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Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Shuah Khan , Mike Rapoport , Steven Price , "Maciej S . Szmigiero" , Vlastimil Babka , Vishal Annapurve , Yu Zhang , "Kirill A . Shutemov" , luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com, david@redhat.com, aarcange@redhat.com, ddutile@redhat.com, dhildenb@redhat.com, Quentin Perret , Michael Roth , mhocko@suse.com, Muchun Song References: <20220706082016.2603916-1-chao.p.peng@linux.intel.com> <20220706082016.2603916-5-chao.p.peng@linux.intel.com> <20220713074458.GB2831541@chaop.bj.intel.com> <74097857-1908-2ff2-1e54-bf7e658ea6c6@amd.com> <20220713234903.GA2881285@chaop.bj.intel.com> From: "Gupta, Pankaj" In-Reply-To: <20220713234903.GA2881285@chaop.bj.intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: AM6PR08CA0031.eurprd08.prod.outlook.com (2603:10a6:20b:c0::19) To CY4PR1201MB0181.namprd12.prod.outlook.com (2603:10b6:910:1f::11) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 9b7e9975-1e2b-4172-a6e8-08da654f81b1 X-MS-TrafficTypeDiagnostic: DM5PR1201MB0220:EE_ X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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>>>>> + struct shmem_inode_info *info = SHMEM_I(inode); >>>>> + >>>>> + if (info->memfile_node.flags & MEMFILE_F_UNMOVABLE) >>>>> + return -EOPNOTSUPP; >>>>> + return migrate_page(mapping, newpage, page, mode); >>>> >>>> Wondering how well page migrate would work for private pages >>>> on shmem memfd based backend? >>> >>> From high level: >>> - KVM unset MEMFILE_F_UNMOVABLE bit to indicate it capable of >>> migrating a page. >>> - Introduce new 'migrate' callback(s) to memfile_notifier_ops for KVM >>> to register. >>> - The callback is hooked to migrate_page() here. >>> - Once page migration requested, shmem calls into the 'migrate' >>> callback(s) to perform additional steps for encrypted memory (For >>> TDX we will call TDH.MEM.PAGE.RELOCATE). >> >> Yes, that would require additional (protocol specific) handling for private >> pages. Was trying to find where "MEMFILE_F_UNMOVABLE" flag is set currently? > > It's set with memfile_register_notifier() in patch 13. o.k. Thanks, Pankaj