Adding upstream version 6.1.76.upstream/6.1.76

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

1 files changed, 1105 insertions, 0 deletions

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
new file mode 100644
index 000000000..ad6333c3f
--- /dev/null
+++ b/kernel/dma/swiotlb.c
@@ -0,0 +1,1105 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Dynamic DMA mapping support.
+ *
+ * This implementation is a fallback for platforms that do not support
+ * I/O TLBs (aka DMA address translation hardware).
+ * Copyright (C) 2000 Asit Mallick <Asit.K.Mallick@intel.com>
+ * Copyright (C) 2000 Goutham Rao <goutham.rao@intel.com>
+ * Copyright (C) 2000, 2003 Hewlett-Packard Co
+ *	David Mosberger-Tang <davidm@hpl.hp.com>
+ *
+ * 03/05/07 davidm	Switch from PCI-DMA to generic device DMA API.
+ * 00/12/13 davidm	Rename to swiotlb.c and add mark_clean() to avoid
+ *			unnecessary i-cache flushing.
+ * 04/07/.. ak		Better overflow handling. Assorted fixes.
+ * 05/09/10 linville	Add support for syncing ranges, support syncing for
+ *			DMA_BIDIRECTIONAL mappings, miscellaneous cleanup.
+ * 08/12/11 beckyb	Add highmem support
+ */
+
+#define pr_fmt(fmt) "software IO TLB: " fmt
+
+#include <linux/cache.h>
+#include <linux/cc_platform.h>
+#include <linux/ctype.h>
+#include <linux/debugfs.h>
+#include <linux/dma-direct.h>
+#include <linux/dma-map-ops.h>
+#include <linux/export.h>
+#include <linux/gfp.h>
+#include <linux/highmem.h>
+#include <linux/io.h>
+#include <linux/iommu-helper.h>
+#include <linux/init.h>
+#include <linux/memblock.h>
+#include <linux/mm.h>
+#include <linux/pfn.h>
+#include <linux/scatterlist.h>
+#include <linux/set_memory.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+#include <linux/swiotlb.h>
+#include <linux/types.h>
+#ifdef CONFIG_DMA_RESTRICTED_POOL
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/of_reserved_mem.h>
+#include <linux/slab.h>
+#endif
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/swiotlb.h>
+
+#define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT))
+
+/*
+ * Minimum IO TLB size to bother booting with.  Systems with mainly
+ * 64bit capable cards will only lightly use the swiotlb.  If we can't
+ * allocate a contiguous 1MB, we're probably in trouble anyway.
+ */
+#define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT)
+
+#define INVALID_PHYS_ADDR (~(phys_addr_t)0)
+
+struct io_tlb_slot {
+	phys_addr_t orig_addr;
+	size_t alloc_size;
+	unsigned int list;
+};
+
+static bool swiotlb_force_bounce;
+static bool swiotlb_force_disable;
+
+struct io_tlb_mem io_tlb_default_mem;
+
+phys_addr_t swiotlb_unencrypted_base;
+
+static unsigned long default_nslabs = IO_TLB_DEFAULT_SIZE >> IO_TLB_SHIFT;
+static unsigned long default_nareas;
+
+/**
+ * struct io_tlb_area - IO TLB memory area descriptor
+ *
+ * This is a single area with a single lock.
+ *
+ * @used:	The number of used IO TLB block.
+ * @index:	The slot index to start searching in this area for next round.
+ * @lock:	The lock to protect the above data structures in the map and
+ *		unmap calls.
+ */
+struct io_tlb_area {
+	unsigned long used;
+	unsigned int index;
+	spinlock_t lock;
+};
+
+/*
+ * Round up number of slabs to the next power of 2. The last area is going
+ * be smaller than the rest if default_nslabs is not power of two.
+ * The number of slot in an area should be a multiple of IO_TLB_SEGSIZE,
+ * otherwise a segment may span two or more areas. It conflicts with free
+ * contiguous slots tracking: free slots are treated contiguous no matter
+ * whether they cross an area boundary.
+ *
+ * Return true if default_nslabs is rounded up.
+ */
+static bool round_up_default_nslabs(void)
+{
+	if (!default_nareas)
+		return false;
+
+	if (default_nslabs < IO_TLB_SEGSIZE * default_nareas)
+		default_nslabs = IO_TLB_SEGSIZE * default_nareas;
+	else if (is_power_of_2(default_nslabs))
+		return false;
+	default_nslabs = roundup_pow_of_two(default_nslabs);
+	return true;
+}
+
+/**
+ * swiotlb_adjust_nareas() - adjust the number of areas and slots
+ * @nareas:	Desired number of areas. Zero is treated as 1.
+ *
+ * Adjust the default number of areas in a memory pool.
+ * The default size of the memory pool may also change to meet minimum area
+ * size requirements.
+ */
+static void swiotlb_adjust_nareas(unsigned int nareas)
+{
+	if (!nareas)
+		nareas = 1;
+	else if (!is_power_of_2(nareas))
+		nareas = roundup_pow_of_two(nareas);
+
+	default_nareas = nareas;
+
+	pr_info("area num %d.\n", nareas);
+	if (round_up_default_nslabs())
+		pr_info("SWIOTLB bounce buffer size roundup to %luMB",
+			(default_nslabs << IO_TLB_SHIFT) >> 20);
+}
+
+/**
+ * limit_nareas() - get the maximum number of areas for a given memory pool size
+ * @nareas:	Desired number of areas.
