Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1288 insertions, 0 deletions

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
new file mode 100644
index 000000000..d1539b739
--- /dev/null
+++ b/drivers/iommu/dma-iommu.c
@@ -0,0 +1,1288 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * A fairly generic DMA-API to IOMMU-API glue layer.
+ *
+ * Copyright (C) 2014-2015 ARM Ltd.
+ *
+ * based in part on arch/arm/mm/dma-mapping.c:
+ * Copyright (C) 2000-2004 Russell King
+ */
+
+#include <linux/acpi_iort.h>
+#include <linux/device.h>
+#include <linux/dma-map-ops.h>
+#include <linux/dma-iommu.h>
+#include <linux/gfp.h>
+#include <linux/huge_mm.h>
+#include <linux/iommu.h>
+#include <linux/iova.h>
+#include <linux/irq.h>
+#include <linux/mm.h>
+#include <linux/mutex.h>
+#include <linux/pci.h>
+#include <linux/scatterlist.h>
+#include <linux/vmalloc.h>
+#include <linux/crash_dump.h>
+
+struct iommu_dma_msi_page {
+	struct list_head	list;
+	dma_addr_t		iova;
+	phys_addr_t		phys;
+};
+
+enum iommu_dma_cookie_type {
+	IOMMU_DMA_IOVA_COOKIE,
+	IOMMU_DMA_MSI_COOKIE,
+};
+
+struct iommu_dma_cookie {
+	enum iommu_dma_cookie_type	type;
+	union {
+		/* Full allocator for IOMMU_DMA_IOVA_COOKIE */
+		struct iova_domain	iovad;
+		/* Trivial linear page allocator for IOMMU_DMA_MSI_COOKIE */
+		dma_addr_t		msi_iova;
+	};
+	struct list_head		msi_page_list;
+
+	/* Domain for flush queue callback; NULL if flush queue not in use */
+	struct iommu_domain		*fq_domain;
+};
+
+static inline size_t cookie_msi_granule(struct iommu_dma_cookie *cookie)
+{
+	if (cookie->type == IOMMU_DMA_IOVA_COOKIE)
+		return cookie->iovad.granule;
+	return PAGE_SIZE;
+}
+
+static struct iommu_dma_cookie *cookie_alloc(enum iommu_dma_cookie_type type)
+{
+	struct iommu_dma_cookie *cookie;
+
+	cookie = kzalloc(sizeof(*cookie), GFP_KERNEL);
+	if (cookie) {
+		INIT_LIST_HEAD(&cookie->msi_page_list);
+		cookie->type = type;
+	}
+	return cookie;
+}
+
+/**
+ * iommu_get_dma_cookie - Acquire DMA-API resources for a domain
+ * @domain: IOMMU domain to prepare for DMA-API usage
+ *
+ * IOMMU drivers should normally call this from their domain_alloc
+ * callback when domain->type == IOMMU_DOMAIN_DMA.
+ */
+int iommu_get_dma_cookie(struct iommu_domain *domain)
+{
+	if (domain->iova_cookie)
+		return -EEXIST;
+
+	domain->iova_cookie = cookie_alloc(IOMMU_DMA_IOVA_COOKIE);
+	if (!domain->iova_cookie)
+		return -ENOMEM;
+
+	return 0;
+}
+EXPORT_SYMBOL(iommu_get_dma_cookie);
+
+/**
+ * iommu_get_msi_cookie - Acquire just MSI remapping resources
+ * @domain: IOMMU domain to prepare
+ * @base: Start address of IOVA region for MSI mappings
+ *
+ * Users who manage their own IOVA allocation and do not want DMA API support,
+ * but would still like to take advantage of automatic MSI remapping, can use
+ * this to initialise their own domain appropriately. Users should reserve a
+ * contiguous IOVA region, starting at @base, large enough to accommodate the
+ * number of PAGE_SIZE mappings necessary to cover every MSI doorbell address
+ * used by the devices attached to @domain.
+ */
+int iommu_get_msi_cookie(struct iommu_domain *domain, dma_addr_t base)
+{
+	struct iommu_dma_cookie *cookie;
+
+	if (domain->type != IOMMU_DOMAIN_UNMANAGED)
+		return -EINVAL;
+
+	if (domain->iova_cookie)
+		return -EEXIST;
+
+	cookie = cookie_alloc(IOMMU_DMA_MSI_COOKIE);
+	if (!cookie)
+		return -ENOMEM;
+
+	cookie->msi_iova = base;
+	domain->iova_cookie = cookie;
+	return 0;
+}
+EXPORT_SYMBOL(iommu_get_msi_cookie);
+
+/**
+ * iommu_put_dma_cookie - Release a domain's DMA mapping resources
+ * @domain: IOMMU domain previously prepared by iommu_get_dma_cookie() or
+ *          iommu_get_msi_cookie()
+ *
+ * IOMMU drivers should normally call this from their domain_free callback.
+ */
+void iommu_put_dma_cookie(struct iommu_domain *domain)
+{
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	struct iommu_dma_msi_page *msi, *tmp;
+
+	if (!cookie)
+		return;
+
+	if (cookie->type == IOMMU_DMA_IOVA_COOKIE && cookie->iovad.granule)
+		put_iova_domain(&cookie->iovad);
+
+	list_for_each_entry_safe(msi, tmp, &cookie->msi_page_list, list) {
+		list_del(&msi->list);
+		kfree(msi);
+	}
+	kfree(cookie);
+	domain->iova_cookie = NULL;
+}
+EXPORT_SYMBOL(iommu_put_dma_cookie);
+
+/**
+ * iommu_dma_get_resv_regions - Reserved region driver helper
+ * @dev: Device from iommu_get_resv_regions()
+ * @list: Reserved region list from iommu_get_resv_regions()
+ *
+ * IOMMU drivers can use this to implement their .get_resv_regions callback
+ * for general non-IOMMU-specific reservations. Currently, this covers GICv3
+ * ITS region reservation on ACPI based ARM platforms that may require HW MSI
+ * reservation.
