[PATCH v4 3/4] arm64: Add IOMMU dma_ops
Robin Murphy
robin.murphy at arm.com
Thu Jul 16 11:40:14 PDT 2015
Taking some inspiration from the arch/arm code, implement the
arch-specific side of the DMA mapping ops using the new IOMMU-DMA layer.
Unfortunately the device setup code has to start out as a big ugly mess
in order to work usefully right now, as 'proper' operation depends on
changes to device probe and DMA configuration ordering, IOMMU groups for
platform devices, and default domain support in arm/arm64 IOMMU drivers.
The workarounds here need only exist until that work is finished.
Signed-off-by: Robin Murphy <robin.murphy at arm.com>
---
arch/arm64/mm/dma-mapping.c | 428 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 428 insertions(+)
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index d16a1ce..c89012e 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -526,3 +526,431 @@ static int __init dma_debug_do_init(void)
return 0;
}
fs_initcall(dma_debug_do_init);
+
+
+#ifdef CONFIG_IOMMU_DMA
+#include <linux/dma-iommu.h>
+#include <linux/platform_device.h>
+#include <linux/amba/bus.h>
+
+/* Thankfully, all cache ops are by VA so we can ignore phys here */
+static void flush_page(const void *virt, phys_addr_t phys)
+{
+ __dma_flush_range(virt, virt + PAGE_SIZE);
+}
+
+static void *__iommu_alloc_attrs(struct device *dev, size_t size,
+ dma_addr_t *handle, gfp_t gfp,
+ struct dma_attrs *attrs)
+{
+ bool coherent = is_device_dma_coherent(dev);
+ int ioprot = dma_direction_to_prot(DMA_BIDIRECTIONAL, coherent);
+ void *addr;
+
+ if (WARN(!dev, "cannot create IOMMU mapping for unknown device\n"))
+ return NULL;
+
+ /*
+ * Some drivers rely on this, and we may not want to potentially
+ * expose stale kernel data to devices anyway.
+ */
+ gfp |= __GFP_ZERO;
+
+ if (gfp & __GFP_WAIT) {
+ struct page **pages;
+ pgprot_t pgprot = coherent ? __pgprot(PROT_NORMAL) :
+ __pgprot(PROT_NORMAL_NC);
+
+ pgprot = __get_dma_pgprot(attrs, pgprot, coherent);
+ pages = iommu_dma_alloc(dev, size, gfp, ioprot, handle,
+ coherent ? NULL : flush_page);
+ if (!pages)
+ return NULL;
+
+ addr = dma_common_pages_remap(pages, size, VM_USERMAP, pgprot,
+ __builtin_return_address(0));
+ if (!addr)
+ iommu_dma_free(dev, pages, size, handle);
+ } else {
+ struct page *page;
+ /*
+ * In atomic context we can't remap anything, so we'll only
+ * get the virtually contiguous buffer we need by way of a
+ * physically contiguous allocation.
+ */
+ if (coherent) {
+ page = alloc_pages(gfp, get_order(size));
+ addr = page ? page_address(page) : NULL;
+ } else {
+ addr = __alloc_from_pool(size, &page, gfp);
+ }
+ if (!addr)
+ return NULL;
+
+ *handle = iommu_dma_map_page(dev, page, 0, size, ioprot);
+ if (iommu_dma_mapping_error(dev, *handle)) {
+ if (coherent)
+ __free_pages(page, get_order(size));
+ else
+ __free_from_pool(addr, size);
+ addr = NULL;
+ }
+ }
+ return addr;
+}
+
+static void __iommu_free_attrs(struct device *dev, size_t size, void *cpu_addr,
+ dma_addr_t handle, struct dma_attrs *attrs)
+{
+ /*
+ * @cpu_addr will be one of 3 things depending on how it was allocated:
+ * - A remapped array of pages from iommu_dma_alloc(), for all
+ * non-atomic allocations.
+ * - A non-cacheable alias from the atomic pool, for atomic
+ * allocations by non-coherent devices.