+ * @nslots:	Total number of slots in the memory pool.
+ *
+ * Limit the number of areas to the maximum possible number of areas in
+ * a memory pool of the given size.
+ *
+ * Return: Maximum possible number of areas.
+ */
+static unsigned int limit_nareas(unsigned int nareas, unsigned long nslots)
+{
+	if (nslots < nareas * IO_TLB_SEGSIZE)
+		return nslots / IO_TLB_SEGSIZE;
+	return nareas;
+}
+
+static int __init
+setup_io_tlb_npages(char *str)
+{
+	if (isdigit(*str)) {
+		/* avoid tail segment of size < IO_TLB_SEGSIZE */
+		default_nslabs =
+			ALIGN(simple_strtoul(str, &str, 0), IO_TLB_SEGSIZE);
+	}
+	if (*str == ',')
+		++str;
+	if (isdigit(*str))
+		swiotlb_adjust_nareas(simple_strtoul(str, &str, 0));
+	if (*str == ',')
+		++str;
+	if (!strcmp(str, "force"))
+		swiotlb_force_bounce = true;
+	else if (!strcmp(str, "noforce"))
+		swiotlb_force_disable = true;
+
+	return 0;
+}
+early_param("swiotlb", setup_io_tlb_npages);
+
+unsigned int swiotlb_max_segment(void)
+{
+	if (!io_tlb_default_mem.nslabs)
+		return 0;
+	return rounddown(io_tlb_default_mem.nslabs << IO_TLB_SHIFT, PAGE_SIZE);
+}
+EXPORT_SYMBOL_GPL(swiotlb_max_segment);
+
+unsigned long swiotlb_size_or_default(void)
+{
+	return default_nslabs << IO_TLB_SHIFT;
+}
+
+void __init swiotlb_adjust_size(unsigned long size)
+{
+	/*
+	 * If swiotlb parameter has not been specified, give a chance to
+	 * architectures such as those supporting memory encryption to
+	 * adjust/expand SWIOTLB size for their use.
+	 */
+	if (default_nslabs != IO_TLB_DEFAULT_SIZE >> IO_TLB_SHIFT)
+		return;
+
+	size = ALIGN(size, IO_TLB_SIZE);
+	default_nslabs = ALIGN(size >> IO_TLB_SHIFT, IO_TLB_SEGSIZE);
+	if (round_up_default_nslabs())
+		size = default_nslabs << IO_TLB_SHIFT;
+	pr_info("SWIOTLB bounce buffer size adjusted to %luMB", size >> 20);
+}
+
+void swiotlb_print_info(void)
+{
+	struct io_tlb_mem *mem = &io_tlb_default_mem;
+
+	if (!mem->nslabs) {
+		pr_warn("No low mem\n");
+		return;
+	}
+
+	pr_info("mapped [mem %pa-%pa] (%luMB)\n", &mem->start, &mem->end,
+	       (mem->nslabs << IO_TLB_SHIFT) >> 20);
+}
+
+static inline unsigned long io_tlb_offset(unsigned long val)
+{
+	return val & (IO_TLB_SEGSIZE - 1);
+}
+
+static inline unsigned long nr_slots(u64 val)
+{
+	return DIV_ROUND_UP(val, IO_TLB_SIZE);
+}
+
+/*
+ * Remap swioltb memory in the unencrypted physical address space
+ * when swiotlb_unencrypted_base is set. (e.g. for Hyper-V AMD SEV-SNP
+ * Isolation VMs).
+ */
+#ifdef CONFIG_HAS_IOMEM
+static void *swiotlb_mem_remap(struct io_tlb_mem *mem, unsigned long bytes)
+{
+	void *vaddr = NULL;
+
+	if (swiotlb_unencrypted_base) {
+		phys_addr_t paddr = mem->start + swiotlb_unencrypted_base;
+
+		vaddr = memremap(paddr, bytes, MEMREMAP_WB);
+		if (!vaddr)
+			pr_err("Failed to map the unencrypted memory %pa size %lx.\n",
+			       &paddr, bytes);
+	}
+
+	return vaddr;
+}
+#else
+static void *swiotlb_mem_remap(struct io_tlb_mem *mem, unsigned long bytes)
+{
+	return NULL;
+}
+#endif
+
+/*
+ * Early SWIOTLB allocation may be too early to allow an architecture to
+ * perform the desired operations.  This function allows the architecture to
+ * call SWIOTLB when the operations are possible.  It needs to be called
+ * before the SWIOTLB memory is used.
