Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755040AbYHQPsp (ORCPT ); Sun, 17 Aug 2008 11:48:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752633AbYHQPsf (ORCPT ); Sun, 17 Aug 2008 11:48:35 -0400 Received: from sh.osrg.net ([192.16.179.4]:56975 "EHLO sh.osrg.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752560AbYHQPse (ORCPT ); Sun, 17 Aug 2008 11:48:34 -0400 Date: Mon, 18 Aug 2008 00:48:05 +0900 To: mingo@elte.hu Cc: fujita.tomonori@lab.ntt.co.jp, prarit@redhat.com, jbarnes@virtuousgeek.org, joro@8bytes.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org Subject: Re: [PATCH]: PCI: GART iommu alignment fixes [v2] From: FUJITA Tomonori In-Reply-To: <20080817154213.GB6411@elte.hu> References: <20080817125614.GA31875@elte.hu> <20080818003648M.fujita.tomonori@lab.ntt.co.jp> <20080817154213.GB6411@elte.hu> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-Id: <20080818004844G.fujita.tomonori@lab.ntt.co.jp> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5710 Lines: 137 On Sun, 17 Aug 2008 17:42:13 +0200 Ingo Molnar wrote: > > * FUJITA Tomonori wrote: > > > The above commit log of Prarit's patch is completely wrong (so I wrote > > this patch). To avoid misunderstanding, can you apply this patch with > > a proper description like this: > > sure, i've created the commit below - is that fine? > > Ingo I think that 'v2' in the subject is unnecessary. The rest looks fine. Thanks, > ---------------> > From 3f18931be15856db01a216995670412e4421f3c9 Mon Sep 17 00:00:00 2001 > From: FUJITA Tomonori > Date: Mon, 18 Aug 2008 00:36:18 +0900 > Subject: [PATCH] x86 gart: allocate size-aligned address for alloc_coherent, v2 > > This patch changes GART IOMMU to return a size aligned address wrt > dma_alloc_coherent, as DMA-mapping.txt defines: > > The cpu return address and the DMA bus master address are both > guaranteed to be aligned to the smallest PAGE_SIZE order which > is greater than or equal to the requested size. This invariant > exists (for example) to guarantee that if you allocate a chunk > which is smaller than or equal to 64 kilobytes, the extent of the > buffer you receive will not cross a 64K boundary. > > But it is very unlikely that this matters. As DMA-mapping.txt > explains, This invariant is to avoid the boundary problem (such as > 64K). Now the majority of IOMMUs including GART (except for Intel > IOMMU) don't allocate a buffer that crosses a 64K boundary wrt all the > DMA mapping interfaces (dma_alloc_coherent, dma_map_sg, and > dma_map_single) because of segment_boundary_mask in struct > device_dma_parameters. > > Signed-off-by: FUJITA Tomonori > Signed-off-by: Ingo Molnar > --- > arch/x86/kernel/pci-gart_64.c | 25 ++++++++++++++++--------- > 1 files changed, 16 insertions(+), 9 deletions(-) > > diff --git a/arch/x86/kernel/pci-gart_64.c b/arch/x86/kernel/pci-gart_64.c > index cdab678..4d8efb0 100644 > --- a/arch/x86/kernel/pci-gart_64.c > +++ b/arch/x86/kernel/pci-gart_64.c > @@ -82,7 +82,8 @@ AGPEXTERN __u32 *agp_gatt_table; > static unsigned long next_bit; /* protected by iommu_bitmap_lock */ > static int need_flush; /* global flush state. set for each gart wrap */ > > -static unsigned long alloc_iommu(struct device *dev, int size) > +static unsigned long alloc_iommu(struct device *dev, int size, > + unsigned long align_mask) > { > unsigned long offset, flags; > unsigned long boundary_size; > @@ -95,11 +96,12 @@ static unsigned long alloc_iommu(struct device *dev, int size) > > spin_lock_irqsave(&iommu_bitmap_lock, flags); > offset = iommu_area_alloc(iommu_gart_bitmap, iommu_pages, next_bit, > - size, base_index, boundary_size, 0); > + size, base_index, boundary_size, align_mask); > if (offset == -1) { > need_flush = 1; > offset = iommu_area_alloc(iommu_gart_bitmap, iommu_pages, 0, > - size, base_index, boundary_size, 0); > + size, base_index, boundary_size, > + align_mask); > } > if (offset != -1) { > next_bit = offset+size; > @@ -236,10 +238,10 @@ nonforced_iommu(struct device *dev, unsigned long addr, size_t size) > * Caller needs to check if the iommu is needed and flush. > */ > static dma_addr_t dma_map_area(struct device *dev, dma_addr_t phys_mem, > - size_t size, int dir) > + size_t size, int dir, unsigned long align_mask) > { > unsigned long npages = iommu_num_pages(phys_mem, size); > - unsigned long iommu_page = alloc_iommu(dev, npages); > + unsigned long iommu_page = alloc_iommu(dev, npages, align_mask); > int i; > > if (iommu_page == -1) { > @@ -262,7 +264,11 @@ static dma_addr_t dma_map_area(struct device *dev, dma_addr_t phys_mem, > static dma_addr_t > gart_map_simple(struct device *dev, phys_addr_t paddr, size_t size, int dir) > { > - dma_addr_t map = dma_map_area(dev, paddr, size, dir); > + dma_addr_t map; > + unsigned long align_mask; > + > + align_mask = (1UL << get_order(size)) - 1; > + map = dma_map_area(dev, paddr, size, dir, align_mask); > > flush_gart(); > > @@ -281,7 +287,8 @@ gart_map_single(struct device *dev, phys_addr_t paddr, size_t size, int dir) > if (!need_iommu(dev, paddr, size)) > return paddr; > > - bus = gart_map_simple(dev, paddr, size, dir); > + bus = dma_map_area(dev, paddr, size, dir, 0); > + flush_gart(); > > return bus; > } > @@ -340,7 +347,7 @@ static int dma_map_sg_nonforce(struct device *dev, struct scatterlist *sg, > unsigned long addr = sg_phys(s); > > if (nonforced_iommu(dev, addr, s->length)) { > - addr = dma_map_area(dev, addr, s->length, dir); > + addr = dma_map_area(dev, addr, s->length, dir, 0); > if (addr == bad_dma_address) { > if (i > 0) > gart_unmap_sg(dev, sg, i, dir); > @@ -362,7 +369,7 @@ static int __dma_map_cont(struct device *dev, struct scatterlist *start, > int nelems, struct scatterlist *sout, > unsigned long pages) > { > - unsigned long iommu_start = alloc_iommu(dev, pages); > + unsigned long iommu_start = alloc_iommu(dev, pages, 0); > unsigned long iommu_page = iommu_start; > struct scatterlist *s; > int i; > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/