+ */
+void iommu_dma_get_resv_regions(struct device *dev, struct list_head *list)
+{
+
+	if (!is_of_node(dev_iommu_fwspec_get(dev)->iommu_fwnode))
+		iort_iommu_msi_get_resv_regions(dev, list);
+
+}
+EXPORT_SYMBOL(iommu_dma_get_resv_regions);
+
+static int cookie_init_hw_msi_region(struct iommu_dma_cookie *cookie,
+		phys_addr_t start, phys_addr_t end)
+{
+	struct iova_domain *iovad = &cookie->iovad;
+	struct iommu_dma_msi_page *msi_page;
+	int i, num_pages;
+
+	start -= iova_offset(iovad, start);
+	num_pages = iova_align(iovad, end - start) >> iova_shift(iovad);
+
+	for (i = 0; i < num_pages; i++) {
+		msi_page = kmalloc(sizeof(*msi_page), GFP_KERNEL);
+		if (!msi_page)
+			return -ENOMEM;
+
+		msi_page->phys = start;
+		msi_page->iova = start;
+		INIT_LIST_HEAD(&msi_page->list);
+		list_add(&msi_page->list, &cookie->msi_page_list);
+		start += iovad->granule;
+	}
+
+	return 0;
+}
+
+static int iova_reserve_pci_windows(struct pci_dev *dev,
+		struct iova_domain *iovad)
+{
+	struct pci_host_bridge *bridge = pci_find_host_bridge(dev->bus);
+	struct resource_entry *window;
+	unsigned long lo, hi;
+	phys_addr_t start = 0, end;
+
+	resource_list_for_each_entry(window, &bridge->windows) {
+		if (resource_type(window->res) != IORESOURCE_MEM)
+			continue;
+
+		lo = iova_pfn(iovad, window->res->start - window->offset);
+		hi = iova_pfn(iovad, window->res->end - window->offset);
+		reserve_iova(iovad, lo, hi);
+	}
+
+	/* Get reserved DMA windows from host bridge */
+	resource_list_for_each_entry(window, &bridge->dma_ranges) {
+		end = window->res->start - window->offset;
+resv_iova:
+		if (end > start) {
+			lo = iova_pfn(iovad, start);
+			hi = iova_pfn(iovad, end);
+			reserve_iova(iovad, lo, hi);
+		} else if (end < start) {
+			/* dma_ranges list should be sorted */
+			dev_err(&dev->dev,
+				"Failed to reserve IOVA [%pa-%pa]\n",
+				&start, &end);
+			return -EINVAL;
+		}
+
+		start = window->res->end - window->offset + 1;
+		/* If window is last entry */
+		if (window->node.next == &bridge->dma_ranges &&
+		    end != ~(phys_addr_t)0) {
+			end = ~(phys_addr_t)0;
+			goto resv_iova;
+		}
+	}
+
+	return 0;
+}
+
+static int iova_reserve_iommu_regions(struct device *dev,
+		struct iommu_domain *domain)
+{
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	struct iova_domain *iovad = &cookie->iovad;
+	struct iommu_resv_region *region;
+	LIST_HEAD(resv_regions);
+	int ret = 0;
+
+	if (dev_is_pci(dev)) {
+		ret = iova_reserve_pci_windows(to_pci_dev(dev), iovad);
+		if (ret)
+			return ret;
+	}
+
+	iommu_get_resv_regions(dev, &resv_regions);
+	list_for_each_entry(region, &resv_regions, list) {
+		unsigned long lo, hi;
+
+		/* We ARE the software that manages these! */
+		if (region->type == IOMMU_RESV_SW_MSI)
+			continue;
+
+		lo = iova_pfn(iovad, region->start);
+		hi = iova_pfn(iovad, region->start + region->length - 1);
+		reserve_iova(iovad, lo, hi);
+
+		if (region->type == IOMMU_RESV_MSI)
+			ret = cookie_init_hw_msi_region(cookie, region->start,
+					region->start + region->length);
+		if (ret)
+			break;
+	}
+	iommu_put_resv_regions(dev, &resv_regions);
+
+	return ret;
+}
+
+static void iommu_dma_flush_iotlb_all(struct iova_domain *iovad)
+{
+	struct iommu_dma_cookie *cookie;
+	struct iommu_domain *domain;
+
+	cookie = container_of(iovad, struct iommu_dma_cookie, iovad);
+	domain = cookie->fq_domain;
+	/*
+	 * The IOMMU driver supporting DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE
+	 * implies that ops->flush_iotlb_all must be non-NULL.
+	 */
+	domain->ops->flush_iotlb_all(domain);
+}
+
+/**
+ * iommu_dma_init_domain - Initialise a DMA mapping domain
+ * @domain: IOMMU domain previously prepared by iommu_get_dma_cookie()
+ * @base: IOVA at which the mappable address space starts
+ * @size: Size of IOVA space
+ * @dev: Device the domain is being initialised for
+ *
+ * @base and @size should be exact multiples of IOMMU page granularity to
+ * avoid rounding surprises. If necessary, we reserve the page at address 0
+ * to ensure it is an invalid IOVA. It is safe to reinitialise a domain, but
+ * any change which could make prior IOVAs invalid will fail.
