Merge branch 'stable/for-linus-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb

Pull swiotlb updates from Konrad Rzeszutek Wilk:
 "A new feature called restricted DMA pools. It allows SWIOTLB to
  utilize per-device (or per-platform) allocated memory pools instead of
  using the global one.

  The first big user of this is ARM Confidential Computing where the
  memory for DMA operations can be set per platform"

* 'stable/for-linus-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb: (23 commits)
  swiotlb: use depends on for DMA_RESTRICTED_POOL
  of: restricted dma: Don't fail device probe on rmem init failure
  of: Move of_dma_set_restricted_buffer() into device.c
  powerpc/svm: Don't issue ultracalls if !mem_encrypt_active()
  s390/pv: fix the forcing of the swiotlb
  swiotlb: Free tbl memory in swiotlb_exit()
  swiotlb: Emit diagnostic in swiotlb_exit()
  swiotlb: Convert io_default_tlb_mem to static allocation
  of: Return success from of_dma_set_restricted_buffer() when !OF_ADDRESS
  swiotlb: add overflow checks to swiotlb_bounce
  swiotlb: fix implicit debugfs declarations
  of: Add plumbing for restricted DMA pool
  dt-bindings: of: Add restricted DMA pool
  swiotlb: Add restricted DMA pool initialization
  swiotlb: Add restricted DMA alloc/free support
  swiotlb: Refactor swiotlb_tbl_unmap_single
  swiotlb: Move alloc_size to swiotlb_find_slots
  swiotlb: Use is_swiotlb_force_bounce for swiotlb data bouncing
  swiotlb: Update is_swiotlb_active to add a struct device argument
  swiotlb: Update is_swiotlb_buffer to add a struct device argument
  ...

4 files changed, 319 insertions, 111 deletions

diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig
index 725cfd51762b..1b02179758cb 100644
--- a/kernel/dma/Kconfig
+++ b/kernel/dma/Kconfig
@@ -80,6 +80,19 @@ config SWIOTLB
 	bool
 	select NEED_DMA_MAP_STATE
 
+config DMA_RESTRICTED_POOL
+	bool "DMA Restricted Pool"
+	depends on OF && OF_RESERVED_MEM && SWIOTLB
+	help
+	  This enables support for restricted DMA pools which provide a level of
+	  DMA memory protection on systems with limited hardware protection
+	  capabilities, such as those lacking an IOMMU.
+
+	  For more information see
+	  <Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt>
+	  and <kernel/dma/swiotlb.c>.
+	  If unsure, say "n".
+
 #
 # Should be selected if we can mmap non-coherent mappings to userspace.
 # The only thing that is really required is a way to set an uncached bit
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 8dca4f97d12d..4c6c5e0635e3 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -75,6 +75,15 @@ static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
 		min_not_zero(dev->coherent_dma_mask, dev->bus_dma_limit);
 }
 
+static void __dma_direct_free_pages(struct device *dev, struct page *page,
+				    size_t size)
+{
+	if (IS_ENABLED(CONFIG_DMA_RESTRICTED_POOL) &&
+	    swiotlb_free(dev, page, size))
+		return;
+	dma_free_contiguous(dev, page, size);
+}
+
 static struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
 		gfp_t gfp)
 {
@@ -86,6 +95,16 @@ static struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
 
 	gfp |= dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask,
 					   &phys_limit);
+	if (IS_ENABLED(CONFIG_DMA_RESTRICTED_POOL) &&
+	    is_swiotlb_for_alloc(dev)) {
+		page = swiotlb_alloc(dev, size);
+		if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
+			__dma_direct_free_pages(dev, page, size);
+			return NULL;
+		}
+		return page;
+	}
+
 	page = dma_alloc_contiguous(dev, size, gfp);
 	if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
 		dma_free_contiguous(dev, page, size);
@@ -142,7 +161,7 @@ void *dma_direct_alloc(struct device *dev, size_t size,
 		gfp |= __GFP_NOWARN;
 
