From mboxrd@z Thu Jan 1 00:00:00 1970 From: Robin Murphy Subject: Re: [PATCH 4/9] dma-mapping: move the arm64 ncoherent alloc/free support to common code Date: Fri, 30 Nov 2018 19:05:23 +0000 Message-ID: <5526bc61-57a3-54ff-60c6-e9963230af22@arm.com> References: <20181105121931.13481-1-hch@lst.de> <20181105121931.13481-5-hch@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20181105121931.13481-5-hch-jcswGhMUV9g@public.gmane.org> Content-Language: en-GB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Christoph Hellwig , iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Cc: Catalin Marinas , Will Deacon , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Guo Ren , Laura Abbott , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: iommu@lists.linux-foundation.org On 05/11/2018 12:19, Christoph Hellwig wrote: > The arm64 codebase to implement coherent dma allocation for architectures > with non-coherent DMA is a good start for a generic implementation, given > that is uses the generic remap helpers, provides the atomic pool for > allocations that can't sleep and still is realtively simple and well > tested. Move it to kernel/dma and allow architectures to opt into it > using a config symbol. Architectures just need to provide a new > arch_dma_prep_coherent helper to writeback an invalidate the caches > for any memory that gets remapped for uncached access. It's a bit yuck that we now end up with arch_* hooks being a mix of arch code and not-actually-arch-code, but I guess there's some hope of coming back and streamlining things in future once all the big moves are done. I can't really be bothered to nitpick the typos above and the slight inconsistencies in some of the cosmetic code changes, but one worthwhile thing stands out... > Signed-off-by: Christoph Hellwig > --- > arch/arm64/Kconfig | 2 +- > arch/arm64/mm/dma-mapping.c | 184 ++------------------------------ > include/linux/dma-mapping.h | 5 + > include/linux/dma-noncoherent.h | 2 + > kernel/dma/Kconfig | 6 ++ > kernel/dma/remap.c | 158 ++++++++++++++++++++++++++- > 6 files changed, 181 insertions(+), 176 deletions(-) [...] > +void *dma_alloc_from_pool(size_t size, struct page **ret_page, gfp_t flags) > +{ > + unsigned long val; > + void *ptr = NULL; > + > + if (!atomic_pool) { > + WARN(1, "coherent pool not initialised!\n"); > + return NULL; > + } > + > + val = gen_pool_alloc(atomic_pool, size); > + if (val) { > + phys_addr_t phys = gen_pool_virt_to_phys(atomic_pool, val); > + > + *ret_page = phys_to_page(phys); Looks like phys_to_page() isn't particularly portable, so we probably want an explicit pfn_to_page(__phys_to_pfn(phys)) here. Otherwise, the fundamental refactoring looks OK. Reviewed-by: Robin Murphy [ In fact, looking at phys_to_page(), microblaze, riscv, unicore and csky (by the end of this series if it's fixed here) don't need to define it at all; s390 defines it for the sake of a single call in a single driver; it's used in two other places in arm-related drivers but at least one of those is clearly wrong. All in all it's quite the sorry mess. ] > + ptr = (void *)val; > + memset(ptr, 0, size); > + } > + > + return ptr; > +} > + > +bool dma_free_from_pool(void *start, size_t size) > +{ > + if (!dma_in_atomic_pool(start, size)) > + return false; > + gen_pool_free(atomic_pool, (unsigned long)start, size); > + return true; > +} > + > +void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle, > + gfp_t flags, unsigned long attrs) > +{ > + struct page *page = NULL; > + void *ret, *kaddr; > + > + size = PAGE_ALIGN(size); > + > + if (!gfpflags_allow_blocking(flags)) { > + ret = dma_alloc_from_pool(size, &page, flags); > + if (!ret) > + return NULL; > + *dma_handle = phys_to_dma(dev, page_to_phys(page)); > + return ret; > + } > + > + kaddr = dma_direct_alloc_pages(dev, size, dma_handle, flags, attrs); > + if (!kaddr) > + return NULL; > + page = virt_to_page(kaddr); > + > + /* remove any dirty cache lines on the kernel alias */ > + arch_dma_prep_coherent(page, size); > + > + /* create a coherent mapping */ > + ret = dma_common_contiguous_remap(page, size, VM_USERMAP, > + arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs), > + __builtin_return_address(0)); > + if (!ret) > + dma_direct_free_pages(dev, size, kaddr, *dma_handle, attrs); > + return ret; > +} > + > +void arch_dma_free(struct device *dev, size_t size, void *vaddr, > + dma_addr_t dma_handle, unsigned long attrs) > +{ > + if (!dma_free_from_pool(vaddr, PAGE_ALIGN(size))) { > + void *kaddr = phys_to_virt(dma_to_phys(dev, dma_handle)); > + > + vunmap(vaddr); > + dma_direct_free_pages(dev, size, kaddr, dma_handle, attrs); > + } > +} > + > +long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr, > + dma_addr_t dma_addr) > +{ > + return __phys_to_pfn(dma_to_phys(dev, dma_addr)); > +} > +#endif /* CONFIG_DMA_DIRECT_REMAP */ >