+ */
+static int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base,
+		u64 size, struct device *dev)
+{
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	unsigned long order, base_pfn;
+	struct iova_domain *iovad;
+	int attr;
+
+	if (!cookie || cookie->type != IOMMU_DMA_IOVA_COOKIE)
+		return -EINVAL;
+
+	iovad = &cookie->iovad;
+
+	/* Use the smallest supported page size for IOVA granularity */
+	order = __ffs(domain->pgsize_bitmap);
+	base_pfn = max_t(unsigned long, 1, base >> order);
+
+	/* Check the domain allows at least some access to the device... */
+	if (domain->geometry.force_aperture) {
+		if (base > domain->geometry.aperture_end ||
+		    base + size <= domain->geometry.aperture_start) {
+			pr_warn("specified DMA range outside IOMMU capability\n");
+			return -EFAULT;
+		}
+		/* ...then finally give it a kicking to make sure it fits */
+		base_pfn = max_t(unsigned long, base_pfn,
+				domain->geometry.aperture_start >> order);
+	}
+
+	/* start_pfn is always nonzero for an already-initialised domain */
+	if (iovad->start_pfn) {
+		if (1UL << order != iovad->granule ||
+		    base_pfn != iovad->start_pfn) {
+			pr_warn("Incompatible range for DMA domain\n");
+			return -EFAULT;
+		}
+
+		return 0;
+	}
+
+	init_iova_domain(iovad, 1UL << order, base_pfn);
+
+	if (!cookie->fq_domain && !iommu_domain_get_attr(domain,
+			DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE, &attr) && attr) {
+		if (init_iova_flush_queue(iovad, iommu_dma_flush_iotlb_all,
+					NULL))
+			pr_warn("iova flush queue initialization failed\n");
+		else
+			cookie->fq_domain = domain;
+	}
+
+	if (!dev)
+		return 0;
+
+	return iova_reserve_iommu_regions(dev, domain);
+}
+
+static int iommu_dma_deferred_attach(struct device *dev,
+		struct iommu_domain *domain)
+{
+	const struct iommu_ops *ops = domain->ops;
+
+	if (!is_kdump_kernel())
+		return 0;
+
+	if (unlikely(ops->is_attach_deferred &&
+			ops->is_attach_deferred(domain, dev)))
+		return iommu_attach_device(domain, dev);
+
+	return 0;
+}
+
+/**
+ * dma_info_to_prot - Translate DMA API directions and attributes to IOMMU API
+ *                    page flags.
+ * @dir: Direction of DMA transfer
+ * @coherent: Is the DMA master cache-coherent?
+ * @attrs: DMA attributes for the mapping
+ *
+ * Return: corresponding IOMMU API page protection flags
+ */
+static int dma_info_to_prot(enum dma_data_direction dir, bool coherent,
+		     unsigned long attrs)
+{
+	int prot = coherent ? IOMMU_CACHE : 0;
+
+	if (attrs & DMA_ATTR_PRIVILEGED)
+		prot |= IOMMU_PRIV;
+
+	switch (dir) {
+	case DMA_BIDIRECTIONAL:
+		return prot | IOMMU_READ | IOMMU_WRITE;
+	case DMA_TO_DEVICE:
+		return prot | IOMMU_READ;
+	case DMA_FROM_DEVICE:
+		return prot | IOMMU_WRITE;
+	default:
+		return 0;
+	}
+}
+
+static dma_addr_t iommu_dma_alloc_iova(struct iommu_domain *domain,
+		size_t size, u64 dma_limit, struct device *dev)
+{
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	struct iova_domain *iovad = &cookie->iovad;
+	unsigned long shift, iova_len, iova = 0;
+
+	if (cookie->type == IOMMU_DMA_MSI_COOKIE) {
+		cookie->msi_iova += size;
+		return cookie->msi_iova - size;
+	}
+
+	shift = iova_shift(iovad);
+	iova_len = size >> shift;
+	/*
+	 * Freeing non-power-of-two-sized allocations back into the IOVA caches
+	 * will come back to bite us badly, so we have to waste a bit of space
+	 * rounding up anything cacheable to make sure that can't happen. The
+	 * order of the unadjusted size will still match upon freeing.
+	 */
+	if (iova_len < (1 << (IOVA_RANGE_CACHE_MAX_SIZE - 1)))
+		iova_len = roundup_pow_of_two(iova_len);
+
+	dma_limit = min_not_zero(dma_limit, dev->bus_dma_limit);
+
+	if (domain->geometry.force_aperture)
+		dma_limit = min(dma_limit, (u64)domain->geometry.aperture_end);
+
+	/* Try to get PCI devices a SAC address */
+	if (dma_limit > DMA_BIT_MASK(32) && dev_is_pci(dev))
+		iova = alloc_iova_fast(iovad, iova_len,
+				       DMA_BIT_MASK(32) >> shift, false);
+
+	if (!iova)
+		iova = alloc_iova_fast(iovad, iova_len, dma_limit >> shift,
+				       true);
+
+	return (dma_addr_t)iova << shift;
+}
+
+static void iommu_dma_free_iova(struct iommu_dma_cookie *cookie,
+		dma_addr_t iova, size_t size)
+{
+	struct iova_domain *iovad = &cookie->iovad;
+
+	/* The MSI case is only ever cleaning up its most recent allocation */
+	if (cookie->type == IOMMU_DMA_MSI_COOKIE)
+		cookie->msi_iova -= size;
+	else if (cookie->fq_domain)	/* non-strict mode */
+		queue_iova(iovad, iova_pfn(iovad, iova),
+				size >> iova_shift(iovad), 0);
+	else
+		free_iova_fast(iovad, iova_pfn(iovad, iova),
+				size >> iova_shift(iovad));
+}
+
+static void __iommu_dma_unmap(struct device *dev, dma_addr_t dma_addr,
+		size_t size)
+{
+	struct iommu_domain *domain = iommu_get_dma_domain(dev);
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	struct iova_domain *iovad = &cookie->iovad;
+	size_t iova_off = iova_offset(iovad, dma_addr);
+	struct iommu_iotlb_gather iotlb_gather;
+	size_t unmapped;
+
+	dma_addr -= iova_off;
+	size = iova_align(iovad, size + iova_off);
+	iommu_iotlb_gather_init(&iotlb_gather);
+
+	unmapped = iommu_unmap_fast(domain, dma_addr, size, &iotlb_gather);
+	WARN_ON(unmapped != size);
+
+	if (!cookie->fq_domain)
+		iommu_iotlb_sync(domain, &iotlb_gather);
+	iommu_dma_free_iova(cookie, dma_addr, size);
