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Wed, 12 Oct 2022 04:36:50 +0000 Received: from MN2PR11MB3728.namprd11.prod.outlook.com ([fe80::e2ed:a3a2:6ffe:409e]) by MN2PR11MB3728.namprd11.prod.outlook.com ([fe80::e2ed:a3a2:6ffe:409e%5]) with mapi id 15.20.5709.019; Wed, 12 Oct 2022 04:36:49 +0000 Message-ID: <2dd703b6-66a9-0a35-b02e-6a66e356277f@intel.com> Date: Wed, 12 Oct 2022 12:42:10 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.2.2 Subject: Re: [PATCH v9 2/3] x86/sgx: Introduce union with vepc_vaddr field for virtualization case To: Dave Hansen , , , , CC: , , , , , References: <20220920063948.3556917-1-zhiquan1.li@intel.com> <20220920063948.3556917-3-zhiquan1.li@intel.com> <540df1d4-d784-b33e-e1e3-573aa5f804c6@intel.com> <277c494c-7e55-2d73-dbf3-7a841836a395@intel.com> Content-Language: en-US From: Zhiquan Li In-Reply-To: <277c494c-7e55-2d73-dbf3-7a841836a395@intel.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SG2PR01CA0187.apcprd01.prod.exchangelabs.com (2603:1096:4:189::12) To MN2PR11MB3728.namprd11.prod.outlook.com (2603:10b6:208:f4::21) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MN2PR11MB3728:EE_|DM4PR11MB7279:EE_ X-MS-Office365-Filtering-Correlation-Id: e4b0dab4-56b4-48f1-16c6-08daac0b6068 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; 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Thanks for your comments, Dave. I added more descriptions for motivation and reduced explanations for details in changelog as below, could you help me review if it is easier to understand now? When a page triggers a machine check, it only reports the PFN. But in order to inject #MC into VM through hypervisor, the virtual address of virtual EPC page is required. To avoid introduce a new dedicated structure to track it, repurpose the 'encl_owner' field as it is useless in virtualization case, so that arch_memory_failure() can retrieve the virtual address easily and attach it to the extra info of SIGBUS which will be sent to hypervisor. The union can prevent playing the casting games while using it. And add a new EPC page flag - SGX_EPC_PAGE_KVM_GUEST to interpret the meaning of the field. The changes take place while allocating an EPC page to a KVM guests. After applying it, the reversed relationship from an EPC page to virtual EPC doesn't exist, in practice, such relationship is useless. Beyond that, other behaviors have not been changed. Furthermore, may I change the subject as below to highlight the motivation? x86/sgx: track virtual address of virtual EPC page for injecting #MC into VM Best Regards, Zhiquan