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Wed, 8 May 2024 06:06:32 +0000 Received: from DS0PR11MB7529.namprd11.prod.outlook.com ([fe80::d244:15cd:1060:941a]) by DS0PR11MB7529.namprd11.prod.outlook.com ([fe80::d244:15cd:1060:941a%7]) with mapi id 15.20.7544.041; Wed, 8 May 2024 06:06:31 +0000 Message-ID: <07e0547d-1ece-4848-8e59-393013b75da8@intel.com> Date: Wed, 8 May 2024 14:10:05 +0800 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 12/12] iommu/vt-d: Add set_dev_pasid callback for nested domain Content-Language: en-US To: Jason Gunthorpe CC: Baolu Lu , "Tian, Kevin" , "joro@8bytes.org" , "alex.williamson@redhat.com" , "robin.murphy@arm.com" , "eric.auger@redhat.com" , "nicolinc@nvidia.com" , "kvm@vger.kernel.org" , "chao.p.peng@linux.intel.com" , "iommu@lists.linux.dev" , "Duan, Zhenzhong" , "Pan, Jacob jun" References: <20240412081516.31168-1-yi.l.liu@intel.com> <20240412081516.31168-13-yi.l.liu@intel.com> <20240506133635.GJ3341011@nvidia.com> <14a7b83e-0e5b-4518-a5d5-5f4d48aa6f2b@intel.com> <20240507151847.GQ3341011@nvidia.com> From: Yi Liu In-Reply-To: <20240507151847.GQ3341011@nvidia.com> Content-Type: text/plain; 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In the attach paths, it should return -EINVAL >>>> directly if the domain is not compatible with the iommu for the device. >>> >>> Yes, and this is already true for PASID. >> >> I'm not quite get why it is already true for PASID. I think Baolu's remark >> is general to domains attached to either RID or PASID. >> >>> I feel we could reasonably insist that domanis used with PASID are >>> allocated with a non-NULL dev. >> >> Any special reason for this disclaim? > > If it makes the driver easier, why not? yep. > PASID is special since PASID is barely used, we could insist that > new PASID users also use the new domian_alloc API. Ok. I have one doubt on how to make it in iommufd core. Shall the iommufd core call ops->domain_alloc_paging() directly or still call ops->domain_alloc_user() while ops->domain_alloc_user() flows into the paging domain allocation with non-null dev? > >> I agree implementing alloc_domain_paging() is the final solution to avoid >> such dynamic modifications to domain's caps. If it's really needed for >> PASID series now, I can add it in next version. :) > > Well, if it is needed. If you can do this some other way that is > reasonable then sure At first, I'd like to keep this agaw check here and remove it after implementing the ops->domain_alloc_paging() and retire domain_alloc op in intel iommu driver side. I have such thoughts as the RID and PASID attach path have the same concern w.r.t. agaw and other caps :) -- Regards, Yi Liu