+}
+
+static dma_addr_t __iommu_dma_map(struct device *dev, phys_addr_t phys,
+		size_t size, int prot, u64 dma_mask)
+{
+	struct iommu_domain *domain = iommu_get_dma_domain(dev);
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	struct iova_domain *iovad = &cookie->iovad;
+	size_t iova_off = iova_offset(iovad, phys);
+	dma_addr_t iova;
+
+	if (unlikely(iommu_dma_deferred_attach(dev, domain)))
+		return DMA_MAPPING_ERROR;
+
+	size = iova_align(iovad, size + iova_off);
+
+	iova = iommu_dma_alloc_iova(domain, size, dma_mask, dev);
+	if (!iova)
+		return DMA_MAPPING_ERROR;
+
+	if (iommu_map_atomic(domain, iova, phys - iova_off, size, prot)) {
+		iommu_dma_free_iova(cookie, iova, size);
+		return DMA_MAPPING_ERROR;
+	}
+	return iova + iova_off;
+}
+
+static void __iommu_dma_free_pages(struct page **pages, int count)
+{
+	while (count--)
+		__free_page(pages[count]);
+	kvfree(pages);
+}
+
+static struct page **__iommu_dma_alloc_pages(struct device *dev,
+		unsigned int count, unsigned long order_mask, gfp_t gfp)
+{
+	struct page **pages;
+	unsigned int i = 0, nid = dev_to_node(dev);
+
+	order_mask &= (2U << MAX_ORDER) - 1;
+	if (!order_mask)
+		return NULL;
+
+	pages = kvzalloc(count * sizeof(*pages), GFP_KERNEL);
+	if (!pages)
+		return NULL;
+
+	/* IOMMU can map any pages, so himem can also be used here */
+	gfp |= __GFP_NOWARN | __GFP_HIGHMEM;
+
+	/* It makes no sense to muck about with huge pages */
+	gfp &= ~__GFP_COMP;
+
+	while (count) {
+		struct page *page = NULL;
+		unsigned int order_size;
+
+		/*
+		 * Higher-order allocations are a convenience rather
+		 * than a necessity, hence using __GFP_NORETRY until
+		 * falling back to minimum-order allocations.
+		 */
+		for (order_mask &= (2U << __fls(count)) - 1;
+		     order_mask; order_mask &= ~order_size) {
+			unsigned int order = __fls(order_mask);
+			gfp_t alloc_flags = gfp;
+
+			order_size = 1U << order;
+			if (order_mask > order_size)
+				alloc_flags |= __GFP_NORETRY;
+			page = alloc_pages_node(nid, alloc_flags, order);
+			if (!page)
+				continue;
+			if (order)
+				split_page(page, order);
+			break;
+		}
+		if (!page) {
+			__iommu_dma_free_pages(pages, i);
+			return NULL;
+		}
+		count -= order_size;
+		while (order_size--)
+			pages[i++] = page++;
+	}
+	return pages;
+}
+
+/**
+ * iommu_dma_alloc_remap - Allocate and map a buffer contiguous in IOVA space
+ * @dev: Device to allocate memory for. Must be a real device
+ *	 attached to an iommu_dma_domain
+ * @size: Size of buffer in bytes
+ * @dma_handle: Out argument for allocated DMA handle
+ * @gfp: Allocation flags
+ * @prot: pgprot_t to use for the remapped mapping
+ * @attrs: DMA attributes for this allocation
+ *
+ * If @size is less than PAGE_SIZE, then a full CPU page will be allocated,
+ * but an IOMMU which supports smaller pages might not map the whole thing.
+ *
+ * Return: Mapped virtual address, or NULL on failure.
+ */
+static void *iommu_dma_alloc_remap(struct device *dev, size_t size,
+		dma_addr_t *dma_handle, gfp_t gfp, pgprot_t prot,
+		unsigned long attrs)
+{
+	struct iommu_domain *domain = iommu_get_dma_domain(dev);
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	struct iova_domain *iovad = &cookie->iovad;
+	bool coherent = dev_is_dma_coherent(dev);
+	int ioprot = dma_info_to_prot(DMA_BIDIRECTIONAL, coherent, attrs);
+	unsigned int count, min_size, alloc_sizes = domain->pgsize_bitmap;
+	struct page **pages;
+	struct sg_table sgt;
+	dma_addr_t iova;
+	void *vaddr;
+
+	*dma_handle = DMA_MAPPING_ERROR;
+
+	if (unlikely(iommu_dma_deferred_attach(dev, domain)))
+		return NULL;
+
+	min_size = alloc_sizes & -alloc_sizes;
+	if (min_size < PAGE_SIZE) {
+		min_size = PAGE_SIZE;
+		alloc_sizes |= PAGE_SIZE;
+	} else {
+		size = ALIGN(size, min_size);
+	}
+	if (attrs & DMA_ATTR_ALLOC_SINGLE_PAGES)
+		alloc_sizes = min_size;
+
+	count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+	pages = __iommu_dma_alloc_pages(dev, count, alloc_sizes >> PAGE_SHIFT,
+					gfp);
+	if (!pages)
+		return NULL;
+
+	size = iova_align(iovad, size);
+	iova = iommu_dma_alloc_iova(domain, size, dev->coherent_dma_mask, dev);
+	if (!iova)
+		goto out_free_pages;
+
+	if (sg_alloc_table_from_pages(&sgt, pages, count, 0, size, GFP_KERNEL))
+		goto out_free_iova;
+
+	if (!(ioprot & IOMMU_CACHE)) {
+		struct scatterlist *sg;
+		int i;
+
+		for_each_sg(sgt.sgl, sg, sgt.orig_nents, i)
+			arch_dma_prep_coherent(sg_page(sg), sg->length);
+	}
+
+	if (iommu_map_sg_atomic(domain, iova, sgt.sgl, sgt.orig_nents, ioprot)
+			< size)
+		goto out_free_sg;
+
+	vaddr = dma_common_pages_remap(pages, size, prot,
+			__builtin_return_address(0));
+	if (!vaddr)
+		goto out_unmap;
+
+	*dma_handle = iova;
+	sg_free_table(&sgt);
+	return vaddr;
+
+out_unmap:
+	__iommu_dma_unmap(dev, iova, size);
+out_free_sg:
+	sg_free_table(&sgt);
+out_free_iova:
+	iommu_dma_free_iova(cookie, iova, size);
+out_free_pages:
+	__iommu_dma_free_pages(pages, count);
+	return NULL;
+}
+
+/**
+ * __iommu_dma_mmap - Map a buffer into provided user VMA
+ * @pages: Array representing buffer from __iommu_dma_alloc()
+ * @size: Size of buffer in bytes
+ * @vma: VMA describing requested userspace mapping
+ *
+ * Maps the pages of the buffer in @pages into @vma. The caller is responsible
+ * for verifying the correct size and protection of @vma beforehand.
