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Shutemov" Subject: Re: [RFC PATCH v12 14/33] KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-specific backing memory Message-ID: Reply-To: Yan Zhao References: <20230914015531.1419405-1-seanjc@google.com> <20230914015531.1419405-15-seanjc@google.com> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20230914015531.1419405-15-seanjc@google.com> X-ClientProxiedBy: SI2PR01CA0045.apcprd01.prod.exchangelabs.com (2603:1096:4:193::19) To DS7PR11MB5966.namprd11.prod.outlook.com (2603:10b6:8:71::6) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS7PR11MB5966:EE_|DS0PR11MB7579:EE_ X-MS-Office365-Filtering-Correlation-Id: d124c74f-f70b-4ed2-14b3-08dbb5b67e12 X-LD-Processed: 46c98d88-e344-4ed4-8496-4ed7712e255d,ExtAddr X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: NIw6hxPN7hhBAwhQDNNnvuWA0tTTlfsknANlXPjN1o5gOZqRlV8YdrIyZzqH8NN9levkV850Cj54z6tqYwGRz9SYmOBv/GUkHELzzppgdRb60ClSk3OmoidRr3buiJ51DR7cVXChrnGs7qn0IGggHWMFF0jEwjhGRISwslLCqGIEYe2+E9UopaazZr34Cp55W/V4nH4iWX87lAXo6D9nvbA/WSwSf4IGgZSrG4o+UmkW6sYzdgJ2O1SYVE3ms4Z9hJGvPwH2CoOJaiRKMVubtPkpe7YUrWpQiVsIOnRcfpglRVPR3/XsCy2z9WFY1R3AxFUjNXrAi2+mYeDAQa1oG2qf0p5klAd+vkAdy8O/Sf0vy1UYwoWAtyq5kP4RN3951pvKEJ6fWfFsda6yxgXBNqYeeX0uxcAPDjGVGzydTfFRpN4BXfNee1s3mlnKxz3Z2th7Q52nWOMIpP4Oybcnw26yn3eLNfuRq5jFMCCfRPMXAmVYd2TqXWTRt54Xs/YQCOd2irtRctHrdII+IPni9toZq83BHsXwAvvm7E23Dn3/RW5zk9Dm391WIx0kRt4Z X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DS7PR11MB5966.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230031)(346002)(366004)(39860400002)(396003)(136003)(376002)(186009)(451199024)(1800799009)(7416002)(66556008)(7406005)(3450700001)(5660300002)(83380400001)(82960400001)(38100700002)(4326008)(8676002)(86362001)(8936002)(2906002)(54906003)(41300700001)(6916009)(316002)(66476007)(66946007)(6512007)(6506007)(6666004)(26005)(6486002)(478600001);DIR:OUT;SFP:1102; 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> + > + /* TODO: Support huge pages. */ > + folio = filemap_grab_folio(file->f_mapping, index); > + if (IS_ERR_OR_NULL(folio)) > + return NULL; > + > + /* > + * Use the up-to-date flag to track whether or not the memory has been > + * zeroed before being handed off to the guest. There is no backing > + * storage for the memory, so the folio will remain up-to-date until > + * it's removed. > + * > + * TODO: Skip clearing pages when trusted firmware will do it when > + * assigning memory to the guest. > + */ > + if (!folio_test_uptodate(folio)) { > + unsigned long nr_pages = folio_nr_pages(folio); > + unsigned long i; > + > + for (i = 0; i < nr_pages; i++) > + clear_highpage(folio_page(folio, i)); > + > + folio_mark_uptodate(folio); > + } > + > + /* > + * Ignore accessed, referenced, and dirty flags. The memory is > + * unevictable and there is no storage to write back to. > + */ > + return folio; > +} If VFIO wants to map a private page, is it required to call this function for PFN?