 	if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
-	    !force_dma_unencrypted(dev)) {
+	    !force_dma_unencrypted(dev) && !is_swiotlb_for_alloc(dev)) {
 		page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO);
 		if (!page)
 			return NULL;
@@ -157,7 +176,8 @@ void *dma_direct_alloc(struct device *dev, size_t size,
 	if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED) &&
 	    !IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
 	    !IS_ENABLED(CONFIG_DMA_GLOBAL_POOL) &&
-	    !dev_is_dma_coherent(dev))
+	    !dev_is_dma_coherent(dev) &&
+	    !is_swiotlb_for_alloc(dev))
 		return arch_dma_alloc(dev, size, dma_handle, gfp, attrs);
 
 	if (IS_ENABLED(CONFIG_DMA_GLOBAL_POOL) &&
@@ -167,11 +187,16 @@ void *dma_direct_alloc(struct device *dev, size_t size,
 	/*
 	 * Remapping or decrypting memory may block. If either is required and
 	 * we can't block, allocate the memory from the atomic pools.
+	 * If restricted DMA (i.e., is_swiotlb_for_alloc) is required, one must
+	 * set up another device coherent pool by shared-dma-pool and use
+	 * dma_alloc_from_dev_coherent instead.
 	 */
 	if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) &&
 	    !gfpflags_allow_blocking(gfp) &&
 	    (force_dma_unencrypted(dev) ||
-	     (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) && !dev_is_dma_coherent(dev))))
+	     (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
+	      !dev_is_dma_coherent(dev))) &&
+	    !is_swiotlb_for_alloc(dev))
 		return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp);
 
 	/* we always manually zero the memory once we are done */
@@ -242,7 +267,7 @@ out_encrypt_pages:
 			return NULL;
 	}
 out_free_pages:
-	dma_free_contiguous(dev, page, size);
+	__dma_direct_free_pages(dev, page, size);
 	return NULL;
 }
 
@@ -252,7 +277,7 @@ void dma_direct_free(struct device *dev, size_t size,
 	unsigned int page_order = get_order(size);
 
 	if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
-	    !force_dma_unencrypted(dev)) {
+	    !force_dma_unencrypted(dev) && !is_swiotlb_for_alloc(dev)) {
 		/* cpu_addr is a struct page cookie, not a kernel address */
 		dma_free_contiguous(dev, cpu_addr, size);
 		return;
@@ -261,7 +286,8 @@ void dma_direct_free(struct device *dev, size_t size,
 	if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED) &&
 	    !IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
 	    !IS_ENABLED(CONFIG_DMA_GLOBAL_POOL) &&
-	    !dev_is_dma_coherent(dev)) {
+	    !dev_is_dma_coherent(dev) &&
+	    !is_swiotlb_for_alloc(dev)) {
 		arch_dma_free(dev, size, cpu_addr, dma_addr, attrs);
 		return;
 	}
@@ -286,7 +312,7 @@ void dma_direct_free(struct device *dev, size_t size,
 	else if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_CLEAR_UNCACHED))
 		arch_dma_clear_uncached(cpu_addr, size);
 
-	dma_free_contiguous(dev, dma_direct_to_page(dev, dma_addr), size);
+	__dma_direct_free_pages(dev, dma_direct_to_page(dev, dma_addr), size);
 }
 
 struct page *dma_direct_alloc_pages(struct device *dev, size_t size,
@@ -296,7 +322,8 @@ struct page *dma_direct_alloc_pages(struct device *dev, size_t size,
 	void *ret;
 
 	if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) &&
-	    force_dma_unencrypted(dev) && !gfpflags_allow_blocking(gfp))
+	    force_dma_unencrypted(dev) && !gfpflags_allow_blocking(gfp) &&
+	    !is_swiotlb_for_alloc(dev))
 		return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp);
 
 	page = __dma_direct_alloc_pages(dev, size, gfp);
@@ -323,7 +350,7 @@ struct page *dma_direct_alloc_pages(struct device *dev, size_t size,
 	*dma_handle = phys_to_dma_direct(dev, page_to_phys(page));
 	return page;
 out_free_pages:
-	dma_free_contiguous(dev, page, size);
+	__dma_direct_free_pages(dev, page, size);
 	return NULL;
 }
 