+ */
+static int __iommu_dma_mmap(struct page **pages, size_t size,
+		struct vm_area_struct *vma)
+{
+	return vm_map_pages(vma, pages, PAGE_ALIGN(size) >> PAGE_SHIFT);
+}
+
+static void iommu_dma_sync_single_for_cpu(struct device *dev,
+		dma_addr_t dma_handle, size_t size, enum dma_data_direction dir)
+{
+	phys_addr_t phys;
+
+	if (dev_is_dma_coherent(dev))
+		return;
+
+	phys = iommu_iova_to_phys(iommu_get_dma_domain(dev), dma_handle);
+	arch_sync_dma_for_cpu(phys, size, dir);
+}
+
+static void iommu_dma_sync_single_for_device(struct device *dev,
+		dma_addr_t dma_handle, size_t size, enum dma_data_direction dir)
+{
+	phys_addr_t phys;
+
+	if (dev_is_dma_coherent(dev))
+		return;
+
+	phys = iommu_iova_to_phys(iommu_get_dma_domain(dev), dma_handle);
+	arch_sync_dma_for_device(phys, size, dir);
+}
+
+static void iommu_dma_sync_sg_for_cpu(struct device *dev,
+		struct scatterlist *sgl, int nelems,
+		enum dma_data_direction dir)
+{
+	struct scatterlist *sg;
+	int i;
+
+	if (dev_is_dma_coherent(dev))
+		return;
+
+	for_each_sg(sgl, sg, nelems, i)
+		arch_sync_dma_for_cpu(sg_phys(sg), sg->length, dir);
+}
+
+static void iommu_dma_sync_sg_for_device(struct device *dev,
+		struct scatterlist *sgl, int nelems,
+		enum dma_data_direction dir)
+{
+	struct scatterlist *sg;
+	int i;
+
+	if (dev_is_dma_coherent(dev))
+		return;
+
+	for_each_sg(sgl, sg, nelems, i)
+		arch_sync_dma_for_device(sg_phys(sg), sg->length, dir);
+}
+
+static dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
+		unsigned long offset, size_t size, enum dma_data_direction dir,
+		unsigned long attrs)
+{
+	phys_addr_t phys = page_to_phys(page) + offset;
+	bool coherent = dev_is_dma_coherent(dev);
+	int prot = dma_info_to_prot(dir, coherent, attrs);
+	dma_addr_t dma_handle;
+
+	dma_handle = __iommu_dma_map(dev, phys, size, prot, dma_get_mask(dev));
+	if (!coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
+	    dma_handle != DMA_MAPPING_ERROR)
+		arch_sync_dma_for_device(phys, size, dir);
+	return dma_handle;
+}
+
+static void iommu_dma_unmap_page(struct device *dev, dma_addr_t dma_handle,
+		size_t size, enum dma_data_direction dir, unsigned long attrs)
+{
+	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		iommu_dma_sync_single_for_cpu(dev, dma_handle, size, dir);
+	__iommu_dma_unmap(dev, dma_handle, size);
+}
+
+/*
+ * Prepare a successfully-mapped scatterlist to give back to the caller.
+ *
+ * At this point the segments are already laid out by iommu_dma_map_sg() to
+ * avoid individually crossing any boundaries, so we merely need to check a
+ * segment's start address to avoid concatenating across one.
+ */
+static int __finalise_sg(struct device *dev, struct scatterlist *sg, int nents,
+		dma_addr_t dma_addr)
+{
+	struct scatterlist *s, *cur = sg;
+	unsigned long seg_mask = dma_get_seg_boundary(dev);
+	unsigned int cur_len = 0, max_len = dma_get_max_seg_size(dev);
+	int i, count = 0;
+
+	for_each_sg(sg, s, nents, i) {
+		/* Restore this segment's original unaligned fields first */
+		unsigned int s_iova_off = sg_dma_address(s);
+		unsigned int s_length = sg_dma_len(s);
+		unsigned int s_iova_len = s->length;
+
+		s->offset += s_iova_off;
+		s->length = s_length;
+		sg_dma_address(s) = DMA_MAPPING_ERROR;
+		sg_dma_len(s) = 0;
+
+		/*
+		 * Now fill in the real DMA data. If...
+		 * - there is a valid output segment to append to
+		 * - and this segment starts on an IOVA page boundary
+		 * - but doesn't fall at a segment boundary
+		 * - and wouldn't make the resulting output segment too long
+		 */
+		if (cur_len && !s_iova_off && (dma_addr & seg_mask) &&
+		    (max_len - cur_len >= s_length)) {
+			/* ...then concatenate it with the previous one */
+			cur_len += s_length;
+		} else {
+			/* Otherwise start the next output segment */
+			if (i > 0)
+				cur = sg_next(cur);
+			cur_len = s_length;
+			count++;
+
+			sg_dma_address(cur) = dma_addr + s_iova_off;
+		}
+
+		sg_dma_len(cur) = cur_len;
+		dma_addr += s_iova_len;
+
+		if (s_length + s_iova_off < s_iova_len)
+			cur_len = 0;
+	}
+	return count;
+}
+
+/*
+ * If mapping failed, then just restore the original list,
+ * but making sure the DMA fields are invalidated.
