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SubjectRe: [PATCH 11/21] dma-iommu: refactor page array remap helpers
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On 27/03/2019 08:04, Christoph Hellwig wrote:
> Move the call to dma_common_pages_remap / dma_common_free_remap into
> __iommu_dma_alloc / __iommu_dma_free and rename those functions to
> better describe what they do. This keeps the functionality that
> allocates and remaps a non-contigous array of pages nicely abstracted
> out from the calling code.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> drivers/iommu/dma-iommu.c | 75 +++++++++++++++++++--------------------
> 1 file changed, 36 insertions(+), 39 deletions(-)
>
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index 4d46beeea5b7..2013c650718a 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -524,51 +524,57 @@ static struct page **__iommu_dma_alloc_pages(struct device *dev,
> }
>
> /**
> - * iommu_dma_free - Free a buffer allocated by __iommu_dma_alloc()
> + * iommu_dma_free_remap - Free a buffer allocated by iommu_dma_alloc_remap

Unmap and free a buffer allocated by iommu_dma_alloc_remap()

> * @dev: Device which owns this buffer
> - * @pages: Array of buffer pages as returned by __iommu_dma_alloc()
> * @size: Size of buffer in bytes
> + * @cpu_address: Virtual address of the buffer
> * @handle: DMA address of buffer

@dma_handle

> *
> * Frees both the pages associated with the buffer, and the array
> * describing them

and removes the CPU mapping.

> */
> -static void __iommu_dma_free(struct device *dev, struct page **pages,
> - size_t size, dma_addr_t *handle)
> +static void iommu_dma_free_remap(struct device *dev, size_t size,
> + void *cpu_addr, dma_addr_t dma_handle)
> {
> - __iommu_dma_unmap(iommu_get_dma_domain(dev), *handle, size);
> - __iommu_dma_free_pages(pages, PAGE_ALIGN(size) >> PAGE_SHIFT);
> - *handle = DMA_MAPPING_ERROR;
> + struct vm_struct *area = find_vm_area(cpu_addr);
> +
> + if (WARN_ON(!area || !area->pages))
> + return;
> + __iommu_dma_unmap(iommu_get_dma_domain(dev), dma_handle, size);
> + __iommu_dma_free_pages(area->pages, PAGE_ALIGN(size) >> PAGE_SHIFT);
> + dma_common_free_remap(cpu_addr, PAGE_ALIGN(size), VM_USERMAP);
> }
>
> /**
> - * __iommu_dma_alloc - Allocate and map a buffer contiguous in IOVA space
> + * iommu_dma_alloc_remap - Allocate and map a buffer contiguous in IOVA space

I'm not sure of a succinct way to update that one :(

Other than kerneldoc nits, though,

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> * @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
> * @attrs: DMA attributes for this allocation
> - * @prot: IOMMU mapping flags
> - * @handle: Out argument for allocated DMA handle
> *
> * 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: Array of struct page pointers describing the buffer,
> - * or NULL on failure.
> + * Return: Mapped virtual address, or NULL on failure.
> */
> -static struct page **__iommu_dma_alloc(struct device *dev, size_t size,
> - gfp_t gfp, unsigned long attrs, int prot, dma_addr_t *handle)
> +static void *iommu_dma_alloc_remap(struct device *dev, size_t size,
> + dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
> {
> struct iommu_domain *domain = iommu_get_dma_domain(dev);
> struct iommu_dma_cookie *cookie = domain->iova_cookie;
> struct iova_domain *iovad = &cookie->iovad;
> + bool coherent = dev_is_dma_coherent(dev);
> + int ioprot = dma_info_to_prot(DMA_BIDIRECTIONAL, coherent, attrs);
> + pgprot_t prot = arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs);
> + unsigned int count, min_size, alloc_sizes = domain->pgsize_bitmap;
> struct page **pages;
> struct sg_table sgt;
> dma_addr_t iova;
> - unsigned int count, min_size, alloc_sizes = domain->pgsize_bitmap;
> + void *vaddr;
>
> - *handle = DMA_MAPPING_ERROR;
> + *dma_handle = DMA_MAPPING_ERROR;
>
> min_size = alloc_sizes & -alloc_sizes;
> if (min_size < PAGE_SIZE) {
> @@ -594,7 +600,7 @@ static struct page **__iommu_dma_alloc(struct device *dev, size_t size,
> if (sg_alloc_table_from_pages(&sgt, pages, count, 0, size, GFP_KERNEL))
> goto out_free_iova;
>
> - if (!(prot & IOMMU_CACHE)) {
> + if (!(ioprot & IOMMU_CACHE)) {
> struct scatterlist *sg;
> int i;
>
> @@ -602,14 +608,21 @@ static struct page **__iommu_dma_alloc(struct device *dev, size_t size,
> arch_dma_prep_coherent(sg_page(sg), sg->length);
> }
>
> - if (iommu_map_sg(domain, iova, sgt.sgl, sgt.orig_nents, prot)
> + if (iommu_map_sg(domain, iova, sgt.sgl, sgt.orig_nents, ioprot)
> < size)
> goto out_free_sg;
>
> - *handle = iova;
> + vaddr = dma_common_pages_remap(pages, size, VM_USERMAP, prot,
> + __builtin_return_address(0));
> + if (!vaddr)
> + goto out_unmap;
> +
> + *dma_handle = iova;
> sg_free_table(&sgt);
> - return pages;
> + return vaddr;
>
> +out_unmap:
> + __iommu_dma_unmap(domain, iova, size);
> out_free_sg:
> sg_free_table(&sgt);
> out_free_iova:
> @@ -1013,18 +1026,7 @@ static void *iommu_dma_alloc(struct device *dev, size_t size,
> size >> PAGE_SHIFT);
> }
> } else {
> - pgprot_t prot = arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs);
> - struct page **pages;
> -
> - pages = __iommu_dma_alloc(dev, iosize, gfp, attrs, ioprot,
> - handle);
> - if (!pages)
> - return NULL;
> -
> - addr = dma_common_pages_remap(pages, size, VM_USERMAP, prot,
> - __builtin_return_address(0));
> - if (!addr)
> - __iommu_dma_free(dev, pages, iosize, handle);
> + addr = iommu_dma_alloc_remap(dev, iosize, handle, gfp, attrs);
> }
> return addr;
> }
> @@ -1038,7 +1040,7 @@ static void iommu_dma_free(struct device *dev, size_t size, void *cpu_addr,
> /*
> * @cpu_addr will be one of 4 things depending on how it was allocated:
> * - A remapped array of pages for contiguous allocations.
> - * - A remapped array of pages from __iommu_dma_alloc(), for all
> + * - A remapped array of pages from iommu_dma_alloc_remap(), for all
> * non-atomic allocations.
> * - A non-cacheable alias from the atomic pool, for atomic
> * allocations by non-coherent devices.
> @@ -1056,12 +1058,7 @@ static void iommu_dma_free(struct device *dev, size_t size, void *cpu_addr,
> dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT);
> dma_common_free_remap(cpu_addr, size, VM_USERMAP);
> } else if (is_vmalloc_addr(cpu_addr)){
> - struct vm_struct *area = find_vm_area(cpu_addr);
> -
> - if (WARN_ON(!area || !area->pages))
> - return;
> - __iommu_dma_free(dev, area->pages, iosize, &handle);
> - dma_common_free_remap(cpu_addr, size, VM_USERMAP);
> + iommu_dma_free_remap(dev, iosize, cpu_addr, handle);
> } else {
> __iommu_dma_unmap_page(dev, handle, iosize, 0, 0);
> __free_pages(virt_to_page(cpu_addr), get_order(size));
>

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