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Date: Wed, 4 Mar 2026 16:46:44 +0100 From: Roger Pau =?utf-8?B?TW9ubsOp?= To: Jan Beulich Cc: Stewart Hildebrand , Ariadne Conill , Steven Noonan , xen-devel@lists.xenproject.org Subject: Re: [PATCH] xen/vpci: zero guest-visible BAR addresses to ensure domU asssigns its own Message-ID: References: <20260224231216.6203-1-ariadne@ariadne.space> <2aef1aab-f1f4-4063-8c61-d26ae335d06f@suse.com> Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: MR1P264CA0066.FRAP264.PROD.OUTLOOK.COM (2603:10a6:501:3e::14) To CH7PR03MB7860.namprd03.prod.outlook.com (2603:10b6:610:24e::14) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH7PR03MB7860:EE_|CH3PR03MB7341:EE_ X-MS-Office365-Filtering-Correlation-Id: b885b062-304b-4547-fe05-08de7a053efe X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|376014|366016; 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:CH7PR03MB7860.namprd03.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(376014)(366016);DIR:OUT;SFP:1101; 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Assuming we want to move the code change forward, for v2 of the patch I > > suggest dropping the 2nd half of the title, and reworking the commit description > > to focus on describing the code change at hand and less on what the domU might > > do. > > That would indeed work for me. +1. The "try to map them with the IOMMU" wording is not accurate IMO, and wants replacing. It would also be nice to mention that zeroing unconditionally is fine, because for domUs the memory decoding bit is also unconditionally cleared, so there will be no attempt to map the BARs into the guest p2m by vpci_init_header(). Thanks, Roger.