Messages in this thread | | | Date | Wed, 29 Mar 2023 14:18:10 +0800 | Subject | Re: [PATCH v2 5/8] iommu/vt-d: Make device pasid attachment explicit | From | Baolu Lu <> |
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On 3/28/23 3:44 PM, Tian, Kevin wrote: >> From: Baolu Lu <baolu.lu@linux.intel.com> >> Sent: Tuesday, March 28, 2023 1:49 PM >> >> On 3/28/23 7:21 AM, Jacob Pan wrote: >>> diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h >>> index 65b15be72878..b6c26f25d1ba 100644 >>> --- a/drivers/iommu/intel/iommu.h >>> +++ b/drivers/iommu/intel/iommu.h >>> @@ -595,6 +595,7 @@ struct dmar_domain { >>> >>> spinlock_t lock; /* Protect device tracking lists */ >>> struct list_head devices; /* all devices' list */ >>> + struct list_head dev_pasids; /* all attached pasids */ >>> >>> struct dma_pte *pgd; /* virtual address */ >>> int gaw; /* max guest address width */ >>> @@ -708,6 +709,7 @@ struct device_domain_info { >>> u8 ats_supported:1; >>> u8 ats_enabled:1; >>> u8 dtlb_extra_inval:1; /* Quirk for devices need extra flush */ >>> + u8 dev_attached:1; /* Device context activated */ >>> u8 ats_qdep; >>> struct device *dev; /* it's NULL for PCIe-to-PCI bridge */ >>> struct intel_iommu *iommu; /* IOMMU used by this device */ >>> @@ -715,6 +717,12 @@ struct device_domain_info { >>> struct pasid_table *pasid_table; /* pasid table */ >>> }; >>> >>> +struct device_pasid_info { >>> + struct list_head link_domain; /* link to domain siblings */ >>> + struct device *dev; /* physical device derived from */ >>> + ioasid_t pasid; /* PASID on physical device */ >>> +}; >> >> The dev_pasids list seems to be duplicate with iommu_group::pasid_array. >> >> The pasid_array is de facto per-device as the PCI subsystem requires ACS >> to be enabled on the upstream path to the root port. >> >> pci_enable_pasid(): >> 385 if (!pci_acs_path_enabled(pdev, NULL, PCI_ACS_RR | PCI_ACS_UF)) >> 386 return -EINVAL; >> >> For such PCI topology, pci_device_group() always assigns an exclusive >> iommu group (a.k.a. singleton group). >> >> So, how about moving the pasid_array from struct iommu_group to struct >> dev_iommu? With this refactoring, the individual iommu driver has no >> need to create their own pasid array or list. >> >> Instead of using iommu_group::mutex, perhaps the pasid_array needs its >> own lock in struct dev_iommu after moving. >> > > What you suggested is a right thing and more friendly to pasid attach > in iommufd [1]. > > but dev_pasids list here is a different thing. It tracks which [device, pasid] > is attached to the domain. w/o this information you'll have to walk the > pasid_array of every attached device under the domain and search for > every pasid entry pointing to the said domain. It's very inefficient. > > of course if this can be done more generally it'd be nice.😊 > > [1] https://lore.kernel.org/linux-iommu/ZAjbDxSzxYPqSCjo@nvidia.com/
Ah, yes. You are right. I was confused.
Best regards, baolu
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