arm64/dma-mapping: Remove default domain workaround

With the IOMMU core now taking care of default domains for groups
regardless of bus type, we can gleefully rip out this stop-gap, as
slight recompense for having to expand the other one.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index 607e709111731184c67a58bc039f583be446597f..fd8b9426f140d489fb8621452b7aa069869ff8e9 100644 (file)
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -804,57 +804,24 @@ struct iommu_dma_notifier_data {
 static LIST_HEAD(iommu_dma_masters);
 static DEFINE_MUTEX(iommu_dma_notifier_lock);
 
-/*
- * Temporarily "borrow" a domain feature flag to to tell if we had to resort
- * to creating our own domain here, in case we need to clean it up again.
- */
-#define __IOMMU_DOMAIN_FAKE_DEFAULT            (1U << 31)
-
 static bool do_iommu_attach(struct device *dev, const struct iommu_ops *ops,
                           u64 dma_base, u64 size)
 {
        struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
 
        /*
-        * Best case: The device is either part of a group which was
-        * already attached to a domain in a previous call, or it's
-        * been put in a default DMA domain by the IOMMU core.
+        * If the IOMMU driver has the DMA domain support that we require,
+        * then the IOMMU core will have already configured a group for this
+        * device, and allocated the default domain for that group.
         */
-       if (!domain) {
-               /*
-                * Urgh. The IOMMU core isn't going to do default domains
-                * for non-PCI devices anyway, until it has some means of
-                * abstracting the entirely implementation-specific
-                * sideband data/SoC topology/unicorn dust that may or
-                * may not differentiate upstream masters.
-                * So until then, HORRIBLE HACKS!
-                */
-               domain = ops->domain_alloc(IOMMU_DOMAIN_DMA);
-               if (!domain)
-                       goto out_no_domain;
-
-               domain->ops = ops;
-               domain->type = IOMMU_DOMAIN_DMA | __IOMMU_DOMAIN_FAKE_DEFAULT;
-
-               if (iommu_attach_device(domain, dev))
-                       goto out_put_domain;
+       if (!domain || iommu_dma_init_domain(domain, dma_base, size)) {
+               pr_warn("Failed to set up IOMMU for device %s; retaining platform DMA ops\n",
+                       dev_name(dev));
+               return false;
        }
 
-       if (iommu_dma_init_domain(domain, dma_base, size))
-               goto out_detach;
-
        dev->archdata.dma_ops = &iommu_dma_ops;
        return true;
-
-out_detach:
-       iommu_detach_device(domain, dev);
-out_put_domain:
-       if (domain->type & __IOMMU_DOMAIN_FAKE_DEFAULT)
-               iommu_domain_free(domain);
-out_no_domain:
-       pr_warn("Failed to set up IOMMU for device %s; retaining platform DMA ops\n",
-               dev_name(dev));
-       return false;
 }
 
 static void queue_iommu_attach(struct device *dev, const struct iommu_ops *ops,
@@ -971,11 +938,8 @@ void arch_teardown_dma_ops(struct device *dev)
 {
        struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
 
-       if (domain) {
+       if (WARN_ON(domain))
                iommu_detach_device(domain, dev);
-               if (domain->type & __IOMMU_DOMAIN_FAKE_DEFAULT)
-                       iommu_domain_free(domain);
-       }
 
        dev->archdata.dma_ops = NULL;
 }