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Tue, 29 Sep 2026 16:38:36 +0000 Date: Tue, 29 Sep 2026 09:38:33 -0700 From: Peter Fang To: "Edgecombe, Rick P" CC: "sathyanarayanan.kuppuswamy@linux.intel.com" , "kas@kernel.org" , "dave.hansen@linux.intel.com" , "seanjc@google.com" , "bp@alien8.de" , "x86@kernel.org" , "binbin.wu@linux.intel.com" , "hpa@zytor.com" , "mingo@redhat.com" , "linux-kernel@vger.kernel.org" , "Li, Xiaoyao" , "tglx@kernel.org" , "kvm@vger.kernel.org" , "linux-coco@lists.linux.dev" , "Bityutskiy, Artem" , "tony.lindgren@linux.intel.com" Subject: Re: [PATCH v5 4/6] virt: tdx-guest: Add a helper for the Quote buffer size Message-ID: References: <20260928100913.2265687-1-peter.fang@intel.com> <20260928100913.2265687-5-peter.fang@intel.com> <27febde6bbd1142222f0a21db4e5180e0bd3261c.camel@intel.com> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <27febde6bbd1142222f0a21db4e5180e0bd3261c.camel@intel.com> X-ClientProxiedBy: SJ0PR03CA0164.namprd03.prod.outlook.com (2603:10b6:a03:338::19) To CH3PR11MB435924.namprd11.prod.outlook.com (2603:10b6:610:34a::8) Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH3PR11MB435924:EE_|SJ0PR11MB5770:EE_ X-MS-Office365-Filtering-Correlation-Id: c48c991a-c32e-4cb5-d594-08df1e481bb3 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|366016|23010399003|1800799024|18002099003|22082099003|10067099003|56012099006|11063799006|4143699003; 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> > + > > + if (quote_buf_size) > > + return quote_buf_size; > > + > > + quote_buf_size = PAGE_ALIGN(TDX_DEFAULT_QUOTE_SIZE); > > + > > + return quote_buf_size; > > +} > > + > > This makes no sense, at the point of this patch. It lazily sets a global to a > constant value. Function scoped static is also weird. > > I think you are doing it this way so that later you can plug in the dynamic > read. But later it still doesn't make sense why to lazily fetch it. Why not just > read it in the tdx_guest_init() to a global? If the read fails, set to > TDX_DEFAULT_QUOTE_SIZE. Then you are done. All callers of tdx_guest_init() just > refer to the global. Why not? After some offline discussion with Dave and Rick, the conclusion was that KISS is better. Just read this metadata field each time and assume the TDX module won't change it (because it shouldn't). That also gets rid of the static variable.