@@ -342,7 +369,7 @@ void dma_direct_free_pages(struct device *dev, size_t size,
 	if (force_dma_unencrypted(dev))
 		set_memory_encrypted((unsigned long)vaddr, 1 << page_order);
 
-	dma_free_contiguous(dev, page, size);
+	__dma_direct_free_pages(dev, page, size);
 }
 
 #if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \
@@ -356,7 +383,7 @@ void dma_direct_sync_sg_for_device(struct device *dev,
 	for_each_sg(sgl, sg, nents, i) {
 		phys_addr_t paddr = dma_to_phys(dev, sg_dma_address(sg));
 
-		if (unlikely(is_swiotlb_buffer(paddr)))
+		if (unlikely(is_swiotlb_buffer(dev, paddr)))
 			swiotlb_sync_single_for_device(dev, paddr, sg->length,
 						       dir);
 
@@ -382,7 +409,7 @@ void dma_direct_sync_sg_for_cpu(struct device *dev,
 		if (!dev_is_dma_coherent(dev))
 			arch_sync_dma_for_cpu(paddr, sg->length, dir);
 
-		if (unlikely(is_swiotlb_buffer(paddr)))
+		if (unlikely(is_swiotlb_buffer(dev, paddr)))
 			swiotlb_sync_single_for_cpu(dev, paddr, sg->length,
 						    dir);
 
@@ -510,8 +537,8 @@ int dma_direct_supported(struct device *dev, u64 mask)
 size_t dma_direct_max_mapping_size(struct device *dev)
 {
 	/* If SWIOTLB is active, use its maximum mapping size */
-	if (is_swiotlb_active() &&
-	    (dma_addressing_limited(dev) || swiotlb_force == SWIOTLB_FORCE))
+	if (is_swiotlb_active(dev) &&
+	    (dma_addressing_limited(dev) || is_swiotlb_force_bounce(dev)))
 		return swiotlb_max_mapping_size(dev);
 	return SIZE_MAX;
 }
@@ -519,7 +546,7 @@ size_t dma_direct_max_mapping_size(struct device *dev)
 bool dma_direct_need_sync(struct device *dev, dma_addr_t dma_addr)
 {
 	return !dev_is_dma_coherent(dev) ||
-		is_swiotlb_buffer(dma_to_phys(dev, dma_addr));
+	       is_swiotlb_buffer(dev, dma_to_phys(dev, dma_addr));
 }
 
 /**
diff --git a/kernel/dma/direct.h b/kernel/dma/direct.h
index 50afc05b6f1d..4632b0f4f72e 100644
--- a/kernel/dma/direct.h
+++ b/kernel/dma/direct.h
@@ -56,7 +56,7 @@ static inline void dma_direct_sync_single_for_device(struct device *dev,
 {
 	phys_addr_t paddr = dma_to_phys(dev, addr);
 
-	if (unlikely(is_swiotlb_buffer(paddr)))
+	if (unlikely(is_swiotlb_buffer(dev, paddr)))
 		swiotlb_sync_single_for_device(dev, paddr, size, dir);
 
 	if (!dev_is_dma_coherent(dev))
@@ -73,7 +73,7 @@ static inline void dma_direct_sync_single_for_cpu(struct device *dev,
 		arch_sync_dma_for_cpu_all();
 	}
 
-	if (unlikely(is_swiotlb_buffer(paddr)))
+	if (unlikely(is_swiotlb_buffer(dev, paddr)))
 		swiotlb_sync_single_for_cpu(dev, paddr, size, dir);
 
 	if (dir == DMA_FROM_DEVICE)
@@ -87,7 +87,7 @@ static inline dma_addr_t dma_direct_map_page(struct device *dev,
 	phys_addr_t phys = page_to_phys(page) + offset;
 	dma_addr_t dma_addr = phys_to_dma(dev, phys);
 
