iommu: Add ops->domain_alloc_paging()

This callback requests the driver to create only a __IOMMU_DOMAIN_PAGING
domain, so it saves a few lines in a lot of drivers needlessly checking
the type.

More critically, this allows us to sweep out all the
IOMMU_DOMAIN_UNMANAGED and IOMMU_DOMAIN_DMA checks from a lot of the
drivers, simplifying what is going on in the code and ultimately removing
the now-unused special cases in drivers where they did not support
IOMMU_DOMAIN_DMA.

domain_alloc_paging() should return a struct iommu_domain that is
functionally compatible with ARM_DMA_USE_IOMMU, dma-iommu.c and iommufd.

Be forwards looking and pass in a 'struct device *' argument. We can
provide this when allocating the default_domain. No drivers will look at
this.

Tested-by: Steven Price <steven.price@arm.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/22-v8-81230027b2fa+9d-iommu_all_defdom_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 38856d542afc35a7d760d8721b3b2d88c9fea2b9..fe033043be467a27a840a17303ffeb31dec6b75c 100644 (file)
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2041,6 +2041,7 @@ void iommu_set_fault_handler(struct iommu_domain *domain,
 EXPORT_SYMBOL_GPL(iommu_set_fault_handler);
 
 static struct iommu_domain *__iommu_domain_alloc(const struct iommu_ops *ops,
+                                                struct device *dev,
                                                 unsigned int type)
 {
        struct iommu_domain *domain;
@@ -2048,8 +2049,13 @@ static struct iommu_domain *__iommu_domain_alloc(const struct iommu_ops *ops,
 
        if (alloc_type == IOMMU_DOMAIN_IDENTITY && ops->identity_domain)
                return ops->identity_domain;
+       else if (type & __IOMMU_DOMAIN_PAGING && ops->domain_alloc_paging)
+               domain = ops->domain_alloc_paging(dev);
+       else if (ops->domain_alloc)
+               domain = ops->domain_alloc(alloc_type);
+       else
+               return NULL;
 
-       domain = ops->domain_alloc(alloc_type);
        if (!domain)
                return NULL;
 
@@ -2074,14 +2080,19 @@ static struct iommu_domain *__iommu_domain_alloc(const struct iommu_ops *ops,
 static struct iommu_domain *
 __iommu_group_domain_alloc(struct iommu_group *group, unsigned int type)
 {
-       return __iommu_domain_alloc(group_iommu_ops(group), type);
+       struct device *dev =
+               list_first_entry(&group->devices, struct group_device, list)
+                       ->dev;
+
+       return __iommu_domain_alloc(group_iommu_ops(group), dev, type);
 }
 
 struct iommu_domain *iommu_domain_alloc(const struct bus_type *bus)
 {
        if (bus == NULL || bus->iommu_ops == NULL)
                return NULL;
-       return __iommu_domain_alloc(bus->iommu_ops, IOMMU_DOMAIN_UNMANAGED);
+       return __iommu_domain_alloc(bus->iommu_ops, NULL,
+                                   IOMMU_DOMAIN_UNMANAGED);
 }
 EXPORT_SYMBOL_GPL(iommu_domain_alloc);
 

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 511dfeea5272151e9910818f62e43d6c9121e847..3f173307434dcca261ac5b6c9d46e9bf2ad178d8 100644 (file)
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -239,6 +239,8 @@ struct iommu_iotlb_gather {
  *           use. The information type is one of enum iommu_hw_info_type defined
  *           in include/uapi/linux/iommufd.h.
  * @domain_alloc: allocate iommu domain
+ * @domain_alloc_paging: Allocate an iommu_domain that can be used for
+ *                       UNMANAGED, DMA, and DMA_FQ domain types.
  * @probe_device: Add device to iommu driver handling
  * @release_device: Remove device from iommu driver handling
  * @probe_finalize: Do final setup work after the device is added to an IOMMU
@@ -273,6 +275,7 @@ struct iommu_ops {
 
        /* Domain allocation and freeing by the iommu driver */
        struct iommu_domain *(*domain_alloc)(unsigned iommu_domain_type);
+       struct iommu_domain *(*domain_alloc_paging)(struct device *dev);
 
        struct iommu_device *(*probe_device)(struct device *dev);
        void (*release_device)(struct device *dev);