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Tue, 29 Sep 2026 10:08:49 +0000 Date: Tue, 29 Sep 2026 03:08:47 -0700 From: Peter Fang To: Dave Hansen CC: Dave Hansen , Kiryl Shutsemau , Rick Edgecombe , "Kuppuswamy Sathyanarayanan" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , , "H. Peter Anvin" , , , , Xiaoyao Li , Binbin Wu , Tony Lindgren , Sean Christopherson , Artem Bityutskiy 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> <0c6bc71f-53fb-4240-83a3-c52d090044d3@intel.com> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <0c6bc71f-53fb-4240-83a3-c52d090044d3@intel.com> X-ClientProxiedBy: SJ0PR13CA0119.namprd13.prod.outlook.com (2603:10b6:a03:2c5::34) To CH3PR11MB435924.namprd11.prod.outlook.com (2603:10b6:610:34a::8) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH3PR11MB435924:EE_|SJ0PR11MB4927:EE_ X-MS-Office365-Filtering-Correlation-Id: 16e93e32-4922-4e2d-1f4f-08df1e11a838 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|7416014|376014|1800799024|23010399003|10067099003|11063799006|56012099006|4143699003|22082099003|18002099003; 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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 is gloriously unencumbered by unwieldy comments! > > > Please explain the goal of this function. Why is it doing what it is > doing? This should also explain why it is page-aligning and caching things. Ugh sorry, this is a miss on my part. I will add comments to explain this, especially the caching part. > > Which also reminds me, it really isn't calculating the size of the quote > "buf". It's calculating the size of the allocation required to transport > it around, no? > > Because, there are three sizes here: > > 1. The actual data of the quote > 2. The size of #1 with the metadata added in > 3. The size of #2 with page padding > > Which one of those three is "buf_size", eh? I think what Rick said makes sense. A more limited change would be to choose 2 and let alloc/free deal with the page alignment. None of this is explained until patch 6. I'll add a comment for this. Thanks.