From: Christoph Hellwig <hch@lst.de>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Joerg Roedel <joro@8bytes.org>, Will Deacon <will.deacon@arm.com>,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
Christoph Hellwig <hch@lst.de>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 03/19] dma-iommu: don't use a scatterlist in iommu_dma_alloc
Date: Mon, 11 Feb 2019 17:00:49 +0100 [thread overview]
Message-ID: <20190211160049.GB27745@lst.de> (raw)
In-Reply-To: <f59852aa-394c-3165-f7c0-fa6cdcea059f@arm.com>
On Wed, Feb 06, 2019 at 03:28:28PM +0000, Robin Murphy wrote:
> Because if iommu_map() only gets called at PAGE_SIZE granularity, then the
> IOMMU PTEs will be created at PAGE_SIZE (or smaller) granularity, so any
> effort to get higher-order allocations matching larger IOMMU block sizes is
> wasted, and we may as well have just done this:
>
> for (i = 0; i < count; i++) {
> struct page *page = alloc_page(gfp);
> ...
> iommu_map(..., page_to_phys(page), PAGE_SIZE, ...);
> }
True. I've dropped this patch.
> Really, it's a shame we have to split huge pages for the CPU remap, since
> in the common case the CPU MMU will have a matching block size, but IIRC
> there was something in vmap() or thereabouts that explicitly chokes on
> them.
That just needs a volunteer to fix the implementation, as there is no
fundamental reason not to remap large pages.
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next prev parent reply other threads:[~2019-02-11 16:01 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-14 9:41 implement generic dma_map_ops for IOMMUs Christoph Hellwig
2019-01-14 9:41 ` [PATCH 01/19] dma-mapping: add a Kconfig symbol to indicated arch_dma_prep_coherent presence Christoph Hellwig
2019-02-01 14:22 ` Robin Murphy
2019-02-01 16:12 ` Christoph Hellwig
2019-01-14 9:41 ` [PATCH 02/19] dma-iommu: cleanup dma-iommu.h Christoph Hellwig
2019-02-01 14:47 ` Robin Murphy
2019-02-01 16:13 ` Christoph Hellwig
2019-02-06 15:08 ` Robin Murphy
2019-02-11 15:59 ` Christoph Hellwig
2019-01-14 9:41 ` [PATCH 03/19] dma-iommu: don't use a scatterlist in iommu_dma_alloc Christoph Hellwig
2019-02-01 15:24 ` Robin Murphy
2019-02-01 16:16 ` Christoph Hellwig
2019-02-06 15:28 ` Robin Murphy
2019-02-11 16:00 ` Christoph Hellwig [this message]
2019-01-14 9:41 ` [PATCH 04/19] dma-iommu: remove the flush_page callback Christoph Hellwig
2019-02-01 15:28 ` Robin Murphy
2019-01-14 9:41 ` [PATCH 05/19] dma-iommu: move the arm64 wrappers to common code Christoph Hellwig
2019-01-14 9:41 ` [PATCH 06/19] dma-iommu: fix and refactor iommu_dma_mmap Christoph Hellwig
2019-02-05 15:02 ` Robin Murphy
2019-02-11 16:03 ` Christoph Hellwig
2019-01-14 9:41 ` [PATCH 07/19] dma-iommu: fix and refactor iommu_dma_get_sgtable Christoph Hellwig
2019-01-14 9:41 ` [PATCH 08/19] dma-iommu: move __iommu_dma_map Christoph Hellwig
2019-01-14 9:41 ` [PATCH 09/19] dma-iommu: refactor page array remap helpers Christoph Hellwig
2019-01-14 9:41 ` [PATCH 10/19] dma-iommu: factor atomic pool allocations into helpers Christoph Hellwig
2019-01-14 9:41 ` [PATCH 11/19] dma-iommu: factor contiguous " Christoph Hellwig
2019-01-14 9:41 ` [PATCH 12/19] dma-iommu: refactor iommu_dma_free Christoph Hellwig
2019-01-14 9:41 ` [PATCH 13/19] dma-iommu: don't remap contiguous allocations for coherent devices Christoph Hellwig
2019-01-14 9:41 ` [PATCH 14/19] dma-iommu: factor contiguous remapped allocations into helpers Christoph Hellwig
2019-01-14 9:41 ` [PATCH 15/19] dma-iommu: refactor iommu_dma_alloc Christoph Hellwig
2019-01-14 9:41 ` [PATCH 16/19] dma-iommu: don't depend on CONFIG_DMA_DIRECT_REMAP Christoph Hellwig
2019-02-06 11:55 ` Robin Murphy
2019-02-11 16:39 ` Christoph Hellwig
2019-01-14 9:41 ` [PATCH 17/19] dma-iommu: switch copyright boilerplace to SPDX Christoph Hellwig
2019-02-06 11:57 ` Robin Murphy
2019-01-14 9:41 ` [PATCH 18/19] arm64: switch copyright boilerplace to SPDX in dma-mapping.c Christoph Hellwig
2019-02-06 12:19 ` Robin Murphy
2019-01-14 9:41 ` [PATCH 19/19] arm64: trim includes " Christoph Hellwig
2019-01-28 7:53 ` implement generic dma_map_ops for IOMMUs Christoph Hellwig
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