-	if (unlikely(swiotlb_force == SWIOTLB_FORCE))
+	if (is_swiotlb_force_bounce(dev))
 		return swiotlb_map(dev, phys, size, dir, attrs);
 
 	if (unlikely(!dma_capable(dev, dma_addr, size, true))) {
@@ -113,7 +113,7 @@ static inline void dma_direct_unmap_page(struct device *dev, dma_addr_t addr,
 	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
 		dma_direct_sync_single_for_cpu(dev, addr, size, dir);
 
-	if (unlikely(is_swiotlb_buffer(phys)))
+	if (unlikely(is_swiotlb_buffer(dev, phys)))
 		swiotlb_tbl_unmap_single(dev, phys, size, dir, attrs);
 }
 #endif /* _KERNEL_DMA_DIRECT_H */
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index e50df8d8f87e..87c40517e822 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -39,6 +39,13 @@
 #ifdef CONFIG_DEBUG_FS
 #include <linux/debugfs.h>
 #endif
+#ifdef CONFIG_DMA_RESTRICTED_POOL
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/of_reserved_mem.h>
+#include <linux/slab.h>
+#endif
 
 #include <asm/io.h>
 #include <asm/dma.h>
@@ -63,7 +70,7 @@
 
 enum swiotlb_force swiotlb_force;
 
-struct io_tlb_mem *io_tlb_default_mem;
+struct io_tlb_mem io_tlb_default_mem;
 
 /*
  * Max segment that we can provide which (if pages are contingous) will
@@ -94,7 +101,7 @@ early_param("swiotlb", setup_io_tlb_npages);
 
 unsigned int swiotlb_max_segment(void)
 {
-	return io_tlb_default_mem ? max_segment : 0;
+	return io_tlb_default_mem.nslabs ? max_segment : 0;
 }
 EXPORT_SYMBOL_GPL(swiotlb_max_segment);
 
@@ -127,9 +134,9 @@ void __init swiotlb_adjust_size(unsigned long size)
 
 void swiotlb_print_info(void)
 {
-	struct io_tlb_mem *mem = io_tlb_default_mem;
+	struct io_tlb_mem *mem = &io_tlb_default_mem;
 
-	if (!mem) {
+	if (!mem->nslabs) {
 		pr_warn("No low mem\n");
 		return;
 	}
@@ -156,11 +163,11 @@ static inline unsigned long nr_slots(u64 val)
  */
 void __init swiotlb_update_mem_attributes(void)
 {
-	struct io_tlb_mem *mem = io_tlb_default_mem;
+	struct io_tlb_mem *mem = &io_tlb_default_mem;
 	void *vaddr;
 	unsigned long bytes;
 
-	if (!mem || mem->late_alloc)
+	if (!mem->nslabs || mem->late_alloc)
 		return;
 	vaddr = phys_to_virt(mem->start);
 	bytes = PAGE_ALIGN(mem->nslabs << IO_TLB_SHIFT);
@@ -168,36 +175,50 @@ void __init swiotlb_update_mem_attributes(void)
 	memset(vaddr, 0, bytes);
 }
 
-int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
+static void swiotlb_init_io_tlb_mem(struct io_tlb_mem *mem, phys_addr_t start,
+				    unsigned long nslabs, bool late_alloc)
 {
+	void *vaddr = phys_to_virt(start);
 	unsigned long bytes = nslabs << IO_TLB_SHIFT, i;
-	struct io_tlb_mem *mem;
-	size_t alloc_size;
-
-	if (swiotlb_force == SWIOTLB_NO_FORCE)
-		return 0;
-
-	/* protect against double initialization */
-	if (WARN_ON_ONCE(io_tlb_default_mem))
-		return -ENOMEM;
 