+ */
+void __init swiotlb_update_mem_attributes(void)
+{
+	struct io_tlb_mem *mem = &io_tlb_default_mem;
+	void *vaddr;
+	unsigned long bytes;
+
+	if (!mem->nslabs || mem->late_alloc)
+		return;
+	vaddr = phys_to_virt(mem->start);
+	bytes = PAGE_ALIGN(mem->nslabs << IO_TLB_SHIFT);
+	set_memory_decrypted((unsigned long)vaddr, bytes >> PAGE_SHIFT);
+
+	mem->vaddr = swiotlb_mem_remap(mem, bytes);
+	if (!mem->vaddr)
+		mem->vaddr = vaddr;
+}
+
+static void swiotlb_init_io_tlb_mem(struct io_tlb_mem *mem, phys_addr_t start,
+		unsigned long nslabs, unsigned int flags,
+		bool late_alloc, unsigned int nareas)
+{
+	void *vaddr = phys_to_virt(start);
+	unsigned long bytes = nslabs << IO_TLB_SHIFT, i;
+
+	mem->nslabs = nslabs;
+	mem->start = start;
+	mem->end = mem->start + bytes;
+	mem->late_alloc = late_alloc;
+	mem->nareas = nareas;
+	mem->area_nslabs = nslabs / mem->nareas;
+
+	mem->force_bounce = swiotlb_force_bounce || (flags & SWIOTLB_FORCE);
+
+	for (i = 0; i < mem->nareas; i++) {
+		spin_lock_init(&mem->areas[i].lock);
+		mem->areas[i].index = 0;
+		mem->areas[i].used = 0;
+	}
+
+	for (i = 0; i < mem->nslabs; i++) {
+		mem->slots[i].list = IO_TLB_SEGSIZE - io_tlb_offset(i);
+		mem->slots[i].orig_addr = INVALID_PHYS_ADDR;
+		mem->slots[i].alloc_size = 0;
+	}
+
+	/*
+	 * If swiotlb_unencrypted_base is set, the bounce buffer memory will
+	 * be remapped and cleared in swiotlb_update_mem_attributes.
+	 */
+	if (swiotlb_unencrypted_base)
+		return;
+
+	memset(vaddr, 0, bytes);
+	mem->vaddr = vaddr;
+	return;
+}
+
+static void __init *swiotlb_memblock_alloc(unsigned long nslabs,
+		unsigned int flags,
+		int (*remap)(void *tlb, unsigned long nslabs))
+{
+	size_t bytes = PAGE_ALIGN(nslabs << IO_TLB_SHIFT);
+	void *tlb;
+
+	/*
+	 * By default allocate the bounce buffer memory from low memory, but
+	 * allow to pick a location everywhere for hypervisors with guest
+	 * memory encryption.
+	 */
+	if (flags & SWIOTLB_ANY)
+		tlb = memblock_alloc(bytes, PAGE_SIZE);
+	else
+		tlb = memblock_alloc_low(bytes, PAGE_SIZE);
+
+	if (!tlb) {
+		pr_warn("%s: Failed to allocate %zu bytes tlb structure\n",
+			__func__, bytes);
+		return NULL;
+	}
+
+	if (remap && remap(tlb, nslabs) < 0) {
+		memblock_free(tlb, PAGE_ALIGN(bytes));
+		pr_warn("%s: Failed to remap %zu bytes\n", __func__, bytes);
+		return NULL;
+	}
+
+	return tlb;
+}
+
+/*
+ * Statically reserve bounce buffer space and initialize bounce buffer data
+ * structures for the software IO TLB used to implement the DMA API.
+ */
+void __init swiotlb_init_remap(bool addressing_limit, unsigned int flags,
+		int (*remap)(void *tlb, unsigned long nslabs))
+{
+	struct io_tlb_mem *mem = &io_tlb_default_mem;
+	unsigned long nslabs;
+	unsigned int nareas;
+	size_t alloc_size;
+	void *tlb;
+
+	if (!addressing_limit && !swiotlb_force_bounce)
+		return;
+	if (swiotlb_force_disable)
+		return;
+
+	if (!default_nareas)
+		swiotlb_adjust_nareas(num_possible_cpus());
+
+	nslabs = default_nslabs;
+	nareas = limit_nareas(default_nareas, nslabs);
+	while ((tlb = swiotlb_memblock_alloc(nslabs, flags, remap)) == NULL) {
+		if (nslabs <= IO_TLB_MIN_SLABS)
+			return;
+		nslabs = ALIGN(nslabs >> 1, IO_TLB_SEGSIZE);
+		nareas = limit_nareas(nareas, nslabs);
+	}
+
+	if (default_nslabs != nslabs) {
+		pr_info("SWIOTLB bounce buffer size adjusted %lu -> %lu slabs",
+			default_nslabs, nslabs);
+		default_nslabs = nslabs;
+	}
+
+	alloc_size = PAGE_ALIGN(array_size(sizeof(*mem->slots), nslabs));
+	mem->slots = memblock_alloc(alloc_size, PAGE_SIZE);
+	if (!mem->slots) {
+		pr_warn("%s: Failed to allocate %zu bytes align=0x%lx\n",
+			__func__, alloc_size, PAGE_SIZE);
+		return;
+	}
+
+	mem->areas = memblock_alloc(array_size(sizeof(struct io_tlb_area),
+		default_nareas), SMP_CACHE_BYTES);
+	if (!mem->areas) {
+		pr_warn("%s: Failed to allocate mem->areas.\n", __func__);
+		return;
+	}
+
+	swiotlb_init_io_tlb_mem(mem, __pa(tlb), nslabs, flags, false,
+				default_nareas);
+
+	if (flags & SWIOTLB_VERBOSE)
+		swiotlb_print_info();
+}
+
+void __init swiotlb_init(bool addressing_limit, unsigned int flags)
+{
+	swiotlb_init_remap(addressing_limit, flags, NULL);
+}
+
+/*
+ * Systems with larger DMA zones (those that don't support ISA) can
+ * initialize the swiotlb later using the slab allocator if needed.
