From: Catalin Marinas <catalin.marinas@arm.com> To: Christoph Hellwig <hch@lst.de> Cc: Will Deacon <will.deacon@arm.com>, Robin Murphy <robin.murphy@arm.com>, x86@kernel.org, Tom Lendacky <thomas.lendacky@amd.com>, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>, linux-kernel@vger.kernel.org, Muli Ben-Yehuda <mulix@mulix.org>, iommu@lists.linux-foundation.org, David Woodhouse <dwmw2@infradead.org> Subject: Re: [PATCH 12/14] dma-direct: handle the memory encryption bit in common code Date: Mon, 19 Mar 2018 18:01:41 +0000 [thread overview] Message-ID: <20180319180141.w5o6lhknhd6q7ktq@armageddon.cambridge.arm.com> (raw) In-Reply-To: <20180319160343.GA29002@lst.de> On Mon, Mar 19, 2018 at 05:03:43PM +0100, Christoph Hellwig wrote: > On Mon, Mar 19, 2018 at 03:48:33PM +0000, Will Deacon wrote: > > Why can't we just resolve the conflict by adding the underscores? > > We can solve the conflict easily that way. But that's not the point. > > The point is that I've been fighting hard to consolidate dma code > given that the behavior really is common and not arch specific. And > this one is another case like that: the fact that the non-coherent > dma boundary is bigger than the exposed size is something that can > easily happen elsewhere, so there is no need to duplicate a lot > of code for that. I don't particularly like maintaining an arm64-specific dma-direct.h either but arm64 seems to be the only architecture that needs to potentially force a bounce when cache_line_size() > ARCH_DMA_MINALIGN and the device is non-coherent. Note that lib/swiotlb.c doesn't even deal with non-coherent DMA (e.g. map_sg doesn't have arch callbacks for cache maintenance), so not disrupting lib/swiotlb.c seems to be the least intrusive option. > Nevermind that the commit should at least be three different patches: > > (1) revert the broken original commit > (2) increase the dma min alignment Reverting the original commit could, on its own, break an SoC which expects ARCH_DMA_MINALIGN == 128. So these two should be a single commit (my patch only reverts the L1_CACHE_BYTES change rather than ARCH_DMA_MINALIGN, the latter being correct as 128). Anyway, it's queued already and we try not to rebase the branches we published. Fix-ups on top are fine though. > (3) put the swiotlb workaround in place As I said above, adding a check in swiotlb.c for !is_device_dma_coherent(dev) && (ARCH_DMA_MINALIGN < cache_line_size()) feels too architecture specific. Adding yet another hook like arch_dma_capable() doesn't feel right either since we already have the possibility to override dma_capable() by selecting ARCH_HAS_PHYS_TO_DMA. The "cleanest" I came up with for swiotlb.c was a new DMA_ATTR_FORCE_BOUNCE attribute. However, it required more changes to the arm64 dma-mapping.c than simply implementing an arch-specific dma_capable(). -- Catalin
WARNING: multiple messages have this Message-ID (diff)
From: Catalin Marinas <catalin.marinas-5wv7dgnIgG8@public.gmane.org> To: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org> Cc: Tom Lendacky <thomas.lendacky-5C7GfCeVMHo@public.gmane.org>, Konrad Rzeszutek Wilk <konrad.wilk-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>, David Woodhouse <dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>, x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Muli Ben-Yehuda <mulix-BzGcCpaT2IbYtjvyW6yDsg@public.gmane.org>, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Subject: Re: [PATCH 12/14] dma-direct: handle the memory encryption bit in common code Date: Mon, 19 Mar 2018 18:01:41 +0000 [thread overview] Message-ID: <20180319180141.w5o6lhknhd6q7ktq@armageddon.cambridge.arm.com> (raw) In-Reply-To: <20180319160343.GA29002-jcswGhMUV9g@public.gmane.org> On Mon, Mar 19, 2018 at 05:03:43PM +0100, Christoph Hellwig wrote: > On Mon, Mar 19, 2018 at 03:48:33PM +0000, Will Deacon wrote: > > Why can't we just