-	alloc_size = PAGE_ALIGN(struct_size(mem, slots, nslabs));
-	mem = memblock_alloc(alloc_size, PAGE_SIZE);
-	if (!mem)
-		panic("%s: Failed to allocate %zu bytes align=0x%lx\n",
-		      __func__, alloc_size, PAGE_SIZE);
 	mem->nslabs = nslabs;
-	mem->start = __pa(tlb);
+	mem->start = start;
 	mem->end = mem->start + bytes;
 	mem->index = 0;
+	mem->late_alloc = late_alloc;
+
+	if (swiotlb_force == SWIOTLB_FORCE)
+		mem->force_bounce = true;
+
 	spin_lock_init(&mem->lock);
 	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;
 	}
+	memset(vaddr, 0, bytes);
+}
+
+int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
+{
+	struct io_tlb_mem *mem = &io_tlb_default_mem;
+	size_t alloc_size;
+
+	if (swiotlb_force == SWIOTLB_NO_FORCE)
+		return 0;
+
+	/* protect against double initialization */
+	if (WARN_ON_ONCE(mem->nslabs))
+		return -ENOMEM;
+
+	alloc_size = PAGE_ALIGN(array_size(sizeof(*mem->slots), nslabs));
+	mem->slots = memblock_alloc(alloc_size, PAGE_SIZE);
+	if (!mem->slots)
+		panic("%s: Failed to allocate %zu bytes align=0x%lx\n",
+		      __func__, alloc_size, PAGE_SIZE);
+
+	swiotlb_init_io_tlb_mem(mem, __pa(tlb), nslabs, false);
 
-	io_tlb_default_mem = mem;
 	if (verbose)
 		swiotlb_print_info();
 	swiotlb_set_max_segment(mem->nslabs << IO_TLB_SHIFT);
@@ -282,37 +303,24 @@ swiotlb_late_init_with_default_size(size_t default_size)
 int
 swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
 {
-	unsigned long bytes = nslabs << IO_TLB_SHIFT, i;
-	struct io_tlb_mem *mem;
+	struct io_tlb_mem *mem = &io_tlb_default_mem;
+	unsigned long bytes = nslabs << IO_TLB_SHIFT;
 
 	if (swiotlb_force == SWIOTLB_NO_FORCE)
 		return 0;
 
 	/* protect against double initialization */
-	if (WARN_ON_ONCE(io_tlb_default_mem))
+	if (WARN_ON_ONCE(mem->nslabs))
 		return -ENOMEM;
 
-	mem = (void *)__get_free_pages(GFP_KERNEL,
-		get_order(struct_size(mem, slots, nslabs)));
-	if (!mem)
+	mem->slots = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
+		get_order(array_size(sizeof(*mem->slots), nslabs)));
+	if (!mem->slots)
 		return -ENOMEM;
 
-	mem->nslabs = nslabs;
-	mem->start = virt_to_phys(tlb);
-	mem->end = mem->start + bytes;
-	mem->index = 0;
-	mem->late_alloc = 1;
-	spin_lock_init(&mem->lock);
-	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;
-	}
-
 	set_memory_decrypted((unsigned long)tlb, bytes >> PAGE_SHIFT);
-	memset(tlb, 0, bytes);
+	swiotlb_init_io_tlb_mem(mem, virt_to_phys(tlb), nslabs, true);
 
-	io_tlb_default_mem = mem;
 	swiotlb_print_info();
 	swiotlb_set_max_segment(mem->nslabs << IO_TLB_SHIFT);
 	return 0;
@@ -320,18 +328,28 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
 
 void __init swiotlb_exit(void)
 {
-	struct io_tlb_mem *mem = io_tlb_default_mem;
-	size_t size;
+	struct io_tlb_mem *mem = &io_tlb_default_mem;
+	unsigned long tbl_vaddr;
+	size_t tbl_size, slots_size;
 
-	if (!mem)
+	if (!mem->nslabs)
 		return;
 