+ * This should be just like above, but with some error catching.
+ */
+int swiotlb_init_late(size_t size, gfp_t gfp_mask,
+		int (*remap)(void *tlb, unsigned long nslabs))
+{
+	struct io_tlb_mem *mem = &io_tlb_default_mem;
+	unsigned long nslabs = ALIGN(size >> IO_TLB_SHIFT, IO_TLB_SEGSIZE);
+	unsigned int nareas;
+	unsigned char *vstart = NULL;
+	unsigned int order, area_order;
+	bool retried = false;
+	int rc = 0;
+
+	if (swiotlb_force_disable)
+		return 0;
+
+	if (!default_nareas)
+		swiotlb_adjust_nareas(num_possible_cpus());
+
+retry:
+	order = get_order(nslabs << IO_TLB_SHIFT);
+	nslabs = SLABS_PER_PAGE << order;
+
+	while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
+		vstart = (void *)__get_free_pages(gfp_mask | __GFP_NOWARN,
+						  order);
+		if (vstart)
+			break;
+		order--;
+		nslabs = SLABS_PER_PAGE << order;
+		retried = true;
+	}
+
+	if (!vstart)
+		return -ENOMEM;
+
+	if (remap)
+		rc = remap(vstart, nslabs);
+	if (rc) {
+		free_pages((unsigned long)vstart, order);
+
+		nslabs = ALIGN(nslabs >> 1, IO_TLB_SEGSIZE);
+		if (nslabs < IO_TLB_MIN_SLABS)
+			return rc;
+		retried = true;
+		goto retry;
+	}
+
+	if (retried) {
+		pr_warn("only able to allocate %ld MB\n",
+			(PAGE_SIZE << order) >> 20);
+	}
+
+	nareas = limit_nareas(default_nareas, nslabs);
+	area_order = get_order(array_size(sizeof(*mem->areas), nareas));
+	mem->areas = (struct io_tlb_area *)
+		__get_free_pages(GFP_KERNEL | __GFP_ZERO, area_order);
+	if (!mem->areas)
+		goto error_area;
+
+	mem->slots = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
+		get_order(array_size(sizeof(*mem->slots), nslabs)));
+	if (!mem->slots)
+		goto error_slots;
+
+	set_memory_decrypted((unsigned long)vstart,
+			     (nslabs << IO_TLB_SHIFT) >> PAGE_SHIFT);
+	swiotlb_init_io_tlb_mem(mem, virt_to_phys(vstart), nslabs, 0, true,
+				nareas);
+
+	swiotlb_print_info();
+	return 0;
+
+error_slots:
+	free_pages((unsigned long)mem->areas, area_order);
+error_area:
+	free_pages((unsigned long)vstart, order);
+	return -ENOMEM;
+}
+
+void __init swiotlb_exit(void)
+{
+	struct io_tlb_mem *mem = &io_tlb_default_mem;
+	unsigned long tbl_vaddr;
+	size_t tbl_size, slots_size;
+	unsigned int area_order;
+
+	if (swiotlb_force_bounce)
+		return;
+
+	if (!mem->nslabs)
+		return;
+
+	pr_info("tearing down default memory pool\n");
+	tbl_vaddr = (unsigned long)phys_to_virt(mem->start);
+	tbl_size = PAGE_ALIGN(mem->end - mem->start);
+	slots_size = PAGE_ALIGN(array_size(sizeof(*mem->slots), mem->nslabs));
+
+	set_memory_encrypted(tbl_vaddr, tbl_size >> PAGE_SHIFT);
+	if (mem->late_alloc) {
+		area_order = get_order(array_size(sizeof(*mem->areas),
+			mem->nareas));
+		free_pages((unsigned long)mem->areas, area_order);
+		free_pages(tbl_vaddr, get_order(tbl_size));
+		free_pages((unsigned long)mem->slots, get_order(slots_size));
+	} else {
+		memblock_free_late(__pa(mem->areas),
+			array_size(sizeof(*mem->areas), mem->nareas));
+		memblock_free_late(mem->start, tbl_size);
+		memblock_free_late(__pa(mem->slots), slots_size);
+	}
+
+	memset(mem, 0, sizeof(*mem));
+}
+
+/*
+ * Return the offset into a iotlb slot required to keep the device happy.
