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Shutemov" , "Michael Kelley (LINUX)" Cc: "Kirill A. Shutemov" , "dave.hansen@intel.com" , "tglx@linutronix.de" , "mingo@redhat.com" , "bp@alien8.de" , Dexuan Cui , "rick.p.edgecombe@intel.com" , "sathyanarayanan.kuppuswamy@linux.intel.com" , "seanjc@google.com" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" References: <20230606095622.1939-1-kirill.shutemov@linux.intel.com> <20230707140633.jzuucz52d7jdc763@box.shutemov.name> <20230709060904.w3czdz23453eyx2h@box.shutemov.name> From: Tom Lendacky In-Reply-To: <20230709060904.w3czdz23453eyx2h@box.shutemov.name> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SN6PR08CA0010.namprd08.prod.outlook.com (2603:10b6:805:66::23) To DM4PR12MB5229.namprd12.prod.outlook.com (2603:10b6:5:398::12) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DM4PR12MB5229:EE_|LV8PR12MB9109:EE_ X-MS-Office365-Filtering-Correlation-Id: 94eef198-e76c-4db7-ebe4-08db814dd400 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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Shutemov wrote: > On Sat, Jul 08, 2023 at 11:53:08PM +0000, Michael Kelley (LINUX) wrote: >> From: Kirill A. Shutemov Sent: Friday, July 7, 2023 7:07 AM >>> >>> On Thu, Jul 06, 2023 at 04:48:32PM +0000, Michael Kelley (LINUX) wrote: >>>> From: Kirill A. Shutemov Sent: Tuesday, June 6, 2023 2:56 AM >> >> [snip] >> >>> >>> It only addresses the problem that happens on transition, but >>> load_unaligned_zeropad() is still a problem for the shared mappings in >>> general, after transition is complete. Like if load_unaligned_zeropad() >>> steps from private to shared mapping and shared mapping triggers #VE, >>> kernel should be able to handle it. >> >> I'm showing my ignorance of TDX architectural details, but what's the >> situation where shared mappings in general can trigger a #VE? How >> do such situations get handled for references that aren't from >> load_unaligned_zeropad()? >> > > Shared mappings are under host/VMM control. It can just not map the page > in shared-ept and trigger ept-violation #VE. > >>> Any comments? >> >> This looks good to me. I applied the diff to a TDX VM running on >> Hyper-V. When a load_unaligned_zeropad() occurs on a page that is >> transitioning between private and shared, the zeropad fixup is now >> done correctly via the #VE handler. (This is *without* my RFC patch to >> mark the pages invalid during a transition.) > > Great. > > I am at vacation for the next two weeks. I will prepare a proper patch > when I am back. Feel free to make patch yourself if you feel it is urgent. > Michael, Are you still pursuing the RFC patch, then? Just trying to decide whether a patch will be needed for SNP... Thanks, Tom