On Fri, Jul 31, 2015 at 06:18:28PM +0100, Robin Murphy wrote:

+/*
+ * TODO: Right now __iommu_setup_dma_ops() gets called too early to do
+ * everything it needs to - the device isn't yet fully created, and the
+ * IOMMU driver hasn't seen it yet, so we need this delayed attachment
+ * dance. Once IOMMU probe ordering is sorted to move the
+ * arch_setup_dma_ops() call later, all the notifier bits below become
+ * unnecessary, and will go away.
+ */
+struct iommu_dma_notifier_data {
+	struct list_head list;
+	struct device *dev;
+	struct iommu_domain *dma_domain;
+};
+static LIST_HEAD(iommu_dma_masters);
+static DEFINE_MUTEX(iommu_dma_notifier_lock);

Ugh, thats incredibly ugly. Why can't you do the setup work then the
iommu driver sees the device? Just call the dma-api setup functions
there (like the x86 iommu drivers do it too) and be done without any
notifiers.

+static void __iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
+				  const struct iommu_ops *ops)
+{
+	struct iommu_domain *domain;
+	int err;
+
+	if (!ops)
+		return;
+	/*
+	 * In a perfect world, everything happened in the right order up to
+	 * here, and the IOMMU core has already attached the device to an
+	 * appropriate default domain for us to set up...
+	 */
+	domain = iommu_get_domain_for_dev(dev);
+	if (!domain) {
+		/*
+		 * Urgh. Reliable default domains for platform devices can't
+		 * happen anyway without some sensible way of handling
+		 * non-trivial groups. So until then, HORRIBLE HACKS!
+		 */

I don't get this, what is preventing to rely on default domains here?

+		domain = ops->domain_alloc(IOMMU_DOMAIN_DMA);

The IOMMU core should already tried to allocate an IOMMU_DOMAIN_DMA type
domain. No need to try this again here.



	Joerg