+ * - A normal lowmem address, for atomic allocations by
+ * coherent devices.
+ * Hence how dodgy the below logic looks...
+ */
+ if (__in_atomic_pool(cpu_addr, size)) {
+ iommu_dma_unmap_page(dev, handle, size, 0, NULL);
+ __free_from_pool(cpu_addr, size);
+ } else if (is_vmalloc_addr(cpu_addr)){
+ struct vm_struct *area = find_vm_area(cpu_addr);
+
+ if (WARN_ON(!area || !area->pages))
+ return;
+ iommu_dma_free(dev, area->pages, size, &handle);
+ dma_common_free_remap(cpu_addr, size, VM_USERMAP);
+ } else {
+ iommu_dma_unmap_page(dev, handle, size, 0, NULL);
+ __free_pages(virt_to_page(cpu_addr), get_order(size));
+ }
+}
+
+static int __iommu_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
+ void *cpu_addr, dma_addr_t dma_addr, size_t size,
+ struct dma_attrs *attrs)
+{
+ struct vm_struct *area;
+ int ret;
+
+ vma->vm_page_prot = __get_dma_pgprot(attrs, vma->vm_page_prot,
+ is_device_dma_coherent(dev));
+
+ if (dma_mmap_from_coherent(dev, vma, cpu_addr, size, &ret))
+ return ret;
+
+ area = find_vm_area(cpu_addr);
+ if (WARN_ON(!area || !area->pages))
+ return -ENXIO;
+
+ return iommu_dma_mmap(area->pages, size, vma);
+}
+
+static int __iommu_get_sgtable(struct device *dev, struct sg_table *sgt,
+ void *cpu_addr, dma_addr_t dma_addr,
+ size_t size, struct dma_attrs *attrs)
+{
+ unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+ struct vm_struct *area = find_vm_area(cpu_addr);
+
+ if (WARN_ON(!area || !area->pages))
+ return -ENXIO;
+
+ return sg_alloc_table_from_pages(sgt, area->pages, count, 0, size,
+ GFP_KERNEL);
+}
+
+static void __iommu_sync_single_for_cpu(struct device *dev,
+ dma_addr_t dev_addr, size_t size,
+ enum dma_data_direction dir)
+{
+ phys_addr_t phys;
+
+ if (is_device_dma_coherent(dev))
+ return;
+
+ phys = iommu_iova_to_phys(iommu_get_domain_for_dev(dev), dev_addr);
+ __dma_unmap_area(phys_to_virt(phys), size, dir);
+}
+
+static void __iommu_sync_single_for_device(struct device *dev,
+ dma_addr_t dev_addr, size_t size,
+ enum dma_data_direction dir)
+{
+ phys_addr_t phys;
+
+ if (is_device_dma_coherent(dev))
+ return;
+
+ phys = iommu_iova_to_phys(iommu_get_domain_for_dev(dev), dev_addr);
+ __dma_map_area(phys_to_virt(phys), size, dir);
+}
+
+static dma_addr_t __iommu_map_page(struct device *dev, struct page *page,
+ unsigned long offset, size_t size,
+ enum dma_data_direction dir,
+ struct dma_attrs *attrs)
+{
+ bool coherent = is_device_dma_coherent(dev);
+ int prot = dma_direction_to_prot(dir, coherent);
+ dma_addr_t dev_addr = iommu_dma_map_page(dev, page, offset, size, prot);
+
+ if (!iommu_dma_mapping_error(dev, dev_addr) &&
+ !dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs))
+ __iommu_sync_single_for_device(dev, dev_addr, size, dir);
+
+ return dev_addr;
+}
+
+static void __iommu_unmap_page(struct device *dev, dma_addr_t dev_addr,
+ size_t size, enum dma_data_direction dir,
+ struct dma_attrs *attrs)
+{
+ if (!dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs))
+ __iommu_sync_single_for_cpu(dev, dev_addr, size, dir);
+
+ iommu_dma_unmap_page(dev, dev_addr, size, dir, attrs);
+}
+
+static void __iommu_sync_sg_for_cpu(struct device *dev,
+ struct scatterlist *sgl, int nelems,
+ enum dma_data_direction dir)
+{
+ struct scatterlist *sg;
+ int i;
+
+ if (is_device_dma_coherent(dev))
+ return;
+
+ for_each_sg(sgl, sg, nelems, i)
