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Message-ID: <0c07ed9b-96c3-ec06-c6c5-1676f5c91eda@nvidia.com>
Date: Mon, 29 Jul 2019 16:26:22 -0700
From: Ralph Campbell <rcampbell@...dia.com>
To: Christoph Hellwig <hch@....de>,
Jérôme Glisse <jglisse@...hat.com>,
Jason Gunthorpe <jgg@...lanox.com>,
Ben Skeggs <bskeggs@...hat.com>
CC: Bharata B Rao <bharata@...ux.ibm.com>,
Andrew Morton <akpm@...ux-foundation.org>,
<linux-mm@...ck.org>, <nouveau@...ts.freedesktop.org>,
<dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 5/9] nouveau: simplify nouveau_dmem_migrate_to_ram
On 7/29/19 7:28 AM, Christoph Hellwig wrote:
> Factor the main copy page to ram routine out into a helper that acts on
> a single page and which doesn't require the nouveau_dmem_fault
> structure for argument passing. Also remove the loop over multiple
> pages as we only handle one at the moment, although the structure of
> the main worker function makes it relatively easy to add multi page
> support back if needed in the future. But at least for now this avoid
> the needed to dynamically allocate memory for the dma addresses in
> what is essentially the page fault path.
>
> Signed-off-by: Christoph Hellwig <hch@....de>
Reviewed-by: Ralph Campbell <rcampbell@...dia.com>
> ---
> drivers/gpu/drm/nouveau/nouveau_dmem.c | 158 ++++++-------------------
> 1 file changed, 39 insertions(+), 119 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c
> index 21052a4aaf69..036e6c07d489 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
> @@ -86,13 +86,6 @@ static inline struct nouveau_dmem *page_to_dmem(struct page *page)
> return container_of(page->pgmap, struct nouveau_dmem, pagemap);
> }
>
> -struct nouveau_dmem_fault {
> - struct nouveau_drm *drm;
> - struct nouveau_fence *fence;
> - dma_addr_t *dma;
> - unsigned long npages;
> -};
> -
> struct nouveau_migrate {
> struct vm_area_struct *vma;
> struct nouveau_drm *drm;
> @@ -146,130 +139,55 @@ static void nouveau_dmem_fence_done(struct nouveau_fence **fence)
> }
> }
>
> -static void
> -nouveau_dmem_fault_alloc_and_copy(struct vm_area_struct *vma,
> - const unsigned long *src_pfns,
> - unsigned long *dst_pfns,
> - unsigned long start,
> - unsigned long end,
> - struct nouveau_dmem_fault *fault)
> +static vm_fault_t nouveau_dmem_fault_copy_one(struct nouveau_drm *drm,
> + struct vm_area_struct *vma, unsigned long addr,
> + unsigned long src, unsigned long *dst, dma_addr_t *dma_addr)
> {
> - struct nouveau_drm *drm = fault->drm;
> struct device *dev = drm->dev->dev;
> - unsigned long addr, i, npages = 0;
> - nouveau_migrate_copy_t copy;
> - int ret;
> -
> -
> - /* First allocate new memory */
> - for (addr = start, i = 0; addr < end; addr += PAGE_SIZE, i++) {
> - struct page *dpage, *spage;
> -
> - dst_pfns[i] = 0;
> - spage = migrate_pfn_to_page(src_pfns[i]);
> - if (!spage || !(src_pfns[i] & MIGRATE_PFN_MIGRATE))
> - continue;
> + struct page *dpage, *spage;
>
> - dpage = alloc_page_vma(GFP_HIGHUSER, vma, addr);
> - if (!dpage) {
> - dst_pfns[i] = MIGRATE_PFN_ERROR;
> - continue;
> - }
> - lock_page(dpage);
> -
> - dst_pfns[i] = migrate_pfn(page_to_pfn(dpage)) |
> - MIGRATE_PFN_LOCKED;
> - npages++;
> - }
> + spage = migrate_pfn_to_page(src);
> + if (!spage || !(src & MIGRATE_PFN_MIGRATE))
> + return 0;
>
> - /* Allocate storage for DMA addresses, so we can unmap later. */
> - fault->dma = kmalloc(sizeof(*fault->dma) * npages, GFP_KERNEL);
> - if (!fault->dma)
> + dpage = alloc_page_vma(GFP_HIGHUSER, args->vma, addr);
> + if (!dpage)
> goto error;
> + lock_page(dpage);
>
> - /* Copy things over */
> - copy = drm->dmem->migrate.copy_func;