+ */
+static void __invalidate_sg(struct scatterlist *sg, int nents)
+{
+	struct scatterlist *s;
+	int i;
+
+	for_each_sg(sg, s, nents, i) {
+		if (sg_dma_address(s) != DMA_MAPPING_ERROR)
+			s->offset += sg_dma_address(s);
+		if (sg_dma_len(s))
+			s->length = sg_dma_len(s);
+		sg_dma_address(s) = DMA_MAPPING_ERROR;
+		sg_dma_len(s) = 0;
+	}
+}
+
+/*
+ * The DMA API client is passing in a scatterlist which could describe
+ * any old buffer layout, but the IOMMU API requires everything to be
+ * aligned to IOMMU pages. Hence the need for this complicated bit of
+ * impedance-matching, to be able to hand off a suitably-aligned list,
+ * but still preserve the original offsets and sizes for the caller.
+ */
+static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
+		int nents, enum dma_data_direction dir, unsigned long attrs)
+{
+	struct iommu_domain *domain = iommu_get_dma_domain(dev);
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	struct iova_domain *iovad = &cookie->iovad;
+	struct scatterlist *s, *prev = NULL;
+	int prot = dma_info_to_prot(dir, dev_is_dma_coherent(dev), attrs);
+	dma_addr_t iova;
+	size_t iova_len = 0;
+	unsigned long mask = dma_get_seg_boundary(dev);
+	int i;
+
+	if (unlikely(iommu_dma_deferred_attach(dev, domain)))
+		return 0;
+
+	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		iommu_dma_sync_sg_for_device(dev, sg, nents, dir);
+
+	/*
+	 * Work out how much IOVA space we need, and align the segments to
+	 * IOVA granules for the IOMMU driver to handle. With some clever
+	 * trickery we can modify the list in-place, but reversibly, by
+	 * stashing the unaligned parts in the as-yet-unused DMA fields.
+	 */
+	for_each_sg(sg, s, nents, i) {
+		size_t s_iova_off = iova_offset(iovad, s->offset);
+		size_t s_length = s->length;
+		size_t pad_len = (mask - iova_len + 1) & mask;
+
+		sg_dma_address(s) = s_iova_off;
+		sg_dma_len(s) = s_length;
+		s->offset -= s_iova_off;
+		s_length = iova_align(iovad, s_length + s_iova_off);
+		s->length = s_length;
+
+		/*
+		 * Due to the alignment of our single IOVA allocation, we can
+		 * depend on these assumptions about the segment boundary mask:
+		 * - If mask size >= IOVA size, then the IOVA range cannot
+		 *   possibly fall across a boundary, so we don't care.
+		 * - If mask size < IOVA size, then the IOVA range must start
+		 *   exactly on a boundary, therefore we can lay things out
+		 *   based purely on segment lengths without needing to know
+		 *   the actual addresses beforehand.
+		 * - The mask must be a power of 2, so pad_len == 0 if
+		 *   iova_len == 0, thus we cannot dereference prev the first
+		 *   time through here (i.e. before it has a meaningful value).
+		 */
+		if (pad_len && pad_len < s_length - 1) {
+			prev->length += pad_len;
+			iova_len += pad_len;
+		}
+
+		iova_len += s_length;
+		prev = s;
+	}
+
+	iova = iommu_dma_alloc_iova(domain, iova_len, dma_get_mask(dev), dev);
+	if (!iova)
+		goto out_restore_sg;
+
+	/*
+	 * We'll leave any physical concatenation to the IOMMU driver's
+	 * implementation - it knows better than we do.
+	 */
+	if (iommu_map_sg_atomic(domain, iova, sg, nents, prot) < iova_len)
+		goto out_free_iova;
+
+	return __finalise_sg(dev, sg, nents, iova);
+
+out_free_iova:
+	iommu_dma_free_iova(cookie, iova, iova_len);
+out_restore_sg:
+	__invalidate_sg(sg, nents);
+	return 0;
+}
+
+static void iommu_dma_unmap_sg(struct device *dev, struct scatterlist *sg,
+		int nents, enum dma_data_direction dir, unsigned long attrs)
+{
+	dma_addr_t start, end;
+	struct scatterlist *tmp;
+	int i;
+
+	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		iommu_dma_sync_sg_for_cpu(dev, sg, nents, dir);
+
+	/*
+	 * The scatterlist segments are mapped into a single
+	 * contiguous IOVA allocation, so this is incredibly easy.
+	 */
+	start = sg_dma_address(sg);
+	for_each_sg(sg_next(sg), tmp, nents - 1, i) {
+		if (sg_dma_len(tmp) == 0)
+			break;
+		sg = tmp;
+	}
+	end = sg_dma_address(sg) + sg_dma_len(sg);
+	__iommu_dma_unmap(dev, start, end - start);
+}
+
+static dma_addr_t iommu_dma_map_resource(struct device *dev, phys_addr_t phys,
+		size_t size, enum dma_data_direction dir, unsigned long attrs)
+{
+	return __iommu_dma_map(dev, phys, size,
+			dma_info_to_prot(dir, false, attrs) | IOMMU_MMIO,
+			dma_get_mask(dev));
+}
+
+static void iommu_dma_unmap_resource(struct device *dev, dma_addr_t handle,
+		size_t size, enum dma_data_direction dir, unsigned long attrs)
+{
+	__iommu_dma_unmap(dev, handle, size);
+}
+
+static void __iommu_dma_free(struct device *dev, size_t size, void *cpu_addr)
+{
+	size_t alloc_size = PAGE_ALIGN(size);
+	int count = alloc_size >> PAGE_SHIFT;
+	struct page *page = NULL, **pages = NULL;
+
+	/* Non-coherent atomic allocation? Easy */
+	if (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
+	    dma_free_from_pool(dev, cpu_addr, alloc_size))
+		return;
+
+	if (IS_ENABLED(CONFIG_DMA_REMAP) && is_vmalloc_addr(cpu_addr)) {
+		/*
+		 * If it the address is remapped, then it's either non-coherent
+		 * or highmem CMA, or an iommu_dma_alloc_remap() construction.
