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Peter Anvin" , Michael Roth , Joerg Roedel , Andy Lutomirski , Peter Zijlstra References: <20220614120231.48165-1-kirill.shutemov@linux.intel.com> <658c455c40e8950cb046dd885dd19dc1c52d060a.1659103274.git.thomas.lendacky@amd.com> From: Tom Lendacky In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SA9PR10CA0023.namprd10.prod.outlook.com (2603:10b6:806:a7::28) To DM4PR12MB5229.namprd12.prod.outlook.com (2603:10b6:5:398::12) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 2b31613f-71db-4bf1-2ea4-08da716e2c2e X-MS-TrafficTypeDiagnostic: MN2PR12MB3150:EE_ 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:DM4PR12MB5229.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230016)(4636009)(366004)(396003)(376002)(136003)(39860400002)(346002)(83380400001)(6512007)(26005)(6506007)(186003)(2616005)(38100700002)(53546011)(66556008)(36756003)(8676002)(4326008)(66946007)(2906002)(5660300002)(7416002)(8936002)(966005)(41300700001)(66476007)(478600001)(316002)(54906003)(31696002)(6486002)(31686004)(86362001)(43740500002)(45980500001);DIR:OUT;SFP:1101; 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>> + >> + /* >> + * Page State Change structure for use when accepting memory or when >> + * changing page state. Interrupts are disabled when using the structure >> + * but an NMI could still be raised, so use a flag to indicate when the >> + * structure is in use and use the MSR protocol in these cases. >> + */ >> + struct snp_psc_desc psc_desc; >> + bool psc_active; >> }; > > This thing: > > struct snp_psc_desc { > struct psc_hdr hdr; > struct psc_entry entries[VMGEXIT_PSC_MAX_ENTRY]; > } __packed; > > is 16k, right? Being per-cpu, this might eat up a MB or two of memory > on a big server? It's just under 2K, 2,032 bytes. > > Considering that runtime acceptance is already single-threaded[1] *and* > there's a fallback method, why not just have a single copy of this > guarded by a single lock? This function is called for more than just memory acceptance. It's also called for any changes from or to private or shared, which isn't single-threaded. Thanks, Tom > > 1. > https://lore.kernel.org/all/20220614120231.48165-10-kirill.shutemov@linux.intel.com/