swiotlb: Support aligned swiotlb buffers

Add an argument to swiotlb_tbl_map_single that specifies the desired
alignment of the allocated buffer. This is used by dma-iommu to ensure
the buffer is aligned to the iova granule size when using swiotlb with
untrusted sub-granule mappings. This addresses an issue where adjacent
slots could be exposed to the untrusted device if IO_TLB_SIZE < iova
granule < PAGE_SIZE.

Signed-off-by: David Stevens <stevensd@chromium.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210929023300.335969-7-stevensd@google.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 85a005b268f673863ace864a3c11a134d90064a5..289c49ead01a90933858c967638a739d075bd931 100644 (file)
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -818,8 +818,8 @@ static dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
                size_t padding_size;
 
                aligned_size = iova_align(iovad, size);
-               phys = swiotlb_tbl_map_single(dev, phys, size,
-                                             aligned_size, dir, attrs);
+               phys = swiotlb_tbl_map_single(dev, phys, size, aligned_size,
+                                             iova_mask(iovad), dir, attrs);
 
                if (phys == DMA_MAPPING_ERROR)
                        return DMA_MAPPING_ERROR;

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index e56a5faac395c6684413d7d0047d2a2ae9714a6d..cbdff89799807085ebfac1810d132a8aa55719cb 100644 (file)
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -380,7 +380,7 @@ static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
         */
        trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force);
 
-       map = swiotlb_tbl_map_single(dev, phys, size, size, dir, attrs);
+       map = swiotlb_tbl_map_single(dev, phys, size, size, 0, dir, attrs);
        if (map == (phys_addr_t)DMA_MAPPING_ERROR)
                return DMA_MAPPING_ERROR;
 

diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index b0cb2a9973f4955b9385d2f0a60d5a76f235ee28..569272871375c446dc3bbb2fed26a1fcb10f8c3e 100644 (file)
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -45,7 +45,8 @@ extern void __init swiotlb_update_mem_attributes(void);
 
 phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t phys,
                size_t mapping_size, size_t alloc_size,
-               enum dma_data_direction dir, unsigned long attrs);
+               unsigned int alloc_aligned_mask, enum dma_data_direction dir,
+               unsigned long attrs);
 
 extern void swiotlb_tbl_unmap_single(struct device *hwdev,
                                     phys_addr_t tlb_addr,

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 87c40517e82274718bd77e16cbf10f736299abb4..019672b3da1d3c0ce08745fea92d17edf2f1b06f 100644 (file)
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -459,7 +459,7 @@ static unsigned int wrap_index(struct io_tlb_mem *mem, unsigned int index)
  * allocate a buffer from that IO TLB pool.
  */
 static int swiotlb_find_slots(struct device *dev, phys_addr_t orig_addr,
-                             size_t alloc_size)
+                             size_t alloc_size, unsigned int alloc_align_mask)
 {
        struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
        unsigned long boundary_mask = dma_get_seg_boundary(dev);
@@ -483,6 +483,7 @@ static int swiotlb_find_slots(struct device *dev, phys_addr_t orig_addr,
        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(&mem->lock, flags);
        if (unlikely(nslots > mem->nslabs - mem->used))
@@ -541,7 +542,8 @@ found:
 
 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)
+               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);
@@ -561,7 +563,8 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr,
                return (phys_addr_t)DMA_MAPPING_ERROR;
        }
 
-       index = swiotlb_find_slots(dev, orig_addr, alloc_size + offset);
+       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,
@@ -675,7 +678,7 @@ dma_addr_t swiotlb_map(struct device *dev, phys_addr_t paddr, size_t size,
        trace_swiotlb_bounced(dev, phys_to_dma(dev, paddr), size,
                              swiotlb_force);
 
-       swiotlb_addr = swiotlb_tbl_map_single(dev, paddr, size, size, dir,
+       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;
@@ -759,7 +762,7 @@ struct page *swiotlb_alloc(struct device *dev, size_t size)
        if (!mem)
                return NULL;
 
-       index = swiotlb_find_slots(dev, 0, size);
+       index = swiotlb_find_slots(dev, 0, size, 0);
        if (index == -1)
                return NULL;