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 <[email protected]>
> 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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