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Shutemov" Subject: Re: [RFC PATCH v12 18/33] KVM: x86/mmu: Handle page fault for private memory Message-ID: Reply-To: Yan Zhao References: <20230914015531.1419405-1-seanjc@google.com> <20230914015531.1419405-19-seanjc@google.com> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20230914015531.1419405-19-seanjc@google.com> X-ClientProxiedBy: SI2PR02CA0050.apcprd02.prod.outlook.com (2603:1096:4:196::11) To DS7PR11MB5966.namprd11.prod.outlook.com (2603:10b6:8:71::6) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS7PR11MB5966:EE_|BN9PR11MB5242:EE_ X-MS-Office365-Filtering-Correlation-Id: 2565bab3-13d1-47da-6156-08dbb5b21f53 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: 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 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)(136003)(396003)(346002)(39860400002)(366004)(376002)(451199024)(1800799009)(186009)(6506007)(6486002)(7416002)(7406005)(6512007)(2906002)(26005)(66556008)(3450700001)(5660300002)(38100700002)(66476007)(316002)(8676002)(4326008)(41300700001)(8936002)(6916009)(54906003)(66946007)(82960400001)(6666004)(478600001)(86362001)(83380400001);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?oGkly7Efjpo2HEAbxPMZ4aGaRk5erelMBtYaeumhRSf4JPCcurMCNUlhg6XS?= =?us-ascii?Q?rR03HAnPXj0TXpRj6S5dCtd9r2fZHRsEZrCNvvh4od2lCl9b0lTcKhKs5L5T?= =?us-ascii?Q?vGdOizc0+Bb9ThdIj19RlqORbIW7tNqOnSwuu+GkyXRUz+RjjgvZtvH0HMtG?= =?us-ascii?Q?1nqnOgV4aSBAJi4J7QDjZCHKSA34Rnly+gc+2ARRYA9ihvbjk43QxxQRa0as?= =?us-ascii?Q?H4Khy39GIXg/rL/EUmC6OQQUBsbGJhdXrfnALvOE339+qenGJS0TD6g4N8sz?= =?us-ascii?Q?FFo7rHn+Z/fLfvACJobHwdbiit/APLktfaLTShYpl/aITPD4abUXeLNzb2gj?= =?us-ascii?Q?a1w88RH4bHeLOWtbtixiwS1mYr09WDxzFuaMNfxYYmK4S2rjuSvxAkUyYcab?= =?us-ascii?Q?9/o6FjexIl0lP+Yj37fGg/jcdiDt6lU/IKLagqRQvUJ33ULbO7u6dWCLO89L?= =?us-ascii?Q?Bju9PhWKAbrEod6tC0/rn4abWlVCQ44TVg2qPXYdQndBa6Gh5bdOMB13dfU5?= =?us-ascii?Q?+omdo1Afi2bEQ8GF4BLtQb0e4l44o3jX43Y4CBWVD9TinfYHX1cGUILcxdWr?= =?us-ascii?Q?bHoLWouNRfzuN1kU11hwKP1xi9fTmDkT2wnfaZU+Al1/2Ud0RHqh6t4bmgCg?= =?us-ascii?Q?0WtgrewIRrjHgQYjHDN9FdCu7/ha+Q9nR69xbrCyJ+ctDJlj9cq3I3aEyK8m?= =?us-ascii?Q?YoOxA42ph6t331rDokxzABFOas+fJKbADCfrxC4NpOdBh7cxU2UdMokWPUXa?= =?us-ascii?Q?jexYETkzp8NV5X9EW7iFP30CKoZC1fpyY969hN69zjhWrOKLL2Rsk0LANxUC?= =?us-ascii?Q?xjuFyKpecKlBLcvfrFRBVR7VS1i212OHf6qK24rnTHZCKoOcSfoabZOHUxXo?= =?us-ascii?Q?yh85Npo/kTOW7HzVlJgjwu5bmYaEA6mA0LD3tJxB2faWz5lJ7kWat+P9GRde?= =?us-ascii?Q?MLEirzmJPCTi+ZKo8leXrRC+ttG2joFcRHg114jxmSBgg0PWQA+Rn+kmj0u2?= =?us-ascii?Q?4qURY/EVoGDdPuVZwDm+GxoRAruzKwDrzpuw5QVr1IdpkCkxGvXmIZnUTj8p?= =?us-ascii?Q?atWkBapA8ihG8/PXz/IVOqwnNKaY4AfQttxv1Vp5j+GjsKabo3IplExvObGn?= =?us-ascii?Q?kY5UZu5DAJuH6eNOpXCk/gFw2VSeYKZER9eztJPRuZ7Hhh+HpFUdWvR9xkE4?= =?us-ascii?Q?KNlovuUmfpSLj+IdIiJ025QnXHeT728U4ppH1cXl8Bq4cJf5jk6HGPsTnsjj?= =?us-ascii?Q?P+9GymwmG0UFmWCgVww2wzZ7U8h4OS7Xp9vFjSU9MC3pNNlsDwJtS5PfN9SC?