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From:   Claire Chang <tientzu@chromium.org>
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        drinkcat@chromium.org, Claire Chang <tientzu@chromium.org>
Subject: [RFC PATCH v3 4/6] swiotlb: Add restricted DMA alloc/free support.
Date:   Wed,  6 Jan 2021 11:41:22 +0800
Message-Id: <20210106034124.30560-5-tientzu@chromium.org>
In-Reply-To: <20210106034124.30560-1-tientzu@chromium.org>
References: <20210106034124.30560-1-tientzu@chromium.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Add the functions, swiotlb_alloc and swiotlb_free to support the
memory allocation from restricted DMA pool.

Signed-off-by: Claire Chang <tientzu@chromium.org>
---
 include/linux/swiotlb.h |   6 ++
 kernel/dma/direct.c     |  12 +++
 kernel/dma/swiotlb.c    | 171 +++++++++++++++++++++++++++++-----------
 3 files changed, 144 insertions(+), 45 deletions(-)

diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 5135e5636042..84fe96e40685 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -68,6 +68,12 @@ extern void swiotlb_tbl_sync_single(struct device *hwdev,
 dma_addr_t swiotlb_map(struct device *dev, phys_addr_t phys,
 		size_t size, enum dma_data_direction dir, unsigned long attrs);
 
+void *swiotlb_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
+		    unsigned long attrs);
+
+void swiotlb_free(struct device *dev, size_t size, void *vaddr,
+		  dma_addr_t dma_addr, unsigned long attrs);
+
 #ifdef CONFIG_SWIOTLB
 extern enum swiotlb_force swiotlb_force;
 
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 30ccbc08e229..126e9b3354d6 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -137,6 +137,11 @@ void *dma_direct_alloc(struct device *dev, size_t size,
 	void *ret;
 	int err;
 
+#ifdef CONFIG_SWIOTLB
+	if (unlikely(dev->dma_io_tlb_mem))
+		return swiotlb_alloc(dev, size, dma_handle, attrs);
+#endif
+
 	size = PAGE_ALIGN(size);
 	if (attrs & DMA_ATTR_NO_WARN)
 		gfp |= __GFP_NOWARN;
@@ -246,6 +251,13 @@ void dma_direct_free(struct device *dev, size_t size,
 {
 	unsigned int page_order = get_order(size);
 
+#ifdef CONFIG_SWIOTLB
+	if (unlikely(dev->dma_io_tlb_mem)) {
+		swiotlb_free(dev, size, cpu_addr, dma_addr, attrs);
+		return;
+	}
+#endif
+
 	if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
 	    !force_dma_unencrypted(dev)) {
 		/* cpu_addr is a struct page cookie, not a kernel address */
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 1f05af09e61a..ca88ef59435d 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -459,14 +459,13 @@ static void swiotlb_bounce(phys_addr_t orig_addr, phys_addr_t tlb_addr,
 	}
 }
 
-phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t orig_addr,
-		size_t mapping_size, size_t alloc_size,
-		enum dma_data_direction dir, unsigned long attrs)
+static int swiotlb_tbl_find_free_region(struct device *hwdev,
+					dma_addr_t tbl_dma_addr,
+					size_t alloc_size,
+					unsigned long attrs)
 {
 	struct io_tlb_mem *mem = get_io_tlb_mem(hwdev);
-	dma_addr_t tbl_dma_addr = phys_to_dma_unencrypted(hwdev, mem->start);
 	unsigned long flags;
-	phys_addr_t tlb_addr;
 	unsigned int nslots, stride, index, wrap;
 	int i;
 	unsigned long mask;
@@ -477,15 +476,6 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t orig_addr,
 	if (no_iotlb_memory && !hwdev->dma_io_tlb_mem)
 		panic("Can not allocate SWIOTLB buffer earlier and can't now provide you with the DMA bounce buffer");
 
-	if (mem_encrypt_active())
-		pr_warn_once("Memory encryption is active and system is using DMA bounce buffers\n");
-
-	if (mapping_size > alloc_size) {
-		dev_warn_once(hwdev, "Invalid sizes (mapping: %zd bytes, alloc: %zd bytes)",
-			      mapping_size, alloc_size);
-		return (phys_addr_t)DMA_MAPPING_ERROR;
-	}
-
 	mask = dma_get_seg_boundary(hwdev);
 
 	tbl_dma_addr &= mask;
@@ -547,7 +537,6 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t orig_addr,
 				mem->list[i] = 0;
 			for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE - 1) && mem->list[i]; i--)
 				mem->list[i] = ++count;
-			tlb_addr = mem->start + (index << IO_TLB_SHIFT);
 
 			/*
 			 * Update the indices to avoid searching in the next
@@ -570,45 +559,21 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t orig_addr,
 	if (!(attrs & DMA_ATTR_NO_WARN) && printk_ratelimit())
 		dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes), total %lu (slots), used %lu (slots)\n",
 			 alloc_size, mem->nslabs, tmp_io_tlb_used);
-	return (phys_addr_t)DMA_MAPPING_ERROR;
+	return -ENOMEM;
+
 found:
 	mem->used += nslots;
 	spin_unlock_irqrestore(&mem->lock, flags);
 
-	/*
-	 * 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 < nslots; i++)
-		mem->orig_addr[index+i] = orig_addr + (i << IO_TLB_SHIFT);
-	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
-	    (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
-		swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_TO_DEVICE);
-
-	return tlb_addr;
+	return index;
 }
 
