iommu: Allow ops->default_domain to work when !CONFIG_IOMMU_DMA

The ops->default_domain flow used a 0 req_type to select the default
domain and this was enforced by iommu_group_alloc_default_domain().

When !CONFIG_IOMMU_DMA started forcing the old ARM32 drivers into IDENTITY
it also overroad the 0 req_type of the ops->default_domain drivers to
IDENTITY which ends up causing failures during device probe.

Make iommu_group_alloc_default_domain() accept a req_type that matches the
ops->default_domain and have iommu_group_alloc_default_domain() generate a
req_type that matches the default_domain.

This way the req_type always describes what kind of domain should be
attached and ops->default_domain overrides all other mechanisms to choose
the default domain.

Fixes: 2ad56efa80db ("powerpc/iommu: Setup a default domain and remove set_platform_dma_ops")
Fixes: 0f6a90436a57 ("iommu: Do not use IOMMU_DOMAIN_DMA if CONFIG_IOMMU_DMA is not enabled")
Reported-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Closes: https://lore.kernel.org/linux-iommu/20240123165829.630276-1-ovidiu.panait@windriver.com/
Reported-by: Shivaprasad G Bhat <sbhat@linux.ibm.com>
Closes: https://lore.kernel.org/linux-iommu/170618452753.3805.4425669653666211728.stgit@ltcd48-lp2.aus.stglab.ibm.com/
Tested-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Tested-by: Shivaprasad G Bhat <sbhat@linux.ibm.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/0-v1-755bd21c4a64+525b8-iommu_def_dom_fix_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 68e648b55767060204a8f42d1927c09ebacad39a..d14413916f93a01626e850aa72ee0c919c1f72bd 100644 (file)
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1799,7 +1799,7 @@ iommu_group_alloc_default_domain(struct iommu_group *group, int req_type)
         * domain. Do not use in new drivers.
         */
        if (ops->default_domain) {
-               if (req_type)
+               if (req_type != ops->default_domain->type)
                        return ERR_PTR(-EINVAL);
                return ops->default_domain;
        }
@@ -1871,10 +1871,18 @@ static int iommu_get_def_domain_type(struct iommu_group *group,
        const struct iommu_ops *ops = dev_iommu_ops(dev);
        int type;
 
-       if (!ops->def_domain_type)
-               return cur_type;
-
-       type = ops->def_domain_type(dev);
+       if (ops->default_domain) {
+               /*
+                * Drivers that declare a global static default_domain will
+                * always choose that.
+                */
+               type = ops->default_domain->type;
+       } else {
+               if (ops->def_domain_type)
+                       type = ops->def_domain_type(dev);
+               else
+                       return cur_type;
+       }
        if (!type || cur_type == type)
                return cur_type;
        if (!cur_type)