+ __dma_unmap_area(sg_virt(sg), sg->length, dir);
+}
+
+static void __iommu_sync_sg_for_device(struct device *dev,
+ struct scatterlist *sgl, int nelems,
+ enum dma_data_direction dir)
+{
+ struct scatterlist *sg;
+ int i;
+
+ if (is_device_dma_coherent(dev))
+ return;
+
+ for_each_sg(sgl, sg, nelems, i)
+ __dma_map_area(sg_virt(sg), sg->length, dir);
+}
+
+static int __iommu_map_sg_attrs(struct device *dev, struct scatterlist *sgl,
+ int nelems, enum dma_data_direction dir,
+ struct dma_attrs *attrs)
+{
+ bool coherent = is_device_dma_coherent(dev);
+
+ if (!dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs))
+ __iommu_sync_sg_for_device(dev, sgl, nelems, dir);
+
+ return iommu_dma_map_sg(dev, sgl, nelems,
+ dma_direction_to_prot(dir, coherent));
+}
+
+static void __iommu_unmap_sg_attrs(struct device *dev,
+ struct scatterlist *sgl, int nelems,
+ enum dma_data_direction dir,
+ struct dma_attrs *attrs)
+{
+ if (!dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs))
+ __iommu_sync_sg_for_cpu(dev, sgl, nelems, dir);
+
+ iommu_dma_unmap_sg(dev, sgl, nelems, dir, attrs);
+}
+
+static struct dma_map_ops iommu_dma_ops = {
+ .alloc = __iommu_alloc_attrs,
+ .free = __iommu_free_attrs,
+ .mmap = __iommu_mmap_attrs,
+ .get_sgtable = __iommu_get_sgtable,
+ .map_page = __iommu_map_page,
+ .unmap_page = __iommu_unmap_page,
+ .map_sg = __iommu_map_sg_attrs,
+ .unmap_sg = __iommu_unmap_sg_attrs,
+ .sync_single_for_cpu = __iommu_sync_single_for_cpu,
+ .sync_single_for_device = __iommu_sync_single_for_device,
+ .sync_sg_for_cpu = __iommu_sync_sg_for_cpu,
+ .sync_sg_for_device = __iommu_sync_sg_for_device,
+ .dma_supported = iommu_dma_supported,
+ .mapping_error = iommu_dma_mapping_error,
+};
+
+/*
+ * 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);
+
+static int __iommu_attach_notifier(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ struct iommu_dma_notifier_data *master, *tmp;
+
+ if (action != BUS_NOTIFY_ADD_DEVICE)
+ return 0;
+ /*
+ * We expect the list to only contain the most recent addition
+ * (which should be the same device as in @data) so just process
+ * the whole thing blindly. If any previous attachments did happen
+ * to fail, they get a free retry since the domains are still live.
+ */
+ mutex_lock(&iommu_dma_notifier_lock);
+ list_for_each_entry_safe(master, tmp, &iommu_dma_masters, list) {
+ if (iommu_attach_device(master->dma_domain, master->dev)) {
+ pr_warn("Failed to attach device %s to IOMMU mapping; retaining platform DMA ops\n",
+ dev_name(master->dev));
+ } else {
+ master->dev->archdata.dma_ops = &iommu_dma_ops;
+ list_del(&master->list);
+ kfree(master);
+ }
+ }
+ mutex_unlock(&iommu_dma_notifier_lock);
+ return 0;
+}
+
+static int register_iommu_dma_ops_notifier(struct bus_type *bus)
+{
+ int ret;
+ struct notifier_block *nb = kzalloc(sizeof(*nb), GFP_KERNEL);
+
+ /*
+ * The device must be attached to a domain before the driver probe
+ * routine gets a chance to start allocating DMA buffers. However,
+ * the IOMMU driver also needs a chance to configure the iommu_group
+ * via its add_device callback first, so we need to make the attach
+ * happen between those two points. Since the IOMMU core uses a bus
+ * notifier with default priority for add_device, do the same but
+ * with a lower priority to ensure the appropriate ordering.
