swiotlb: use coherent_dma_mask in alloc_coherent

Impact: fix DMA buffer allocation coherency bug in certain configs

This patch fixes swiotlb to use dev->coherent_dma_mask in
swiotlb_alloc_coherent().

coherent_dma_mask is a subset of dma_mask (equal to it most of
the time), enumerating the address range that a given device
is able to DMA to/from in a cache-coherent way.

But currently, swiotlb uses dev->dma_mask in alloc_coherent()
implicitly via address_needs_mapping(), but alloc_coherent is really
supposed to use coherent_dma_mask.

This bug could break drivers that uses smaller coherent_dma_mask than
dma_mask (though the current code works for the majority that use the
same mask for coherent_dma_mask and dma_mask).

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: tony.luck@intel.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 7 insertions, 3 deletions

diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 78330c37a61b..5f6c629a924d 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -467,9 +467,13 @@ swiotlb_alloc_coherent(struct device *hwdev, size_t size,
         dma_addr_t dev_addr;
         void *ret;
         int order = get_order(size);
+        u64 dma_mask = DMA_32BIT_MASK;
+
+        if (hwdev && hwdev->coherent_dma_mask)
+                dma_mask = hwdev->coherent_dma_mask;
 
         ret = (void *)__get_free_pages(flags, order);
-        if (ret && address_needs_mapping(hwdev, virt_to_bus(ret), size)) {
+        if (ret && !is_buffer_dma_capable(dma_mask, virt_to_bus(ret), size)) {
                 /*
                  * The allocated memory isn't reachable by the device.
                  * Fall back on swiotlb_map_single().
@@ -493,9 +497,9 @@ swiotlb_alloc_coherent(struct device *hwdev, size_t size,
         dev_addr = virt_to_bus(ret);
 
         /* Confirm address can be DMA'd by device */
-        if (address_needs_mapping(hwdev, dev_addr, size)) {
+        if (!is_buffer_dma_capable(dma_mask, dev_addr, size)) {
                 printk("hwdev DMA mask = 0x%016Lx, dev_addr = 0x%016Lx\n",
-                       (unsigned long long)*hwdev->dma_mask,
+                       (unsigned long long)dma_mask,
                        (unsigned long long)dev_addr);
 
                 /* DMA_TO_DEVICE to avoid memcpy in unmap_single */