+		 */
+		pages = dma_common_find_pages(cpu_addr);
+		if (!pages)
+			page = vmalloc_to_page(cpu_addr);
+		dma_common_free_remap(cpu_addr, alloc_size);
+	} else {
+		/* Lowmem means a coherent atomic or CMA allocation */
+		page = virt_to_page(cpu_addr);
+	}
+
+	if (pages)
+		__iommu_dma_free_pages(pages, count);
+	if (page)
+		dma_free_contiguous(dev, page, alloc_size);
+}
+
+static void iommu_dma_free(struct device *dev, size_t size, void *cpu_addr,
+		dma_addr_t handle, unsigned long attrs)
+{
+	__iommu_dma_unmap(dev, handle, size);
+	__iommu_dma_free(dev, size, cpu_addr);
+}
+
+static void *iommu_dma_alloc_pages(struct device *dev, size_t size,
+		struct page **pagep, gfp_t gfp, unsigned long attrs)
+{
+	bool coherent = dev_is_dma_coherent(dev);
+	size_t alloc_size = PAGE_ALIGN(size);
+	int node = dev_to_node(dev);
+	struct page *page = NULL;
+	void *cpu_addr;
+
+	page = dma_alloc_contiguous(dev, alloc_size, gfp);
+	if (!page)
+		page = alloc_pages_node(node, gfp, get_order(alloc_size));
+	if (!page)
+		return NULL;
+
+	if (IS_ENABLED(CONFIG_DMA_REMAP) && (!coherent || PageHighMem(page))) {
+		pgprot_t prot = dma_pgprot(dev, PAGE_KERNEL, attrs);
+
+		cpu_addr = dma_common_contiguous_remap(page, alloc_size,
+				prot, __builtin_return_address(0));
+		if (!cpu_addr)
+			goto out_free_pages;
+
+		if (!coherent)
+			arch_dma_prep_coherent(page, size);
+	} else {
+		cpu_addr = page_address(page);
+	}
+
+	*pagep = page;
+	memset(cpu_addr, 0, alloc_size);
+	return cpu_addr;
+out_free_pages:
+	dma_free_contiguous(dev, page, alloc_size);
+	return NULL;
+}
+
+static void *iommu_dma_alloc(struct device *dev, size_t size,
+		dma_addr_t *handle, gfp_t gfp, unsigned long attrs)
+{
+	bool coherent = dev_is_dma_coherent(dev);
+	int ioprot = dma_info_to_prot(DMA_BIDIRECTIONAL, coherent, attrs);
+	struct page *page = NULL;
+	void *cpu_addr;
+
+	gfp |= __GFP_ZERO;
+
+	if (IS_ENABLED(CONFIG_DMA_REMAP) && gfpflags_allow_blocking(gfp) &&
+	    !(attrs & DMA_ATTR_FORCE_CONTIGUOUS)) {
+		return iommu_dma_alloc_remap(dev, size, handle, gfp,
+				dma_pgprot(dev, PAGE_KERNEL, attrs), attrs);
+	}
+
+	if (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
+	    !gfpflags_allow_blocking(gfp) && !coherent)
+		page = dma_alloc_from_pool(dev, PAGE_ALIGN(size), &cpu_addr,
+					       gfp, NULL);
+	else
+		cpu_addr = iommu_dma_alloc_pages(dev, size, &page, gfp, attrs);
+	if (!cpu_addr)
+		return NULL;
+
+	*handle = __iommu_dma_map(dev, page_to_phys(page), size, ioprot,
+			dev->coherent_dma_mask);
+	if (*handle == DMA_MAPPING_ERROR) {
+		__iommu_dma_free(dev, size, cpu_addr);
+		return NULL;
+	}
+
+	return cpu_addr;
+}
+
+#ifdef CONFIG_DMA_REMAP
+static void *iommu_dma_alloc_noncoherent(struct device *dev, size_t size,
+		dma_addr_t *handle, enum dma_data_direction dir, gfp_t gfp)
+{
+	if (!gfpflags_allow_blocking(gfp)) {
+		struct page *page;
+
+		page = dma_common_alloc_pages(dev, size, handle, dir, gfp);
+		if (!page)
+			return NULL;
+		return page_address(page);
+	}
+
+	return iommu_dma_alloc_remap(dev, size, handle, gfp | __GFP_ZERO,
+				     PAGE_KERNEL, 0);
+}
+
+static void iommu_dma_free_noncoherent(struct device *dev, size_t size,
+		void *cpu_addr, dma_addr_t handle, enum dma_data_direction dir)
+{
+	__iommu_dma_unmap(dev, handle, size);
+	__iommu_dma_free(dev, size, cpu_addr);
+}
+#else
+#define iommu_dma_alloc_noncoherent		NULL
+#define iommu_dma_free_noncoherent		NULL
+#endif /* CONFIG_DMA_REMAP */
+
+static int iommu_dma_mmap(struct device *dev, struct vm_area_struct *vma,
+		void *cpu_addr, dma_addr_t dma_addr, size_t size,
+		unsigned long attrs)
+{
+	unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
+	unsigned long pfn, off = vma->vm_pgoff;
+	int ret;
+
+	vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);
+
+	if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
+		return ret;
+
+	if (off >= nr_pages || vma_pages(vma) > nr_pages - off)
+		return -ENXIO;
+
+	if (IS_ENABLED(CONFIG_DMA_REMAP) && is_vmalloc_addr(cpu_addr)) {
+		struct page **pages = dma_common_find_pages(cpu_addr);
+
+		if (pages)
+			return __iommu_dma_mmap(pages, size, vma);
+		pfn = vmalloc_to_pfn(cpu_addr);
+	} else {
+		pfn = page_to_pfn(virt_to_page(cpu_addr));
+	}
+
+	return remap_pfn_range(vma, vma->vm_start, pfn + off,
+			       vma->vm_end - vma->vm_start,
+			       vma->vm_page_prot);
+}
+
+static int iommu_dma_get_sgtable(struct device *dev, struct sg_table *sgt,
+		void *cpu_addr, dma_addr_t dma_addr, size_t size,
+		unsigned long attrs)
+{
+	struct page *page;
+	int ret;
+
+	if (IS_ENABLED(CONFIG_DMA_REMAP) && is_vmalloc_addr(cpu_addr)) {
+		struct page **pages = dma_common_find_pages(cpu_addr);
+