+ */
+static unsigned int swiotlb_align_offset(struct device *dev, u64 addr)
+{
+	return addr & dma_get_min_align_mask(dev) & (IO_TLB_SIZE - 1);
+}
+
+/*
+ * Bounce: copy the swiotlb buffer from or back to the original dma location
+ */
+static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t size,
+			   enum dma_data_direction dir)
+{
+	struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
+	int index = (tlb_addr - mem->start) >> IO_TLB_SHIFT;
+	phys_addr_t orig_addr = mem->slots[index].orig_addr;
+	size_t alloc_size = mem->slots[index].alloc_size;
+	unsigned long pfn = PFN_DOWN(orig_addr);
+	unsigned char *vaddr = mem->vaddr + tlb_addr - mem->start;
+	unsigned int tlb_offset, orig_addr_offset;
+
+	if (orig_addr == INVALID_PHYS_ADDR)
+		return;
+
+	tlb_offset = tlb_addr & (IO_TLB_SIZE - 1);
+	orig_addr_offset = swiotlb_align_offset(dev, orig_addr);
+	if (tlb_offset < orig_addr_offset) {
+		dev_WARN_ONCE(dev, 1,
+			"Access before mapping start detected. orig offset %u, requested offset %u.\n",
+			orig_addr_offset, tlb_offset);
+		return;
+	}
+
+	tlb_offset -= orig_addr_offset;
+	if (tlb_offset > alloc_size) {
+		dev_WARN_ONCE(dev, 1,
+			"Buffer overflow detected. Allocation size: %zu. Mapping size: %zu+%u.\n",
+			alloc_size, size, tlb_offset);
+		return;
+	}
+
+	orig_addr += tlb_offset;
+	alloc_size -= tlb_offset;
+
+	if (size > alloc_size) {
+		dev_WARN_ONCE(dev, 1,
+			"Buffer overflow detected. Allocation size: %zu. Mapping size: %zu.\n",
+			alloc_size, size);
+		size = alloc_size;
+	}
+
+	if (PageHighMem(pfn_to_page(pfn))) {
+		unsigned int offset = orig_addr & ~PAGE_MASK;
+		struct page *page;
+		unsigned int sz = 0;
+		unsigned long flags;
+
+		while (size) {
+			sz = min_t(size_t, PAGE_SIZE - offset, size);
+
+			local_irq_save(flags);
+			page = pfn_to_page(pfn);
+			if (dir == DMA_TO_DEVICE)
+				memcpy_from_page(vaddr, page, offset, sz);
+			else
+				memcpy_to_page(page, offset, vaddr, sz);
+			local_irq_restore(flags);
+
+			size -= sz;
+			pfn++;
+			vaddr += sz;
+			offset = 0;
+		}
+	} else if (dir == DMA_TO_DEVICE) {
+		memcpy(vaddr, phys_to_virt(orig_addr), size);
+	} else {
+		memcpy(phys_to_virt(orig_addr), vaddr, size);
+	}
+}
+
+static inline phys_addr_t slot_addr(phys_addr_t start, phys_addr_t idx)
+{
+	return start + (idx << IO_TLB_SHIFT);
+}
+
+/*
+ * Carefully handle integer overflow which can occur when boundary_mask == ~0UL.
+ */
+static inline unsigned long get_max_slots(unsigned long boundary_mask)
+{
+	if (boundary_mask == ~0UL)
+		return 1UL << (BITS_PER_LONG - IO_TLB_SHIFT);
+	return nr_slots(boundary_mask + 1);
+}
+
+static unsigned int wrap_area_index(struct io_tlb_mem *mem, unsigned int index)
+{
+	if (index >= mem->area_nslabs)
+		return 0;
+	return index;
+}
+
+/*
+ * Find a suitable number of IO TLB entries size that will fit this request and
+ * allocate a buffer from that IO TLB pool.
+ */
+static int swiotlb_do_find_slots(struct device *dev, int area_index,
+		phys_addr_t orig_addr, size_t alloc_size,
+		unsigned int alloc_align_mask)
+{
+	struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
+	struct io_tlb_area *area = mem->areas + area_index;
+	unsigned long boundary_mask = dma_get_seg_boundary(dev);
+	dma_addr_t tbl_dma_addr =
+		phys_to_dma_unencrypted(dev, mem->start) & boundary_mask;
+	unsigned long max_slots = get_max_slots(boundary_mask);
+	unsigned int iotlb_align_mask =
+		dma_get_min_align_mask(dev) & ~(IO_TLB_SIZE - 1);
+	unsigned int nslots = nr_slots(alloc_size), stride;
+	unsigned int index, wrap, count = 0, i;
+	unsigned int offset = swiotlb_align_offset(dev, orig_addr);
+	unsigned long flags;
+	unsigned int slot_base;
+	unsigned int slot_index;
+
+	BUG_ON(!nslots);
+	BUG_ON(area_index >= mem->nareas);
+
+	/*
+	 * For mappings with an alignment requirement don't bother looping to
+	 * unaligned slots once we found an aligned one.  For allocations of
+	 * PAGE_SIZE or larger only look for page aligned allocations.
+	 */
+	stride = (iotlb_align_mask >> IO_TLB_SHIFT) + 1;
+	if (alloc_size >= PAGE_SIZE)
+		stride = max(stride, stride << (PAGE_SHIFT - IO_TLB_SHIFT));
+	stride = max(stride, (alloc_align_mask >> IO_TLB_SHIFT) + 1);
+
+	spin_lock_irqsave(&area->lock, flags);
+	if (unlikely(nslots > mem->area_nslabs - area->used))
+		goto not_found;
+
+	slot_base = area_index * mem->area_nslabs;
+	index = wrap = wrap_area_index(mem, ALIGN(area->index, stride));
+
+	do {
+		slot_index = slot_base + index;
+
+		if (orig_addr &&
+		    (slot_addr(tbl_dma_addr, slot_index) &
+		     iotlb_align_mask) != (orig_addr & iotlb_align_mask)) {
+			index = wrap_area_index(mem, index + 1);
+			continue;
+		}
+
+		/*
+		 * If we find a slot that indicates we have 'nslots' number of
+		 * contiguous buffers, we allocate the buffers from that slot
+		 * and mark the entries as '0' indicating unavailable.
