Messages in this thread | | | Subject | Re: [PATCH 6/7] iommu: Use right way to retrieve iommu_ops | From | Lu Baolu <> | Date | Tue, 25 Jan 2022 11:18:01 +0800 |
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On 1/25/22 1:36 AM, Jason Gunthorpe wrote: > 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?
Get the iommu_ops from a device pointer. Just want to avoid duplicate code in various functions.
> >> + 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?
Yes. Should check.
> >> @@ -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..
Yes.
> >> @@ -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..
In order to avoid default domain type (DMA or IDENDITY) conflict among devices in a same iommu_group, the probe process is divided into two phases, one for determining the default domain type and the other for allocating the default domain and attaching it to the device.
ops->probe_finalize() is called to tell the vendor iommu driver that the device probe is done. Normally the vendor iommu driver could set the dma ops in this callback.
> > Jason >
Best regards, baolu
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