dma-iommu: refactor iommu_dma_alloc_remap

Split out a new helper that only allocates a sg_table worth of
memory without mapping it into contiguous kernel address space.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Tested-by: Ricardo Ribalda <ribalda@chromium.org>

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index af765c8..ec1abad 100644 (file)
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -650,23 +650,12 @@ static struct page **__iommu_dma_alloc_pages(struct device *dev,
        return pages;
 }
 
-/**
- * iommu_dma_alloc_remap - Allocate and map a buffer contiguous in IOVA space
- * @dev: Device to allocate memory for. Must be a real device
- *      attached to an iommu_dma_domain
- * @size: Size of buffer in bytes
- * @dma_handle: Out argument for allocated DMA handle
- * @gfp: Allocation flags
- * @prot: pgprot_t to use for the remapped mapping
- * @attrs: DMA attributes for this allocation
- *
- * If @size is less than PAGE_SIZE, then a full CPU page will be allocated,
+/*
+ * If size is less than PAGE_SIZE, then a full CPU page will be allocated,
  * but an IOMMU which supports smaller pages might not map the whole thing.
- *
- * Return: Mapped virtual address, or NULL on failure.
  */
-static void *iommu_dma_alloc_remap(struct device *dev, size_t size,
-               dma_addr_t *dma_handle, gfp_t gfp, pgprot_t prot,
+static struct page **__iommu_dma_alloc_noncontiguous(struct device *dev,
+               size_t size, struct sg_table *sgt, gfp_t gfp, pgprot_t prot,
                unsigned long attrs)
 {
        struct iommu_domain *domain = iommu_get_dma_domain(dev);
@@ -676,11 +665,7 @@ static void *iommu_dma_alloc_remap(struct device *dev, size_t size,
        int ioprot = dma_info_to_prot(DMA_BIDIRECTIONAL, coherent, attrs);
        unsigned int count, min_size, alloc_sizes = domain->pgsize_bitmap;
        struct page **pages;
-       struct sg_table sgt;
        dma_addr_t iova;
-       void *vaddr;
-
-       *dma_handle = DMA_MAPPING_ERROR;
 
        if (static_branch_unlikely(&iommu_deferred_attach_enabled) &&
            iommu_deferred_attach(dev, domain))
@@ -707,38 +692,56 @@ static void *iommu_dma_alloc_remap(struct device *dev, size_t size,
        if (!iova)
                goto out_free_pages;
 
-       if (sg_alloc_table_from_pages(&sgt, pages, count, 0, size, GFP_KERNEL))
+       if (sg_alloc_table_from_pages(sgt, pages, count, 0, size, GFP_KERNEL))
                goto out_free_iova;
 
        if (!(ioprot & IOMMU_CACHE)) {
                struct scatterlist *sg;
                int i;
 
-               for_each_sg(sgt.sgl, sg, sgt.orig_nents, i)
+               for_each_sg(sgt->sgl, sg, sgt->orig_nents, i)
                        arch_dma_prep_coherent(sg_page(sg), sg->length);
        }
 
-       if (iommu_map_sg_atomic(domain, iova, sgt.sgl, sgt.orig_nents, ioprot)
+       if (iommu_map_sg_atomic(domain, iova, sgt->sgl, sgt->orig_nents, ioprot)
                        < size)
                goto out_free_sg;
 
+       sgt->sgl->dma_address = iova;
+       return pages;
+
+out_free_sg:
+       sg_free_table(sgt);
+out_free_iova:
+       iommu_dma_free_iova(cookie, iova, size, NULL);
+out_free_pages:
+       __iommu_dma_free_pages(pages, count);
+       return NULL;
+}
+
+static void *iommu_dma_alloc_remap(struct device *dev, size_t size,
+               dma_addr_t *dma_handle, gfp_t gfp, pgprot_t prot,
+               unsigned long attrs)
+{
+       struct page **pages;
+       struct sg_table sgt;
+       void *vaddr;
+
+       pages = __iommu_dma_alloc_noncontiguous(dev, size, &sgt, gfp, prot,
+                                               attrs);
+       if (!pages)
+               return NULL;
+       *dma_handle = sgt.sgl->dma_address;
+       sg_free_table(&sgt);
        vaddr = dma_common_pages_remap(pages, size, prot,
                        __builtin_return_address(0));
        if (!vaddr)
                goto out_unmap;
-
-       *dma_handle = iova;
-       sg_free_table(&sgt);
        return vaddr;
 
 out_unmap:
-       __iommu_dma_unmap(dev, iova, size);
-out_free_sg:
-       sg_free_table(&sgt);
-out_free_iova:
-       iommu_dma_free_iova(cookie, iova, size, NULL);
-out_free_pages:
-       __iommu_dma_free_pages(pages, count);
+       __iommu_dma_unmap(dev, *dma_handle, size);
+       __iommu_dma_free_pages(pages, PAGE_ALIGN(size) >> PAGE_SHIFT);
        return NULL;
 }