On Thu, Jul 16, 2015 at 07:40:14PM +0100, Robin Murphy wrote:
> +static void *__iommu_alloc_attrs(struct device *dev, size_t size,
> + dma_addr_t *handle, gfp_t gfp,
> + struct dma_attrs *attrs)
> +{
> + bool coherent = is_device_dma_coherent(dev);
> + int ioprot = dma_direction_to_prot(DMA_BIDIRECTIONAL, coherent);
> + void *addr;
> +
> + if (WARN(!dev, "cannot create IOMMU mapping for unknown device\n"))
> + return NULL;
> +
> + /*
> + * Some drivers rely on this, and we may not want to potentially
> + * expose stale kernel data to devices anyway.
> + */
> + gfp |= __GFP_ZERO;
> +
> + if (gfp & __GFP_WAIT) {
> + struct page **pages;
> + pgprot_t pgprot = coherent ? __pgprot(PROT_NORMAL) :
> + __pgprot(PROT_NORMAL_NC);
> +
> + pgprot = __get_dma_pgprot(attrs, pgprot, coherent);
I think you can simplify this:
pgprot_t pgprot = __get_dma_pgprot(attrs, PAGE_KERNEL,
coherent);
(and we could do the same in __dma_alloc)
> + pages = iommu_dma_alloc(dev, size, gfp, ioprot, handle,
> + coherent ? NULL : flush_page);
I commented on patch 2/4. If we checked for IOMMU_CACHE in
iommu_dma_alloc(), we could always pass flush_page here without the
NULL.
> + if (!pages)
> + return NULL;
> +
> + addr = dma_common_pages_remap(pages, size, VM_USERMAP, pgprot,
> + __builtin_return_address(0));
> + if (!addr)
> + iommu_dma_free(dev, pages, size, handle);
For arm64, it would have been easier to simply flush the caches here and
avoid the flush_page argument. However, I reread your earlier reply, so
if we ever honour the ATTR_NO_KERNEL_MAPPING, then we would have to
iterate over the individual pages in the arch code. Let's leave it as
per your patch 2/4 (with a flush_page argument).
--
Catalin
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