-	size = struct_size(mem, slots, mem->nslabs);
-	if (mem->late_alloc)
-		free_pages((unsigned long)mem, get_order(size));
-	else
-		memblock_free_late(__pa(mem), PAGE_ALIGN(size));
-	io_tlb_default_mem = NULL;
+	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) {
+		free_pages(tbl_vaddr, get_order(tbl_size));
+		free_pages((unsigned long)mem->slots, get_order(slots_size));
+	} else {
+		memblock_free_late(mem->start, tbl_size);
+		memblock_free_late(__pa(mem->slots), slots_size);
+	}
+
+	memset(mem, 0, sizeof(*mem));
 }
 
 /*
@@ -348,19 +366,33 @@ static unsigned int swiotlb_align_offset(struct device *dev, u64 addr)
 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 = io_tlb_default_mem;
+	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 = phys_to_virt(tlb_addr);
-	unsigned int tlb_offset;
+	unsigned int tlb_offset, orig_addr_offset;
 
 	if (orig_addr == INVALID_PHYS_ADDR)
 		return;
 
-	tlb_offset = (tlb_addr & (IO_TLB_SIZE - 1)) -
-		     swiotlb_align_offset(dev, orig_addr);
+	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;
@@ -426,10 +458,10 @@ static unsigned int wrap_index(struct io_tlb_mem *mem, unsigned int 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 find_slots(struct device *dev, phys_addr_t orig_addr,
-		size_t alloc_size)
+static int swiotlb_find_slots(struct device *dev, phys_addr_t orig_addr,
+			      size_t alloc_size)
 {
-	struct io_tlb_mem *mem = io_tlb_default_mem;
+	struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
 	unsigned long boundary_mask = dma_get_seg_boundary(dev);
 	dma_addr_t tbl_dma_addr =
 		phys_to_dma_unencrypted(dev, mem->start) & boundary_mask;
@@ -438,6 +470,7 @@ static int find_slots(struct device *dev, phys_addr_t orig_addr,
 		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;
 
 	BUG_ON(!nslots);
@@ -457,8 +490,9 @@ static int find_slots(struct device *dev, phys_addr_t orig_addr,
 
 	index = wrap = wrap_index(mem, ALIGN(mem->index, stride));
 	do {
-		if ((slot_addr(tbl_dma_addr, index) & iotlb_align_mask) !=
-		    (orig_addr & iotlb_align_mask)) {
+		if (orig_addr &&
+		    (slot_addr(tbl_dma_addr, index) & iotlb_align_mask) !=
+			    (orig_addr & iotlb_align_mask)) {
 			index = wrap_index(mem, index + 1);
 			continue;
 		}
@@ -482,8 +516,11 @@ not_found:
 	return -1;
 
 found:
-	for (i = index; i < index + nslots; i++)
+	for (i = index; i < index + nslots; i++) {
 		mem->slots[i].list = 0;
+		mem->slots[i].alloc_size =
+			alloc_size - (offset + ((i - index) << IO_TLB_SHIFT));
+	}
 	for (i = index - 1;
 	     io_tlb_offset(i) != IO_TLB_SEGSIZE - 1 &&
 	     mem->slots[i].list; i--)
@@ -506,7 +543,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr,
 		size_t mapping_size, size_t alloc_size,
 		enum dma_data_direction dir, unsigned long attrs)
 {
-	struct io_tlb_mem *mem = io_tlb_default_mem;
+	struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
 	unsigned int offset = swiotlb_align_offset(dev, orig_addr);
 	unsigned int i;
 	int index;
@@ -524,7 +561,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr,
 		return (phys_addr_t)DMA_MAPPING_ERROR;
 	}
 
-	index = find_slots(dev, orig_addr, alloc_size + offset);
+	index = swiotlb_find_slots(dev, orig_addr, alloc_size + offset);
 	if (index == -1) {
 		if (!(attrs & DMA_ATTR_NO_WARN))
 			dev_warn_ratelimited(dev,
@@ -538,11 +575,8 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr,
 	 * 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++) {
+	for (i = 0; i < nr_slots(alloc_size + offset); i++)
 		mem->slots[index + i].orig_addr = slot_addr(orig_addr, i);
-		mem->slots[index + i].alloc_size =
-			alloc_size - (i << IO_TLB_SHIFT);
-	}
 	tlb_addr = slot_addr(mem->start, index) + offset;
 	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
 	    (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
@@ -550,28 +584,16 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr,
 	return tlb_addr;
 }
 
