?Q?JdhjUL5/ymJjUU49gHQbcyV13V0gVNOmo3bE3euI9tiOyrFpZYn0qG0oXHQI?= =?us-ascii?Q?JRZUay/NThRmfBglkPBqUK9qBIl4e/sk8un11emMv9hPgPtDI5/k8NvZg9X5?= =?us-ascii?Q?GIg9oBEMy5duK7XvuBHYiA/afWBNwD2NTzOKCxImJoB4mM+nH9x42qqLUSpP?= =?us-ascii?Q?t18dfdVIAGr2G6YXQmDrd/joGFZgbAuDyPVrILQil8a6DFNFW/TZ9kQE8a59?= =?us-ascii?Q?ejtH8eG+y1JAv7c60VxFTLbZaan42fIrQ4Ht+3xsgDcPBsz75Esp7CN3+bMr?= =?us-ascii?Q?mmAopwKXQU9hmUgQutn8P5U1PKMKwGyPHUbODSYSGBf1NtoMFTVQ7yP+r4KO?= =?us-ascii?Q?eLJWmCRRNssyLxEsUSbLw/nIX31PfpzP80OxxQIjN7dXR5+eWA7QaPUHUxrN?= =?us-ascii?Q?eu+pzXiNNIjERS1d4KFI0EBMZG6CYo/gqQ+6tU9iA6iMdB6+NK9m9D4FbDUU?= =?us-ascii?Q?nMAMupKfPPknKb7P3Mawa2yiW4EF2o15pJRbuuYX?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: 75e122b7-116b-49ec-db96-08da70695505 X-MS-Exchange-CrossTenant-AuthSource: DM5PR12MB2504.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Jul 2022 07:18:12.8076 (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: AUHjGMhFxkTB/QGy2WCt9r2AHbSwJxuWmEL68dCbBB84dTGSP/1X9g/AQp32xQLR58U5Z6kvzT8dlaDIASNA5A== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB3935 Hi Igor, Appreciate you for the reply! On Wed, Jul 27, 2022 at 04:19:30PM +0800, Igor Mammedov wrote: > On Tue, 26 Jul 2022 15:27:07 +0800 > Huang Rui wrote: > > > Hi Anthony and other Qemu/Xen guys, > > > > We are trying to enable venus on Xen virtualization platform. And we would > > like to use the backend memory with memory-backend-memfd,id=mem1,size=4G > > options on QEMU, however, the QEMU will tell us the "-mem-path" is not > > supported with Xen. I verified the same function on KVM. > > > > qemu-system-i386: -mem-path not supported with Xen > > > > So may I know whether Xen has any limitation that support > > memory-backend-memfd in QEMU or just implementation is not done yet? > > Currently Xen doesn't use guest RAM allocation the way the rest of > accelerators do. (it has hacks in memory_region/ramblock API, > that divert RAM allocation calls to Xen specific API) I am new for Xen and QEMU, we are working on GPU. We would like to have a piece of backend memroy like video memory for VirtIO GPU to support guest VM Mesa Vulkan (Venus). Do you mean we can the memory_region/ramblock APIs to work around it? > > The sane way would extend Xen to accept RAM regions (whatever they are > ram or fd based) QEMU allocates instead of going its own way. This way > it could reuse all memory backends that QEMU provides for the rest of > the non-Xen world. (not to mention that we could drop non trivial > Xen hacks so that guest RAM handling would be consistent with other > accelerators) > May I know what do you mean by "going its own way"? This sounds good, could you please elaborate on how can we implement this? We would like to give a try to address the problem on Xen. Would you mind to point somewhere that I can learn and understand the RAM region. Very happy to see your suggestions! Thanks & Best Regards, Ray