+		if (pages) {
+			return sg_alloc_table_from_pages(sgt, pages,
+					PAGE_ALIGN(size) >> PAGE_SHIFT,
+					0, size, GFP_KERNEL);
+		}
+
+		page = vmalloc_to_page(cpu_addr);
+	} else {
+		page = virt_to_page(cpu_addr);
+	}
+
+	ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
+	if (!ret)
+		sg_set_page(sgt->sgl, page, PAGE_ALIGN(size), 0);
+	return ret;
+}
+
+static unsigned long iommu_dma_get_merge_boundary(struct device *dev)
+{
+	struct iommu_domain *domain = iommu_get_dma_domain(dev);
+
+	return (1UL << __ffs(domain->pgsize_bitmap)) - 1;
+}
+
+static const struct dma_map_ops iommu_dma_ops = {
+	.alloc			= iommu_dma_alloc,
+	.free			= iommu_dma_free,
+	.alloc_pages		= dma_common_alloc_pages,
+	.free_pages		= dma_common_free_pages,
+	.alloc_noncoherent	= iommu_dma_alloc_noncoherent,
+	.free_noncoherent	= iommu_dma_free_noncoherent,
+	.mmap			= iommu_dma_mmap,
+	.get_sgtable		= iommu_dma_get_sgtable,
+	.map_page		= iommu_dma_map_page,
+	.unmap_page		= iommu_dma_unmap_page,
+	.map_sg			= iommu_dma_map_sg,
+	.unmap_sg		= iommu_dma_unmap_sg,
+	.sync_single_for_cpu	= iommu_dma_sync_single_for_cpu,
+	.sync_single_for_device	= iommu_dma_sync_single_for_device,
+	.sync_sg_for_cpu	= iommu_dma_sync_sg_for_cpu,
+	.sync_sg_for_device	= iommu_dma_sync_sg_for_device,
+	.map_resource		= iommu_dma_map_resource,
+	.unmap_resource		= iommu_dma_unmap_resource,
+	.get_merge_boundary	= iommu_dma_get_merge_boundary,
+};
+
+/*
+ * The IOMMU core code allocates the default DMA domain, which the underlying
+ * IOMMU driver needs to support via the dma-iommu layer.
+ */
+void iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 size)
+{
+	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
+
+	if (!domain)
+		goto out_err;
+
+	/*
+	 * The IOMMU core code allocates the default DMA domain, which the
+	 * underlying IOMMU driver needs to support via the dma-iommu layer.
+	 */
+	if (domain->type == IOMMU_DOMAIN_DMA) {
+		if (iommu_dma_init_domain(domain, dma_base, size, dev))
+			goto out_err;
+		dev->dma_ops = &iommu_dma_ops;
+	}
+
+	return;
+out_err:
+	 pr_warn("Failed to set up IOMMU for device %s; retaining platform DMA ops\n",
+		 dev_name(dev));
+}
+
+static struct iommu_dma_msi_page *iommu_dma_get_msi_page(struct device *dev,
+		phys_addr_t msi_addr, struct iommu_domain *domain)
+{
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	struct iommu_dma_msi_page *msi_page;
+	dma_addr_t iova;
+	int prot = IOMMU_WRITE | IOMMU_NOEXEC | IOMMU_MMIO;
+	size_t size = cookie_msi_granule(cookie);
+
+	msi_addr &= ~(phys_addr_t)(size - 1);
+	list_for_each_entry(msi_page, &cookie->msi_page_list, list)
+		if (msi_page->phys == msi_addr)
+			return msi_page;
+
+	msi_page = kzalloc(sizeof(*msi_page), GFP_KERNEL);
+	if (!msi_page)
+		return NULL;
+
+	iova = iommu_dma_alloc_iova(domain, size, dma_get_mask(dev), dev);
+	if (!iova)
+		goto out_free_page;
+
+	if (iommu_map(domain, iova, msi_addr, size, prot))
+		goto out_free_iova;
+
+	INIT_LIST_HEAD(&msi_page->list);
+	msi_page->phys = msi_addr;
+	msi_page->iova = iova;
+	list_add(&msi_page->list, &cookie->msi_page_list);
+	return msi_page;
+
+out_free_iova:
+	iommu_dma_free_iova(cookie, iova, size);
+out_free_page:
+	kfree(msi_page);
+	return NULL;
+}
+
+int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr)
+{
+	struct device *dev = msi_desc_to_dev(desc);
+	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
+	struct iommu_dma_msi_page *msi_page;
+	static DEFINE_MUTEX(msi_prepare_lock); /* see below */
+
+	if (!domain || !domain->iova_cookie) {
+		desc->iommu_cookie = NULL;
+		return 0;
+	}
+
+	/*
+	 * In fact the whole prepare operation should already be serialised by
+	 * irq_domain_mutex further up the callchain, but that's pretty subtle
+	 * on its own, so consider this locking as failsafe documentation...
+	 */
+	mutex_lock(&msi_prepare_lock);
+	msi_page = iommu_dma_get_msi_page(dev, msi_addr, domain);
+	mutex_unlock(&msi_prepare_lock);
+
+	msi_desc_set_iommu_cookie(desc, msi_page);
+
+	if (!msi_page)
+		return -ENOMEM;
+	return 0;
+}
+
+void iommu_dma_compose_msi_msg(struct msi_desc *desc,
+			       struct msi_msg *msg)
+{
+	struct device *dev = msi_desc_to_dev(desc);
+	const struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
+	const struct iommu_dma_msi_page *msi_page;
+
+	msi_page = msi_desc_get_iommu_cookie(desc);
+
+	if (!domain || !domain->iova_cookie || WARN_ON(!msi_page))
+		return;
+
+	msg->address_hi = upper_32_bits(msi_page->iova);
+	msg->address_lo &= cookie_msi_granule(domain->iova_cookie) - 1;
+	msg->address_lo += lower_32_bits(msi_page->iova);
+}
+
+static int iommu_dma_init(void)
+{
+	return iova_cache_get();
+}
+arch_initcall(iommu_dma_init);