Messages in this thread | | | Date | Mon, 24 Jan 2022 13:36:50 -0400 | From | Jason Gunthorpe <> | Subject | Re: [PATCH 6/7] iommu: Use right way to retrieve iommu_ops |
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On Mon, Jan 24, 2022 at 03:11:01PM +0800, Lu Baolu wrote: > The common iommu_ops is hooked to both device and domain. When a helper > has both device and domain pointer, the way to get the iommu_ops looks > messy in iommu core. This sorts out the way to get iommu_ops. The device > related helpers go through device pointer, while the domain related ones > go through domain pointer. > > Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> > include/linux/iommu.h | 8 ++++++++ > drivers/iommu/iommu.c | 25 ++++++++++++++----------- > 2 files changed, 22 insertions(+), 11 deletions(-) > > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index aa5486243892..111b3e9c79bb 100644 > +++ b/include/linux/iommu.h > @@ -385,6 +385,14 @@ static inline void iommu_iotlb_gather_init(struct iommu_iotlb_gather *gather) > }; > } > > +static inline const struct iommu_ops *dev_iommu_ops_get(struct device *dev) > +{ > + if (dev && dev->iommu && dev->iommu->iommu_dev) > + return dev->iommu->iommu_dev->ops; > + > + return NULL;
What is the purpose of this helper?
> + const struct iommu_ops *ops = dev_iommu_ops_get(dev); > struct iommu_domain *domain = group->default_domain; > struct iommu_resv_region *entry; > struct list_head mappings; > @@ -785,8 +786,8 @@ static int iommu_create_device_direct_mappings(struct iommu_group *group, > dma_addr_t start, end, addr; > size_t map_size = 0; > > - if (domain->ops->apply_resv_region) > - domain->ops->apply_resv_region(dev, domain, entry); > + if (ops->apply_resv_region) > + ops->apply_resv_region(dev, domain, entry);
Here we call it and don't check for NULL? So why did we check the interior pointers in the helper?
> @@ -831,8 +832,10 @@ static int iommu_create_device_direct_mappings(struct iommu_group *group, > static bool iommu_is_attach_deferred(struct iommu_domain *domain, > struct device *dev) > { > - if (domain->ops->is_attach_deferred) > - return domain->ops->is_attach_deferred(domain, dev); > + const struct iommu_ops *ops = dev_iommu_ops_get(dev); > + > + if (ops->is_attach_deferred) > + return ops->is_attach_deferred(domain, dev);
Same here, at least return false if ops is null..
> @@ -1251,10 +1254,10 @@ int iommu_page_response(struct device *dev, > struct iommu_fault_event *evt; > struct iommu_fault_page_request *prm; > struct dev_iommu *param = dev->iommu; > + const struct iommu_ops *ops = dev_iommu_ops_get(dev); > bool has_pasid = msg->flags & IOMMU_PAGE_RESP_PASID_VALID; > - struct iommu_domain *domain = iommu_get_domain_for_dev(dev); > > - if (!domain || !domain->ops->page_response) > + if (!ops || !ops->page_response) > return -ENODEV; > > if (!param || !param->fault_param) > @@ -1295,7 +1298,7 @@ int iommu_page_response(struct device *dev, > msg->pasid = 0; > } > > - ret = domain->ops->page_response(dev, evt, msg); > + ret = ops->page_response(dev, evt, msg); > list_del(&evt->list); > kfree(evt); > break;
Feels weird that page_response is not connected to a domain, the fault originated from a domain after all. I would say this op should be moved to the domain and the caller should provide the a pointer to the domain that originated the fault.
Ideally since only some domain's will be configured to handle faults at all - domains that can't do this should have a NULL page_response op, even if other domains created by the same device driver could handle page_response..
> @@ -1758,10 +1761,10 @@ static int __iommu_group_dma_attach(struct iommu_group *group) > > static int iommu_group_do_probe_finalize(struct device *dev, void *data) > { > - struct iommu_domain *domain = data; > + const struct iommu_ops *ops = dev_iommu_ops_get(dev); > > - if (domain->ops->probe_finalize) > - domain->ops->probe_finalize(dev); > + if (ops->probe_finalize) > + ops->probe_finalize(dev);
This is an oddball one too, it is finishing setting up the default domain for a device? Several drivers seem to recover the default domain in their implementations..
Jason
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