+ */
+ nb->notifier_call = __iommu_attach_notifier;
+ nb->priority = -100;
+
+ ret = bus_register_notifier(bus, nb);
+ if (ret) {
+ pr_warn("Failed to register DMA domain notifier; IOMMU DMA ops unavailable on bus '%s'\n",
+ bus->name);
+ kfree(nb);
+ }
+ return ret;
+}
+
+static int queue_iommu_attach(struct iommu_domain *domain, struct device *dev)
+{
+ struct iommu_dma_notifier_data *iommudata = NULL;
+
+ iommudata = kzalloc(sizeof(*iommudata), GFP_KERNEL);
+ if (!iommudata)
+ return -ENOMEM;
+
+ iommudata->dev = dev;
+ iommudata->dma_domain = domain;
+
+ mutex_lock(&iommu_dma_notifier_lock);
+ list_add(&iommudata->list, &iommu_dma_masters);
+ mutex_unlock(&iommu_dma_notifier_lock);
+ return 0;
+}
+
+static int __init arm64_iommu_dma_init(void)
+{
+ int ret;
+
+ ret = iommu_dma_init();
+ if (!ret)
+ ret = register_iommu_dma_ops_notifier(&platform_bus_type);
+ if (!ret)
+ ret = register_iommu_dma_ops_notifier(&amba_bustype);
+ return ret;
+}
+arch_initcall(arm64_iommu_dma_init);
+
+/* Hijack some domain feature flags for the stop-gap meddling below */
+#define __IOMMU_DOMAIN_ARM64 (1U << 31)
+#define __IOMMU_DOMAIN_ARM64_IOVA (1U << 30)
+
+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!
+ */
+ domain = ops->domain_alloc(IOMMU_DOMAIN_DMA);
+ if (!domain)
+ domain = ops->domain_alloc(IOMMU_DOMAIN_UNMANAGED);
+ if (!domain)
+ goto out_no_domain;
+
+ domain->ops = ops;
+ domain->type = IOMMU_DOMAIN_DMA | __IOMMU_DOMAIN_ARM64;
+ if (!domain->dma_api_cookie) {
+ domain->type |= __IOMMU_DOMAIN_ARM64_IOVA;
+ if (iommu_get_dma_cookie(domain))
+ goto out_put_domain;
+ }
+ }
+
+ if (iommu_dma_init_domain(domain, dma_base, size)) {
+ pr_warn("Failed to create %llu-byte IOMMU mapping for device %s\n",
+ size, dev_name(dev));
+ goto out_put_domain;
+ }
+
+ if (dev->iommu_group)
+ err = iommu_attach_device(domain, dev);
+ else
+ err = queue_iommu_attach(domain, dev);
+
+ if (!err) {
+ dev->archdata.dma_ops = &iommu_dma_ops;
+ return;
+ }
+
+out_put_domain:
+ if (domain->type & __IOMMU_DOMAIN_ARM64_IOVA)
+ iommu_put_dma_cookie(domain);
+ if (domain->type & __IOMMU_DOMAIN_ARM64)
+ ops->domain_free(domain);
+out_no_domain:
+ pr_warn("Failed to set up IOMMU domain for device %s\n", dev_name(dev));
+}
+
+#else
+
+static void __iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
+ struct iommu_ops *iommu)
+{ }
+
+#endif /* CONFIG_IOMMU_DMA */
--
1.9.1
More information about the linux-arm-kernel
mailing list