resolve the conflict by adding the underscores? > > We can solve the conflict easily that way. But that's not the point. > > The point is that I've been fighting hard to consolidate dma code > given that the behavior really is common and not arch specific. And > this one is another case like that: the fact that the non-coherent > dma boundary is bigger than the exposed size is something that can > easily happen elsewhere, so there is no need to duplicate a lot > of code for that. I don't particularly like maintaining an arm64-specific dma-direct.h either but arm64 seems to be the only architecture that needs to potentially force a bounce when cache_line_size() > ARCH_DMA_MINALIGN and the device is non-coherent. Note that lib/swiotlb.c doesn't even deal with non-coherent DMA (e.g. map_sg doesn't have arch callbacks for cache maintenance), so not disrupting lib/swiotlb.c seems to be the least intrusive option. > Nevermind that the commit should at least be three different patches: > > (1) revert the broken original commit > (2) increase the dma min alignment Reverting the original commit could, on its own, break an SoC which expects ARCH_DMA_MINALIGN == 128. So these two should be a single commit (my patch only reverts the L1_CACHE_BYTES change rather than ARCH_DMA_MINALIGN, the latter being correct as 128). Anyway, it's queued already and we try not to rebase the branches we published. Fix-ups on top are fine though. > (3) put the swiotlb workaround in place As I said above, adding a check in swiotlb.c for !is_device_dma_coherent(dev) && (ARCH_DMA_MINALIGN < cache_line_size()) feels too architecture specific. Adding yet another hook like arch_dma_capable() doesn't feel right either since we already have the possibility to override dma_capable() by selecting ARCH_HAS_PHYS_TO_DMA. The "cleanest" I came up with for swiotlb.c was a new DMA_ATTR_FORCE_BOUNCE attribute. However, it required more changes to the arm64 dma-mapping.c than simply implementing an arch-specific dma_capable(). -- Catalin
next prev parent reply other threads:[~2018-03-19 18:02 UTC|newest] Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-03-19 10:38 use generic dma-direct and swiotlb code for x86 V3 Christoph Hellwig 2018-03-19 10:38 ` Christoph Hellwig 2018-03-19 10:38 ` [PATCH 01/14] x86: remove X86_PPRO_FENCE Christoph Hellwig 2018-03-19 10:38 ` Christoph Hellwig 2018-03-20 11:04 ` [tip:x86/pti] x86/cpu: Remove the CONFIG_X86_PPRO_FENCE=y quirk tip-bot for Christoph Hellwig 2018-03-20 12:51 ` Peter Zijlstra 2018-03-19 10:38 ` [PATCH 02/14] x86: remove dma_alloc_coherent_mask Christoph Hellwig 2018-03-19 10:38 ` Christoph Hellwig 2018-03-23 19:48 ` [tip:x86/dma] x86/dma: Remove dma_alloc_coherent_mask() tip-bot for Christoph Hellwig 2018-03-19 10:38 ` [PATCH 03/14] x86: use dma-direct Christoph Hellwig 2018-03-19 10:38 ` Christoph Hellwig 2018-03-23 19:49 ` [tip:x86/dma] x86/dma: Use DMA-direct (CONFIG_DMA_DIRECT_OPS=y) tip-bot for Christoph Hellwig 2018-03-19 10:38 ` [PATCH 04/14] x86: use generic swiotlb_ops Christoph Hellwig 2018-03-19 10:38 ` Christoph Hellwig 2018-03-23 19:49 ` [tip:x86/dma] x86/dma: Use " tip-bot for Christoph Hellwig 2018-03-19 10:38 ` [PATCH 05/14] x86/amd_gart: look at coherent_dma_mask instead of GFP_DMA Christoph Hellwig 2018-03-19 10:38 ` Christoph Hellwig 2018-03-23 19:50 ` [tip:x86/dma] x86/dma/amd_gart: Look at dev->coherent_dma_mask " tip-bot for Christoph Hellwig 2018-03-19 10:38 ` [PATCH 06/14] x86/amd_gart: use dma_direct_{alloc,free} Christoph Hellwig 2018-03-19 10:38 ` Christoph Hellwig 2018-03-23 19:50 ` [tip:x86/dma] x86/dma/amd_gart: Use dma_direct_{alloc,free}() tip-bot for Christoph Hellwig 2018-03-19 10:38 ` [PATCH 07/14] iommu/amd_iommu: use dma_direct_{alloc,free} Christoph Hellwig 2018-03-19 10:38 ` Christoph Hellwig 2018-03-23 19:51 ` [tip:x86/dma] iommu/amd_iommu: Use CONFIG_DMA_DIRECT_OPS=y