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Thu, 13 Mar 2025 19:07:25 +0000 Message-ID: <2a25d2c8-6b2e-443b-98aa-723dea2c9e78@intel.com> Date: Thu, 13 Mar 2025 21:07:15 +0200 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC] KVM: TDX: Defer guest memory removal to decrease shutdown time To: Paolo Bonzini CC: , , , , , , , , , , , , References: <20250313181629.17764-1-adrian.hunter@intel.com> Content-Language: en-US From: Adrian Hunter Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-ClientProxiedBy: MI2P293CA0011.ITAP293.PROD.OUTLOOK.COM (2603:10a6:290:45::11) To BYAPR11MB3605.namprd11.prod.outlook.com (2603:10b6:a03:f5::33) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BYAPR11MB3605:EE_|PH0PR11MB5808:EE_ X-MS-Office365-Filtering-Correlation-Id: f6393a76-0e6b-4579-22ce-08dd62624a79 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|1800799024|366016; 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This more efficient method was >> previously used in earlier versions of the TDX patches, but was removed to >> simplify the initial upstreaming. This is an RFC, and still needs a proper >> upstream commit log. It is intended to be an eventual follow up to base >> support. > > In the latest code the HKID is released in kvm_arch_pre_destroy_vm(). I am looking at kvm-coco-queue > That is before kvm_free_memslot() calls kvm_gmem_unbind(), which > results in fput() and hence kvm_gmem_release(). > > So, as long as userspace doesn't remove the memslots and close the > guestmemfds, shouldn't the TD_TEARDOWN method be usable? kvm_arch_pre_destroy_vm() is called from kvm_destroy_vm() which won't happen before kvm_gmem_release() calls kvm_put_kvm().