+		 */
+		if (!iommu_is_span_boundary(slot_index, nslots,
+					    nr_slots(tbl_dma_addr),
+					    max_slots)) {
+			if (mem->slots[slot_index].list >= nslots)
+				goto found;
+		}
+		index = wrap_area_index(mem, index + stride);
+	} while (index != wrap);
+
+not_found:
+	spin_unlock_irqrestore(&area->lock, flags);
+	return -1;
+
+found:
+	for (i = slot_index; i < slot_index + nslots; i++) {
+		mem->slots[i].list = 0;
+		mem->slots[i].alloc_size = alloc_size - (offset +
+				((i - slot_index) << IO_TLB_SHIFT));
+	}
+	for (i = slot_index - 1;
+	     io_tlb_offset(i) != IO_TLB_SEGSIZE - 1 &&
+	     mem->slots[i].list; i--)
+		mem->slots[i].list = ++count;
+
+	/*
+	 * Update the indices to avoid searching in the next round.
+	 */
+	if (index + nslots < mem->area_nslabs)
+		area->index = index + nslots;
+	else
+		area->index = 0;
+	area->used += nslots;
+	spin_unlock_irqrestore(&area->lock, flags);
+	return slot_index;
+}
+
+static int swiotlb_find_slots(struct device *dev, phys_addr_t orig_addr,
+		size_t alloc_size, unsigned int alloc_align_mask)
+{
+	struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
+	int start = raw_smp_processor_id() & (mem->nareas - 1);
+	int i = start, index;
+
+	do {
+		index = swiotlb_do_find_slots(dev, i, orig_addr, alloc_size,
+					      alloc_align_mask);
+		if (index >= 0)
+			return index;
+		if (++i >= mem->nareas)
+			i = 0;
+	} while (i != start);
+
+	return -1;
+}
+
+static unsigned long mem_used(struct io_tlb_mem *mem)
+{
+	int i;
+	unsigned long used = 0;
+
+	for (i = 0; i < mem->nareas; i++)
+		used += mem->areas[i].used;
+	return used;
+}
+
+phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr,
+		size_t mapping_size, size_t alloc_size,
+		unsigned int alloc_align_mask, enum dma_data_direction dir,
+		unsigned long attrs)
+{
+	struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
+	unsigned int offset = swiotlb_align_offset(dev, orig_addr);
+	unsigned int i;
+	int index;
+	phys_addr_t tlb_addr;
+
+	if (!mem || !mem->nslabs) {
+		dev_warn_ratelimited(dev,
+			"Can not allocate SWIOTLB buffer earlier and can't now provide you with the DMA bounce buffer");
+		return (phys_addr_t)DMA_MAPPING_ERROR;
+	}
+
+	if (cc_platform_has(CC_ATTR_MEM_ENCRYPT))
+		pr_warn_once("Memory encryption is active and system is using DMA bounce buffers\n");
+
+	if (mapping_size > alloc_size) {
+		dev_warn_once(dev, "Invalid sizes (mapping: %zd bytes, alloc: %zd bytes)",
+			      mapping_size, alloc_size);
+		return (phys_addr_t)DMA_MAPPING_ERROR;
+	}
+
+	index = swiotlb_find_slots(dev, orig_addr,
+				   alloc_size + offset, alloc_align_mask);
+	if (index == -1) {
+		if (!(attrs & DMA_ATTR_NO_WARN))
+			dev_warn_ratelimited(dev,
+	"swiotlb buffer is full (sz: %zd bytes), total %lu (slots), used %lu (slots)\n",
+				 alloc_size, mem->nslabs, mem_used(mem));
+		return (phys_addr_t)DMA_MAPPING_ERROR;
+	}
+
+	/*
+	 * Save away the mapping from the original address to the DMA address.
+	 * This is needed when we sync the memory.  Then we sync the buffer if
+	 * needed.
+	 */
+	for (i = 0; i < nr_slots(alloc_size + offset); i++)
+		mem->slots[index + i].orig_addr = slot_addr(orig_addr, i);
+	tlb_addr = slot_addr(mem->start, index) + offset;
+	/*
+	 * When dir == DMA_FROM_DEVICE we could omit the copy from the orig
+	 * to the tlb buffer, if we knew for sure the device will
+	 * overwrite the entire current content. But we don't. Thus
+	 * unconditional bounce may prevent leaking swiotlb content (i.e.
+	 * kernel memory) to user-space.
+	 */
+	swiotlb_bounce(dev, tlb_addr, mapping_size, DMA_TO_DEVICE);
+	return tlb_addr;
+}
+
+static void swiotlb_release_slots(struct device *dev, phys_addr_t tlb_addr)
+{
+	struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
+	unsigned long flags;
+	unsigned int offset = swiotlb_align_offset(dev, tlb_addr);
+	int index = (tlb_addr - offset - mem->start) >> IO_TLB_SHIFT;
+	int nslots = nr_slots(mem->slots[index].alloc_size + offset);
+	int aindex = index / mem->area_nslabs;
+	struct io_tlb_area *area = &mem->areas[aindex];
+	int count, i;
+
+	/*
+	 * Return the buffer to the free list by setting the corresponding
+	 * entries to indicate the number of contiguous entries available.