-/*
- * tlb_addr is the physical address of the bounce buffer to unmap.
- */
-void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
-			      size_t mapping_size, enum dma_data_direction dir,
-			      unsigned long attrs)
+static void swiotlb_release_slots(struct device *dev, phys_addr_t tlb_addr)
 {
-	struct io_tlb_mem *mem = io_tlb_default_mem;
+	struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
 	unsigned long flags;
-	unsigned int offset = swiotlb_align_offset(hwdev, tlb_addr);
+	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 count, i;
 
 	/*
-	 * First, sync the memory before unmapping the entry
-	 */
-	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
-	    (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL))
-		swiotlb_bounce(hwdev, tlb_addr, mapping_size, DMA_FROM_DEVICE);
-
-	/*
 	 * 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
@@ -605,6 +627,23 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
 	spin_unlock_irqrestore(&mem->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)
 {
@@ -662,26 +701,155 @@ size_t swiotlb_max_mapping_size(struct device *dev)
 	return ((size_t)IO_TLB_SIZE) * IO_TLB_SEGSIZE;
 }
 
-bool is_swiotlb_active(void)
+bool is_swiotlb_active(struct device *dev)
 {
-	return io_tlb_default_mem != NULL;
+	struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
+
+	return mem && mem->nslabs;
 }
 EXPORT_SYMBOL_GPL(is_swiotlb_active);
 
 #ifdef CONFIG_DEBUG_FS
+static struct dentry *debugfs_dir;
 
-static int __init swiotlb_create_debugfs(void)
+static void swiotlb_create_debugfs_files(struct io_tlb_mem *mem)
 {
-	struct io_tlb_mem *mem = io_tlb_default_mem;
-
-	if (!mem)
-		return 0;
-	mem->debugfs = debugfs_create_dir("swiotlb", NULL);
 	debugfs_create_ulong("io_tlb_nslabs", 0400, mem->debugfs, &mem->nslabs);
 	debugfs_create_ulong("io_tlb_used", 0400, mem->debugfs, &mem->used);
+}
+
+static int __init swiotlb_create_default_debugfs(void)
+{
+	struct io_tlb_mem *mem = &io_tlb_default_mem;
+
+	debugfs_dir = debugfs_create_dir("swiotlb", NULL);
+	if (mem->nslabs) {
+		mem->debugfs = debugfs_dir;
+		swiotlb_create_debugfs_files(mem);
+	}
 	return 0;
 }
 
-late_initcall(swiotlb_create_debugfs);
+late_initcall(swiotlb_create_default_debugfs);
+
+#endif
 
+#ifdef CONFIG_DMA_RESTRICTED_POOL
+
+#ifdef CONFIG_DEBUG_FS
+static void rmem_swiotlb_debugfs_init(struct reserved_mem *rmem)
+{
+	struct io_tlb_mem *mem = rmem->priv;
+
+	mem->debugfs = debugfs_create_dir(rmem->name, debugfs_dir);
+	swiotlb_create_debugfs_files(mem);
+}
+#else
+static void rmem_swiotlb_debugfs_init(struct reserved_mem *rmem)
+{
+}
 #endif
+
+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);
+	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;
+
+	/*
+	 * 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 = kzalloc(array_size(sizeof(*mem->slots), nslabs),
+				     GFP_KERNEL);
+		if (!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, false);
+		mem->force_bounce = true;
+		mem->for_alloc = true;
+
+		rmem->priv = mem;
+
+		rmem_swiotlb_debugfs_init(rmem);
+	}
+
+	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;
+
+	if (PageHighMem(pfn_to_page(PHYS_PFN(rmem->base)))) {
+		pr_err("Restricted DMA pool must be accessible within the linear mapping.");
+		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 */