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Tue, 29 Oct 2024 09:18:07 -0700 Date: Tue, 29 Oct 2024 09:18:05 -0700 From: Nicolin Chen To: Jason Gunthorpe CC: , , , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH v5 03/13] iommufd: Add iommufd_verify_unfinalized_object Message-ID: References: <20241029144907.GB209124@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20241029144907.GB209124@nvidia.com> X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ1PEPF00001CE3:EE_|CH3PR12MB8658:EE_ X-MS-Office365-Filtering-Correlation-Id: a9fc50a2-03bb-40aa-83b3-08dcf83550fc X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700013|7416014|376014|82310400026|1800799024; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?Z7xNHfJ0DISxTXvb58qOeG4Tl/w8hyLOk1chRTVMgXh2VPtdZrxIx3SlIvIZ?= =?us-ascii?Q?TLkKW+J7ADCI3HGxlhyXgNTk9vM1yauTuheKkwCVDsxx9gfkMZDxLFp24E90?= =?us-ascii?Q?W4dPdMylS06mMUQZPw8X/cYUM70fFjFSEViV0zf+OcFNeBqq8w4Ze5oY69tF?= =?us-ascii?Q?HObvye26rpM4RHRJ4NfRhtkosilKYiL0q5cdLwvW34DSaFigxr8zgjvNYLyN?= =?us-ascii?Q?fZLcWx+QL3o+atD/OcRCWyBXx3Z1ksCKxHs0lNQe/9+AgjiZAxZpfgbRu/se?= =?us-ascii?Q?w0hcepBCYXgR4M9+nZ/kmkXuNcPfP/x5FscWNxLmx3y4SlnGo9Uh6sHRO3Xn?= =?us-ascii?Q?6lTAIj1FSPEVithkbKAlZgIlcnp7h+i9sgcdI8Pmd4zYjNJM+MYsnSciy9Jd?= =?us-ascii?Q?j8IqEVQbv8ZOza7zWmntmvo0Xoxlcy5dQVnQp53Bds1aJAQrfHQWllcdtL0Y?= =?us-ascii?Q?troKoAUkAf18bRQVwZv0d1IUU78kroZpLEYi05hmsuLfz3OOngkWN98udDeD?= =?us-ascii?Q?y/817DfcA3o3DYbJBxGQ/HMM+a4gScj7JyTzMs+5b1eTjgVDH6G46cNVuAGn?= =?us-ascii?Q?i7mC0OhEEjm0A5IGx2X7JM2dMuG+RZDOt/IYT0PP5AeElr0ElWZoHTq46afa?= =?us-ascii?Q?Mrye5Wkd4zYrst9WdUDwcazBTSvVcQ/ewlBV8MQpg4fAFandJB7+1KD8GU/U?= =?us-ascii?Q?LWsx1NwZII9LivzMIBfOZqjf/xYJ7z6tHVZ+0KUCH56ZjX7EotFnjUdzNXBU?= =?us-ascii?Q?U15ZSVDqfuVFt8i8B6N4hx1oI+Ah20eFIKQiqg+K6KjoTkTtmi78KRiG7VQ2?= =?us-ascii?Q?P54lvw+PSeTODz2Y6zEEXvZLVte077fR1VVI+Lt0yYyxcKluVuuW5k76v4f5?= =?us-ascii?Q?mAPC9HJ/zxEDkAA+bP+ZQZ4cpPSwNwM97nKPbgZiQRTekkFG8LJA66oec12d?= =?us-ascii?Q?J/fap0Gklbx2ispWoO5/6y9cg3rJpdWVTKGvaVbHKfgXJgcc9i+mHX5F5E7q?= =?us-ascii?Q?jpGqLPif1EqIDiS1hiFfaWd9xYVfOgwD7sd/58jvi2TwCHBPn1liaojT3/Yo?= =?us-ascii?Q?b/HMRm+m0O9uc2D3oAe54LpbD0hT/rkwKwVfbROmBMU2zIC4o4I/G2wsnv7D?= =?us-ascii?Q?PQNGpCCT6uS6EwsOU2GlB/yAzlF3SFHRMBzlJ3oyl/Z2q1Fa4Om7k8aPzUyS?= =?us-ascii?Q?J6YwPUByUF/IotPRYjbzqJ2SkqUuhREFQBe6VYbGvxJalGRxpyS8UaNUSitx?= =?us-ascii?Q?lpvBJb90lYLTnSK8ZmUix/9kabqFogPnqvoO/+cxzCdNcCHukEsV91Q/J6nV?= =?us-ascii?Q?fH5nlhXMUrGTgGRl321L96iC/FvGHy4J2cHc4W9oXFJp6yiznmSDiGOnK4dA?= =?us-ascii?Q?HBoksIaIrTwgn+oSuLY01Zkp5SHE2QzkBYJRhdmKT550EpGfhA=3D=3D?= X-Forefront-Antispam-Report: CIP:216.228.117.161;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge2.nvidia.com;CAT:NONE;SFS:(13230040)(36860700013)(7416014)(376014)(82310400026)(1800799024);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Oct 2024 16:18:25.4199 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: a9fc50a2-03bb-40aa-83b3-08dcf83550fc X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.161];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: SJ1PEPF00001CE3.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB8658 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241029_091833_783267_C0ED0AAF X-CRM114-Status: GOOD ( 18.22 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Oct 29, 2024 at 11:49:07AM -0300, Jason Gunthorpe wrote: > On Fri, Oct 25, 2024 at 04:49:43PM -0700, Nicolin Chen wrote: > > To support driver-allocated vIOMMU objects, it's suggested to call the > > allocator helper in IOMMU dirvers. However, there is no guarantee that > > drivers will all use it and allocate objects properly. > > > > Add a helper for iommufd core to verify if an unfinalized object is at > > least reserved in the ictx. > > I don't think we need this.. > > iommufd_object_finalize() already does: > > old = xa_store(&ictx->objects, obj->id, obj, GFP_KERNEL); > /* obj->id was returned from xa_alloc() so the xa_store() cannot fail */ > WARN_ON(old); It feels unsafe to carry on the iommufd_viommu_alloc_ioctl() until iommufd_object_finalize() as the function would touch the returned faulty viommu pointer? E.g. what if the viommu has an even smaller size than struct iommufd_viommu? > So, we could enhance it to be more robust, like this patch is doing: > > void iommufd_object_finalize(struct iommufd_ctx *ictx, > struct iommufd_object *obj) > { > void *old; > > old = xa_cmpxchg(&ictx->objects, obj->id, XA_ZERO_ENTRY, obj, > GFP_KERNEL); > /* obj->id was returned from xa_alloc() so the xa_store() cannot fail */ > WARN_ON(old != XA_ZERO_ENTRY); > > It is always a driver bug to not initialize that object, so WARN_ON is > OK. I think we'd need the same change in iommufd_object_abort() too. Thanks Nicolin