and dma_direct_{alloc,free}() tip-bot for Christoph Hellwig 2018-03-19 10:38 ` [PATCH 08/14] iommu/intel-iommu: cleanup intel_{alloc,free}_coherent Christoph Hellwig 2018-03-19 10:38 ` Christoph Hellwig 2018-03-23 19:51 ` [tip:x86/dma] iommu/intel-iommu: Enable CONFIG_DMA_DIRECT_OPS=y and clean up intel_{alloc,free}_coherent() tip-bot for Christoph Hellwig 2018-03-19 10:38 ` [PATCH 09/14] x86: remove dma_alloc_coherent_gfp_flags Christoph Hellwig 2018-03-19 10:38 ` Christoph Hellwig 2018-03-23 19:52 ` [tip:x86/dma] x86/dma: Remove dma_alloc_coherent_gfp_flags() tip-bot for Christoph Hellwig 2018-03-19 10:38 ` [PATCH 10/14] set_memory.h: provide set_memory_{en,de}crypted stubs Christoph Hellwig 2018-03-19 10:38 ` Christoph Hellwig 2018-03-19 14:21 ` Tom Lendacky 2018-03-19 14:21 ` Tom Lendacky 2018-03-23 19:52 ` [tip:x86/dma] set_memory.h: Provide set_memory_{en,de}crypted() stubs tip-bot for Christoph Hellwig 2018-03-19 10:38 ` [PATCH 11/14] swiotlb: remove swiotlb_set_mem_attributes Christoph Hellwig 2018-03-19 10:38 ` Christoph Hellwig 2018-03-19 14:41 ` Tom Lendacky 2018-03-19 14:41 ` Tom Lendacky 2018-03-23 19:52 ` [tip:x86/dma] dma/swiotlb: Remove swiotlb_set_mem_attributes() tip-bot for Christoph Hellwig 2018-03-19 10:38 ` [PATCH 12/14] dma-direct: handle the memory encryption bit in common code Christoph Hellwig 2018-03-19 10:38 ` Christoph Hellwig 2018-03-19 14:50 ` Tom Lendacky 2018-03-19 14:50 ` Tom Lendacky 2018-03-19 15:19 ` Robin Murphy 2018-03-19 15:19 ` Robin Murphy 2018-03-19 15:24 ` Christoph Hellwig 2018-03-19 15:24 ` Christoph Hellwig 2018-03-19 15:37 ` Robin Murphy 2018-03-19 15:37 ` Robin Murphy 2018-03-19 15:48 ` Will Deacon 2018-03-19 15:48 ` Will Deacon 2018-03-19 16:03 ` Christoph Hellwig 2018-03-19 16:03 ` Christoph Hellwig 2018-03-19 16:55 ` Will Deacon 2018-03-19 16:55 ` Will Deacon 2018-03-19 18:01 ` Catalin Marinas [this message] 2018-03-19 18:01 ` Catalin Marinas 2018-03-19 19:49 ` Christoph Hellwig 2018-03-19 19:49 ` Christoph Hellwig 2018-03-20 16:23 ` Catalin Marinas 2018-03-20 16:23 ` Catalin Marinas 2018-03-23 19:53 ` [tip:x86/dma] dma/direct: Handle " tip-bot for Christoph Hellwig 2018-03-19 10:38 ` [PATCH 13/14] dma-direct: handle force decryption for dma coherent buffers " Christoph Hellwig 2018-03-19 10:38 ` Christoph Hellwig 2018-03-19 14:51 ` Tom Lendacky 2018-03-19 14:51 ` Tom Lendacky 2018-03-23 19:53 ` [tip:x86/dma] dma/direct: Handle force decryption for DMA " tip-bot for Christoph Hellwig 2018-03-19 10:38 ` [PATCH 14/14] swiotlb: remove swiotlb_{alloc,free}_coherent Christoph Hellwig 2018-03-19 10:38 ` Christoph Hellwig 2018-03-23 19:54 ` [tip:x86/dma] dma/swiotlb: Remove swiotlb_{alloc,free}_coherent() tip-bot for Christoph Hellwig 2018-03-19 14:00 ` use generic dma-direct and swiotlb code for x86 V3 Tom Lendacky 2018-03-19 14:00 ` Tom Lendacky 2018-03-19 14:56 ` Thomas Gleixner 2018-03-19 14:56 ` Thomas Gleixner 2018-03-19 15:27 ` Konrad Rzeszutek Wilk 2018-03-19 15:27 ` Konrad Rzeszutek Wilk 2018-03-19 15:28 ` Christoph Hellwig 2018-03-20 8:37 ` Ingo Molnar 2018-03-20 8:37 ` Ingo Molnar 2018-03-20 8:44 ` Christoph Hellwig 2018-03-20 8:44 ` Christoph Hellwig 2018-03-20 9:03 ` Ingo Molnar 2018-03-20 9:03 ` Ingo Molnar [not found] ` <20180320090351.2qnwcsauhodrqxdj-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> 2018-03-20 11:25 ` Konrad Rzeszutek Wilk 2018-03-20 15:16 ` Christoph Hellwig 2018-03-20 15:16 ` Christoph Hellwig 2018-03-21 14:32 ` Konrad Rzeszutek Wilk 2018-03-21 14:32 ` Konrad Rzeszutek Wilk -- strict thread matches above, loose matches on Subject: below -- 2018-03-14 17:51 use generic dma-direct and swiotlb code for x86 V2 Christoph Hellwig 2018-03-14 17:52 ` [PATCH 12/14] dma-direct: handle the memory encryption bit in common code Christoph Hellwig 2018-03-14 17:52 ` Christoph Hellwig
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