Messages in this thread | | | Date | Tue, 25 Jan 2022 00:20:26 +0000 | Subject | Re: [PATCH 6/7] iommu: Use right way to retrieve iommu_ops | From | Robin Murphy <> |
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On 2022-01-24 07:11, 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 > --- a/include/linux/iommu.h > +++ 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;
This probably warrants at least a WARN, but it's arguable to just assume that valid ops must be installed if iommu_probe_device() has succeeded. The device ops are essentially for internal use within the IOMMU subsystem itself, so we should be able to trust ourselves not to misuse the helper.
> +} > + > #define IOMMU_BUS_NOTIFY_PRIORITY 0 > #define IOMMU_GROUP_NOTIFY_ADD_DEVICE 1 /* Device added */ > #define IOMMU_GROUP_NOTIFY_DEL_DEVICE 2 /* Pre Device removed */ > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index 5230c6d90ece..6631e2ea44df 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -764,6 +764,7 @@ EXPORT_SYMBOL_GPL(iommu_group_set_name); > static int iommu_create_device_direct_mappings(struct iommu_group *group, > struct device *dev) > { > + 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);
Strictly I think this was a domain op, as it was about reserving the IOVA range in the given DMA domain. Also taking the domain as an argument is a bit of a giveaway. However it's now just dead code either way since there are no remaining implementations, and no reason for any new ones.
> > start = ALIGN(entry->start, pg_size); > end = ALIGN(entry->start + entry->length, pg_size); > @@ -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);
Similarly if this takes a domain as its first argument then it's de facto a domain method. However, I'd concur that logically it *is* a device op, so let's drop that (unused) domain argument if we're cleaning up.
Maybe there's even an argument for factoring this out to a standard flag in dev_iommu rather than an op at all?
The others covered here look OK - we can blame PCI for page response being weirdly device-centric - however could we also convert all the feasible instances of dev->bus->iommu_ops to dev_iommu_ops() as well? (Subtly implying that I'm also not a fan of having "_get" in the name for a non-refcounted lookup...) Obviously iommu_probe_device() and iommmu_domain_alloc() still need bus ops at this point, but I'm working on that... :)
Thanks, Robin.
> return false; > } > @@ -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; > @@ -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); > > return 0; > } > @@ -2020,7 +2023,7 @@ EXPORT_SYMBOL_GPL(iommu_attach_device); > > int iommu_deferred_attach(struct device *dev, struct iommu_domain *domain) > { > - const struct iommu_ops *ops = domain->ops; > + const struct iommu_ops *ops = dev_iommu_ops_get(dev); > > if (ops->is_attach_deferred && ops->is_attach_deferred(domain, dev)) > return __iommu_attach_device(domain, dev);
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