+	 * While returning the entries to the free list, we merge the entries
+	 * with slots below and above the pool being returned.
+	 */
+	BUG_ON(aindex >= mem->nareas);
+
+	spin_lock_irqsave(&area->lock, flags);
+	if (index + nslots < ALIGN(index + 1, IO_TLB_SEGSIZE))
+		count = mem->slots[index + nslots].list;
+	else
+		count = 0;
+
+	/*
+	 * Step 1: return the slots to the free list, merging the slots with
+	 * superceeding slots
+	 */
+	for (i = index + nslots - 1; i >= index; i--) {
+		mem->slots[i].list = ++count;
+		mem->slots[i].orig_addr = INVALID_PHYS_ADDR;
+		mem->slots[i].alloc_size = 0;
+	}
+
+	/*
+	 * Step 2: merge the returned slots with the preceding slots, if
+	 * available (non zero)
+	 */
+	for (i = index - 1;
+	     io_tlb_offset(i) != IO_TLB_SEGSIZE - 1 && mem->slots[i].list;
+	     i--)
+		mem->slots[i].list = ++count;
+	area->used -= nslots;
+	spin_unlock_irqrestore(&area->lock, flags);
+}
+
+/*
+ * tlb_addr is the physical address of the bounce buffer to unmap.
+ */
+void swiotlb_tbl_unmap_single(struct device *dev, phys_addr_t tlb_addr,
+			      size_t mapping_size, enum dma_data_direction dir,
+			      unsigned long attrs)
+{
+	/*
+	 * First, sync the memory before unmapping the entry
+	 */
+	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
+	    (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL))
+		swiotlb_bounce(dev, tlb_addr, mapping_size, DMA_FROM_DEVICE);
+
+	swiotlb_release_slots(dev, tlb_addr);
+}
+
+void swiotlb_sync_single_for_device(struct device *dev, phys_addr_t tlb_addr,
+		size_t size, enum dma_data_direction dir)
+{
+	if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL)
+		swiotlb_bounce(dev, tlb_addr, size, DMA_TO_DEVICE);
+	else
+		BUG_ON(dir != DMA_FROM_DEVICE);
+}
+
+void swiotlb_sync_single_for_cpu(struct device *dev, phys_addr_t tlb_addr,
+		size_t size, enum dma_data_direction dir)
+{
+	if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL)
+		swiotlb_bounce(dev, tlb_addr, size, DMA_FROM_DEVICE);
+	else
+		BUG_ON(dir != DMA_TO_DEVICE);
+}
+
+/*
+ * Create a swiotlb mapping for the buffer at @paddr, and in case of DMAing
+ * to the device copy the data into it as well.
+ */
+dma_addr_t swiotlb_map(struct device *dev, phys_addr_t paddr, size_t size,
+		enum dma_data_direction dir, unsigned long attrs)
+{
+	phys_addr_t swiotlb_addr;
+	dma_addr_t dma_addr;
+
+	trace_swiotlb_bounced(dev, phys_to_dma(dev, paddr), size);
+
+	swiotlb_addr = swiotlb_tbl_map_single(dev, paddr, size, size, 0, dir,
+			attrs);
+	if (swiotlb_addr == (phys_addr_t)DMA_MAPPING_ERROR)
+		return DMA_MAPPING_ERROR;
+
+	/* Ensure that the address returned is DMA'ble */
+	dma_addr = phys_to_dma_unencrypted(dev, swiotlb_addr);
+	if (unlikely(!dma_capable(dev, dma_addr, size, true))) {
+		swiotlb_tbl_unmap_single(dev, swiotlb_addr, size, dir,
+			attrs | DMA_ATTR_SKIP_CPU_SYNC);
+		dev_WARN_ONCE(dev, 1,
+			"swiotlb addr %pad+%zu overflow (mask %llx, bus limit %llx).\n",
+			&dma_addr, size, *dev->dma_mask, dev->bus_dma_limit);
+		return DMA_MAPPING_ERROR;
+	}
+
+	if (!dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		arch_sync_dma_for_device(swiotlb_addr, size, dir);
+	return dma_addr;
+}
+
+size_t swiotlb_max_mapping_size(struct device *dev)
+{
+	int min_align_mask = dma_get_min_align_mask(dev);
+	int min_align = 0;
+
+	/*
+	 * swiotlb_find_slots() skips slots according to
+	 * min align mask. This affects max mapping size.
+	 * Take it into acount here.