= =?us-ascii?Q?LiELTa9f0zFLnfZY/IIsWbENc1d2ar13W3PuwXetj100K6LccieSIln8lv1h?= =?us-ascii?Q?1YBwPObMB1bYptkBMDuoV5WruEdMGzT6xDvF2JBjIXeSoNtTq6B5C68dQ8YI?= =?us-ascii?Q?NhWBBlpJiT/miwAlrVpOzicMpQ9eAWLItd3n+auG63KRdn+IQ1peEcb4nSrd?= =?us-ascii?Q?6UEGqT3MjD7LtckP/0+O3PH/7/eVwGgR/nVg4Cg/1t6t4XpCVJ/zAwADOPz2?= =?us-ascii?Q?gKG2iP58jk+EdSvqLD+fHoD4iw1lAqQt+g0sN2p3?= X-MS-Exchange-CrossTenant-Network-Message-Id: 2565bab3-13d1-47da-6156-08dbb5b21f53 X-MS-Exchange-CrossTenant-AuthSource: DS7PR11MB5966.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Sep 2023 06:08:04.0409 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 3BqdQQt6ZGtrfK54GbYMi54+OeE95wRqXTESwBFb5sP4OU+uWGKyzzSwlaywaLAnTI3P5b9sVJMBR7ffdEqLyQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN9PR11MB5242 X-OriginatorOrg: intel.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 13, 2023 at 06:55:16PM -0700, Sean Christopherson wrote: .... > +static void kvm_mmu_prepare_memory_fault_exit(struct kvm_vcpu *vcpu, > + struct kvm_page_fault *fault) > +{ > + kvm_prepare_memory_fault_exit(vcpu, fault->gfn << PAGE_SHIFT, > + PAGE_SIZE, fault->write, fault->exec, > + fault->is_private); > +} > + > +static int kvm_faultin_pfn_private(struct kvm_vcpu *vcpu, > + struct kvm_page_fault *fault) > +{ > + int max_order, r; > + > + if (!kvm_slot_can_be_private(fault->slot)) { > + kvm_mmu_prepare_memory_fault_exit(vcpu, fault); > + return -EFAULT; > + } > + > + r = kvm_gmem_get_pfn(vcpu->kvm, fault->slot, fault->gfn, &fault->pfn, > + &max_order); > + if (r) { > + kvm_mmu_prepare_memory_fault_exit(vcpu, fault); > + return r; > + } > + > + fault->max_level = min(kvm_max_level_for_order(max_order), > + fault->max_level); > + fault->map_writable = !(fault->slot->flags & KVM_MEM_READONLY); > + > + return RET_PF_CONTINUE; > +} > + > static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) > { > struct kvm_memory_slot *slot = fault->slot; > @@ -4293,6 +4356,14 @@ static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault > return RET_PF_EMULATE; > } > > + if (fault->is_private != kvm_mem_is_private(vcpu->kvm, fault->gfn)) { In patch 21, fault->is_private is set as: ".is_private = kvm_mem_is_private(vcpu->kvm, cr2_or_gpa >> PAGE_SHIFT)", then, the inequality here means memory attribute has been updated after last check. So, why an exit to user space for converting is required instead of a mere retry? Or, is it because how .is_private is assigned in patch 21 is subjected to change in future? > + kvm_mmu_prepare_memory_fault_exit(vcpu, fault); > + return -EFAULT; > + } > + > + if (fault->is_private) > + return kvm_faultin_pfn_private(vcpu, fault); > + > async = false; > fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn, false, false, &async, > fault->write, &fault->map_writable, > @@ -7184,6 +7255,19 @@ void kvm_mmu_pre_destroy_vm(struct kvm *kvm) > } >