-/*
- * 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, size_t alloc_size,
-			      enum dma_data_direction dir, unsigned long attrs)
+static void swiotlb_tbl_release_region(struct device *hwdev, int index,
+				       size_t size)
 {
 	struct io_tlb_mem *mem = get_io_tlb_mem(hwdev);
 	unsigned long flags;
-	int i, count, nslots = ALIGN(alloc_size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
-	int index = (tlb_addr - mem->start) >> IO_TLB_SHIFT;
-	phys_addr_t orig_addr = mem->orig_addr[index];
-
-	/*
-	 * First, sync the memory before unmapping the entry
-	 */
-	if (orig_addr != INVALID_PHYS_ADDR &&
-	    !(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
-	    ((dir == DMA_FROM_DEVICE) || (dir == DMA_BIDIRECTIONAL)))
-		swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_FROM_DEVICE);
+	int i, count, nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
 
 	/*
 	 * Return the buffer to the free list by setting the corresponding
@@ -640,6 +605,69 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
 	spin_unlock_irqrestore(&mem->lock, flags);
 }
 
+phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, 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 = get_io_tlb_mem(hwdev);
+	dma_addr_t tbl_dma_addr = phys_to_dma_unencrypted(hwdev, mem->start);
+	phys_addr_t tlb_addr;
+	unsigned int nslots, index;
+	int i;
+
+	if (mem_encrypt_active())
+		pr_warn_once("Memory encryption is active and system is using DMA bounce buffers\n");
+
+	if (mapping_size > alloc_size) {
+		dev_warn_once(hwdev, "Invalid sizes (mapping: %zd bytes, alloc: %zd bytes)",
+			      mapping_size, alloc_size);
+		return (phys_addr_t)DMA_MAPPING_ERROR;
+	}
+
+	index = swiotlb_tbl_find_free_region(hwdev, tbl_dma_addr, alloc_size,
+					     attrs);
+	if (index < 0)
+		return (phys_addr_t)DMA_MAPPING_ERROR;
+
+	tlb_addr = mem->start + (index << IO_TLB_SHIFT);
+
+	/*
+	 * 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.
+	 */
+	nslots = ALIGN(alloc_size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
+	for (i = 0; i < nslots; i++)
+		mem->orig_addr[index+i] = orig_addr + (i << IO_TLB_SHIFT);
+	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
+	    (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
+		swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_TO_DEVICE);
+
+	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, size_t alloc_size,
+			      enum dma_data_direction dir, unsigned long attrs)
+{
+	struct io_tlb_mem *mem = get_io_tlb_mem(hwdev);
+	int index = (tlb_addr - mem->start) >> IO_TLB_SHIFT;
+	phys_addr_t orig_addr = mem->orig_addr[index];
+
+	/*
+	 * First, sync the memory before unmapping the entry
+	 */
+	if (orig_addr != INVALID_PHYS_ADDR &&
+	    !(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
+	    ((dir == DMA_FROM_DEVICE) || (dir == DMA_BIDIRECTIONAL)))
+		swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_FROM_DEVICE);
+
+	swiotlb_tbl_release_region(hwdev, index, alloc_size);
+}
+
 void swiotlb_tbl_sync_single(struct device *hwdev, phys_addr_t tlb_addr,
 			     size_t size, enum dma_data_direction dir,
 			     enum dma_sync_target target)
@@ -706,6 +734,59 @@ dma_addr_t swiotlb_map(struct device *dev, phys_addr_t paddr, size_t size,
 	return dma_addr;
 }
 
+void *swiotlb_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
+		    unsigned long attrs)
+{
+	struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
+	int index;
+	void *vaddr;
+	phys_addr_t tlb_addr;
+
+	size = PAGE_ALIGN(size);
+	index = swiotlb_tbl_find_free_region(dev, mem->start, size, attrs);
+	if (index < 0)
+		return NULL;
+
+	tlb_addr = mem->start + (index << IO_TLB_SHIFT);
+	*dma_handle = phys_to_dma_unencrypted(dev, tlb_addr);
+
+	if (!dev_is_dma_coherent(dev)) {
+		unsigned long pfn = PFN_DOWN(tlb_addr);
+
+		/* remove any dirty cache lines on the kernel alias */
+		arch_dma_prep_coherent(pfn_to_page(pfn), size);
+
+		/* create a coherent mapping */
+		vaddr = dma_common_contiguous_remap(
+			pfn_to_page(pfn), size,
+			dma_pgprot(dev, PAGE_KERNEL, attrs),
+			__builtin_return_address(0));
+		if (!vaddr) {
+			swiotlb_tbl_release_region(dev, index, size);
+			return NULL;
+		}
+	} else {
+		vaddr = phys_to_virt(tlb_addr);
+	}
+
+	memset(vaddr, 0, size);
+
+	return vaddr;
+}
+
+void swiotlb_free(struct device *dev, size_t size, void *vaddr,
+		  dma_addr_t dma_addr, unsigned long attrs)
+{
+	struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
+	unsigned int index;
+
+	if (!dev_is_dma_coherent(dev))
+		vunmap(vaddr);
+
+	index = (dma_addr - mem->start) >> IO_TLB_SHIFT;
+	swiotlb_tbl_release_region(dev, index, PAGE_ALIGN(size));
+}
+
 size_t swiotlb_max_mapping_size(struct device *dev)
 {
 	return ((size_t)1 << IO_TLB_SHIFT) * IO_TLB_SEGSIZE;
-- 
2.29.2.729.g45daf8777d-goog