+	 */
+	if (min_align_mask)
+		min_align = roundup(min_align_mask, IO_TLB_SIZE);
+
+	return ((size_t)IO_TLB_SIZE) * IO_TLB_SEGSIZE - min_align;
+}
+
+bool is_swiotlb_active(struct device *dev)
+{
+	struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
+
+	return mem && mem->nslabs;
+}
+EXPORT_SYMBOL_GPL(is_swiotlb_active);
+
+static int io_tlb_used_get(void *data, u64 *val)
+{
+	struct io_tlb_mem *mem = data;
+
+	*val = mem_used(mem);
+	return 0;
+}
+DEFINE_DEBUGFS_ATTRIBUTE(fops_io_tlb_used, io_tlb_used_get, NULL, "%llu\n");
+
+static void swiotlb_create_debugfs_files(struct io_tlb_mem *mem,
+					 const char *dirname)
+{
+	mem->debugfs = debugfs_create_dir(dirname, io_tlb_default_mem.debugfs);
+	if (!mem->nslabs)
+		return;
+
+	debugfs_create_ulong("io_tlb_nslabs", 0400, mem->debugfs, &mem->nslabs);
+	debugfs_create_file("io_tlb_used", 0400, mem->debugfs, mem,
+			&fops_io_tlb_used);
+}
+
+static int __init __maybe_unused swiotlb_create_default_debugfs(void)
+{
+	swiotlb_create_debugfs_files(&io_tlb_default_mem, "swiotlb");
+	return 0;
+}
+
+#ifdef CONFIG_DEBUG_FS
+late_initcall(swiotlb_create_default_debugfs);
+#endif
+
+#ifdef CONFIG_DMA_RESTRICTED_POOL
+
+struct page *swiotlb_alloc(struct device *dev, size_t size)
+{
+	struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
+	phys_addr_t tlb_addr;
+	int index;
+
+	if (!mem)
+		return NULL;
+
+	index = swiotlb_find_slots(dev, 0, size, 0);
+	if (index == -1)
+		return NULL;
+
+	tlb_addr = slot_addr(mem->start, index);
+
+	return pfn_to_page(PFN_DOWN(tlb_addr));
+}
+
+bool swiotlb_free(struct device *dev, struct page *page, size_t size)
+{
+	phys_addr_t tlb_addr = page_to_phys(page);
+
+	if (!is_swiotlb_buffer(dev, tlb_addr))
+		return false;
+
+	swiotlb_release_slots(dev, tlb_addr);
+
+	return true;
+}
+
+static int rmem_swiotlb_device_init(struct reserved_mem *rmem,
+				    struct device *dev)
+{
+	struct io_tlb_mem *mem = rmem->priv;
+	unsigned long nslabs = rmem->size >> IO_TLB_SHIFT;
+
+	/* Set Per-device io tlb area to one */
+	unsigned int nareas = 1;
+
+	if (PageHighMem(pfn_to_page(PHYS_PFN(rmem->base)))) {
+		dev_err(dev, "Restricted DMA pool must be accessible within the linear mapping.");
+		return -EINVAL;
+	}
+
+	/*
+	 * Since multiple devices can share the same pool, the private data,
+	 * io_tlb_mem struct, will be initialized by the first device attached
+	 * to it.
+	 */
+	if (!mem) {
+		mem = kzalloc(sizeof(*mem), GFP_KERNEL);
+		if (!mem)
+			return -ENOMEM;
+
+		mem->slots = kcalloc(nslabs, sizeof(*mem->slots), GFP_KERNEL);
+		if (!mem->slots) {
+			kfree(mem);
+			return -ENOMEM;
+		}
+
+		mem->areas = kcalloc(nareas, sizeof(*mem->areas),
+				GFP_KERNEL);
+		if (!mem->areas) {
+			kfree(mem->slots);
+			kfree(mem);
+			return -ENOMEM;
+		}
+
+		set_memory_decrypted((unsigned long)phys_to_virt(rmem->base),
+				     rmem->size >> PAGE_SHIFT);
+		swiotlb_init_io_tlb_mem(mem, rmem->base, nslabs, SWIOTLB_FORCE,
+					false, nareas);
+		mem->for_alloc = true;
+
+		rmem->priv = mem;
+
+		swiotlb_create_debugfs_files(mem, rmem->name);
+	}
+
+	dev->dma_io_tlb_mem = mem;
+
+	return 0;
+}
+
+static void rmem_swiotlb_device_release(struct reserved_mem *rmem,
+					struct device *dev)
+{
+	dev->dma_io_tlb_mem = &io_tlb_default_mem;
+}
+
+static const struct reserved_mem_ops rmem_swiotlb_ops = {
+	.device_init = rmem_swiotlb_device_init,
+	.device_release = rmem_swiotlb_device_release,
+};
+
+static int __init rmem_swiotlb_setup(struct reserved_mem *rmem)
+{
+	unsigned long node = rmem->fdt_node;
+
+	if (of_get_flat_dt_prop(node, "reusable", NULL) ||
+	    of_get_flat_dt_prop(node, "linux,cma-default", NULL) ||
+	    of_get_flat_dt_prop(node, "linux,dma-default", NULL) ||
+	    of_get_flat_dt_prop(node, "no-map", NULL))
+		return -EINVAL;
+
+	rmem->ops = &rmem_swiotlb_ops;
+	pr_info("Reserved memory: created restricted DMA pool at %pa, size %ld MiB\n",
+		&rmem->base, (unsigned long)rmem->size / SZ_1M);
+	return 0;
+}
+
+RESERVEDMEM_OF_DECLARE(dma, "restricted-dma-pool", rmem_swiotlb_setup);
+#endif /* CONFIG_DMA_RESTRICTED_POOL */