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SubjectRe: [PATCH 1/9] dma-direct: provide page based alloc/free helpers
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On 05/11/2018 12:19, Christoph Hellwig wrote:
> Some architectures support remapping highmem into DMA coherent
> allocations. To use the common code for them we need variants of
> dma_direct_{alloc,free}_pages that do not use kernel virtual addresses.

FWIW it's as much about non-cacheable remapping of lowmem as it is about
highmem. Regardless, the diff looks OK to me.

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

> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> include/linux/dma-direct.h | 3 +++
> kernel/dma/direct.c | 32 ++++++++++++++++++++++----------
> 2 files changed, 25 insertions(+), 10 deletions(-)
>
> diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
> index bd73e7a91410..5a7a3bbb912f 100644
> --- a/include/linux/dma-direct.h
> +++ b/include/linux/dma-direct.h
> @@ -67,6 +67,9 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
> dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs);
> void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr,
> dma_addr_t dma_addr, unsigned long attrs);
> +struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
> + dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs);
> +void __dma_direct_free_pages(struct device *dev, size_t size, struct page *page);
> dma_addr_t dma_direct_map_page(struct device *dev, struct page *page,
> unsigned long offset, size_t size, enum dma_data_direction dir,
> unsigned long attrs);
> diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
> index 22a12ab5a5e9..680287779b0a 100644
> --- a/kernel/dma/direct.c
> +++ b/kernel/dma/direct.c
> @@ -103,14 +103,13 @@ static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
> min_not_zero(dev->coherent_dma_mask, dev->bus_dma_mask);
> }
>
> -void *dma_direct_alloc_pages(struct device *dev, size_t size,
> +struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
> dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
> {
> unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
> int page_order = get_order(size);
> struct page *page = NULL;
> u64 phys_mask;
> - void *ret;
>
> if (attrs & DMA_ATTR_NO_WARN)
> gfp |= __GFP_NOWARN;
> @@ -150,11 +149,22 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
> }
> }
>
> + return page;
> +}
> +
> +void *dma_direct_alloc_pages(struct device *dev, size_t size,
> + dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
> +{
> + struct page *page;
> + void *ret;
> +
> + page = __dma_direct_alloc_pages(dev, size, dma_handle, gfp, attrs);
> if (!page)
> return NULL;
> +
> ret = page_address(page);
> if (force_dma_unencrypted()) {
> - set_memory_decrypted((unsigned long)ret, 1 << page_order);
> + set_memory_decrypted((unsigned long)ret, 1 << get_order(size));
> *dma_handle = __phys_to_dma(dev, page_to_phys(page));
> } else {
> *dma_handle = phys_to_dma(dev, page_to_phys(page));
> @@ -163,20 +173,22 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
> return ret;
> }
>
> -/*
> - * NOTE: this function must never look at the dma_addr argument, because we want
> - * to be able to use it as a helper for iommu implementations as well.
> - */
> +void __dma_direct_free_pages(struct device *dev, size_t size, struct page *page)
> +{
> + unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
> +
> + if (!dma_release_from_contiguous(dev, page, count))
> + __free_pages(page, get_order(size));
> +}
> +
> void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr,
> dma_addr_t dma_addr, unsigned long attrs)
> {
> - unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
> unsigned int page_order = get_order(size);
>
> if (force_dma_unencrypted())
> set_memory_encrypted((unsigned long)cpu_addr, 1 << page_order);
> - if (!dma_release_from_contiguous(dev, virt_to_page(cpu_addr), count))
> - free_pages((unsigned long)cpu_addr, page_order);
> + __dma_direct_free_pages(dev, size, virt_to_page(cpu_addr));
> }
>
> void *dma_direct_alloc(struct device *dev, size_t size,
>

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