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Mon, 11 Nov 2024 08:18:07 +0000 Message-ID: Date: Mon, 11 Nov 2024 16:22:44 +0800 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 1/7] iommu: Prevent pasid attach if no ops->remove_dev_pasid To: Baolu Lu , , , CC: , , , , , , , , References: <20241108120427.13562-1-yi.l.liu@intel.com> <20241108120427.13562-2-yi.l.liu@intel.com> Content-Language: en-US From: Yi Liu In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: SI2PR02CA0054.apcprd02.prod.outlook.com (2603:1096:4:196::13) To DS0PR11MB7529.namprd11.prod.outlook.com (2603:10b6:8:141::20) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS0PR11MB7529:EE_|SN7PR11MB6604:EE_ X-MS-Office365-Filtering-Correlation-Id: be68cd66-6f16-42d7-74dd-08dd02295f2d X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|376014|366016|1800799024; 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In reality, it is impossible that an >> iommu driver implements set_dev_pasid() but no remove_dev_pasid() op. >> However, >> it is better to check it. >> >> Reviewed-by: Jason Gunthorpe >> Reviewed-by: Kevin Tian >> Signed-off-by: Yi Liu >> --- >>   drivers/iommu/iommu.c | 6 ++++-- >>   1 file changed, 4 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c >> index 13fcd9d8f2df..1c689e57928e 100644 >> --- a/drivers/iommu/iommu.c >> +++ b/drivers/iommu/iommu.c >> @@ -3352,17 +3352,19 @@ int iommu_attach_device_pasid(struct iommu_domain >> *domain, >>                     struct iommu_attach_handle *handle) >>   { >>       /* Caller must be a probed driver on dev */ >> +    const struct iommu_ops *ops = dev_iommu_ops(dev); >>       struct iommu_group *group = dev->iommu_group; >>       struct group_device *device; >>       int ret; >> -    if (!domain->ops->set_dev_pasid) >> +    if (!domain->ops->set_dev_pasid || >> +        !ops->remove_dev_pasid) >>           return -EOPNOTSUPP; >>       if (!group) >>           return -ENODEV; > > If group is NULL, calling dev_iommu_ops() will trigger a kernel NULL > pointer reference warning, which is unintended. If you need to check > ops->remove_dev_pasid, it should be done after the group check. > good catch. Let me fix it. -- Regards, Yi Liu