> - for (addr = start, i = 0; addr < end; addr += PAGE_SIZE, i++) {
> - struct page *spage, *dpage;
> -
> - dpage = migrate_pfn_to_page(dst_pfns[i]);
> - if (!dpage || dst_pfns[i] == MIGRATE_PFN_ERROR)
> - continue;
> -
> - spage = migrate_pfn_to_page(src_pfns[i]);
> - if (!spage || !(src_pfns[i] & MIGRATE_PFN_MIGRATE)) {
> - dst_pfns[i] = MIGRATE_PFN_ERROR;
> - __free_page(dpage);
> - continue;
> - }
> -
> - fault->dma[fault->npages] =
> - dma_map_page_attrs(dev, dpage, 0, PAGE_SIZE,
> - PCI_DMA_BIDIRECTIONAL,
> - DMA_ATTR_SKIP_CPU_SYNC);
> - if (dma_mapping_error(dev, fault->dma[fault->npages])) {
> - dst_pfns[i] = MIGRATE_PFN_ERROR;
> - __free_page(dpage);
> - continue;
> - }
> -
> - ret = copy(drm, 1, NOUVEAU_APER_HOST,
> - fault->dma[fault->npages++],
> - NOUVEAU_APER_VRAM,
> - nouveau_dmem_page_addr(spage));
> - if (ret) {
> - dst_pfns[i] = MIGRATE_PFN_ERROR;
> - __free_page(dpage);
> - continue;
> - }
> - }
> + *dma_addr = dma_map_page(dev, dpage, 0, PAGE_SIZE, DMA_BIDIRECTIONAL);
> + if (dma_mapping_error(dev, *dma_addr))
> + goto error_free_page;
>
> - nouveau_fence_new(drm->dmem->migrate.chan, false, &fault->fence);
> + if (drm->dmem->migrate.copy_func(drm, 1, NOUVEAU_APER_HOST, *dma_addr,
> + NOUVEAU_APER_VRAM, nouveau_dmem_page_addr(spage)))
> + goto error_dma_unmap;
>
> - return;
> + *dst = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
Need a "return 0;" here or you undo the work done.
>
> +error_dma_unmap:
> + dma_unmap_page(dev, *dma_addr, PAGE_SIZE, DMA_BIDIRECTIONAL);
> +error_free_page:
> + __free_page(dpage);
> error:
> - for (addr = start, i = 0; addr < end; addr += PAGE_SIZE, ++i) {
> - struct page *page;
> -
> - if (!dst_pfns[i] || dst_pfns[i] == MIGRATE_PFN_ERROR)
> - continue;
> -
> - page = migrate_pfn_to_page(dst_pfns[i]);
> - dst_pfns[i] = MIGRATE_PFN_ERROR;
> - if (page == NULL)
> - continue;
> -
> - __free_page(page);
> - }
> -}
> -
> -static void
> -nouveau_dmem_fault_finalize_and_map(struct nouveau_dmem_fault *fault)
> -{
> - struct nouveau_drm *drm = fault->drm;
> -
> - nouveau_dmem_fence_done(&fault->fence);
> -
> - while (fault->npages--) {
> - dma_unmap_page(drm->dev->dev, fault->dma[fault->npages],
> - PAGE_SIZE, PCI_DMA_BIDIRECTIONAL);
> - }
> - kfree(fault->dma);
> + return VM_FAULT_SIGBUS;
> }
>
> static vm_fault_t nouveau_dmem_migrate_to_ram(struct vm_fault *vmf)
> {
> struct nouveau_dmem *dmem = page_to_dmem(vmf->page);
> - unsigned long src[1] = {0}, dst[1] = {0};
> + struct nouveau_drm *drm = dmem->drm;
> + struct nouveau_fence *fence;
> + unsigned long src = 0, dst = 0;
> + dma_addr_t dma_addr = 0;
> + vm_fault_t ret;
> struct migrate_vma args = {
> .vma = vmf->vma,
> .start = vmf->address,
> .end = vmf->address + PAGE_SIZE,
> - .src = src,
> - .dst = dst,
> + .src = &src,
> + .dst = &dst,
> };
> - struct nouveau_dmem_fault fault = { .drm = dmem->drm };
>
> /*
> * FIXME what we really want is to find some heuristic to migrate more
> @@ -281,16 +199,18 @@ static vm_fault_t nouveau_dmem_migrate_to_ram(struct vm_fault *vmf)
> if (!args.cpages)
> return 0;
>
> - nouveau_dmem_fault_alloc_and_copy(args.vma, src, dst, args.start,
> - args.end, &fault);
> - migrate_vma_pages(&args);
> - nouveau_dmem_fault_finalize_and_map(&fault);
> + ret = nouveau_dmem_fault_copy_one(drm, vmf->vma, vmf->address, src,
> + &dst, &dma_addr);
> + if (ret || dst == 0)
> + goto done;
>
> + nouveau_fence_new(dmem->migrate.chan, false, &fence);
> + migrate_vma_pages(&args);
> + nouveau_dmem_fence_done(&fence);
> + dma_unmap_page(drm->dev->dev, dma_addr, PAGE_SIZE, DMA_BIDIRECTIONAL);
> +done:
> migrate_vma_finalize(&args);
> - if (dst[0] == MIGRATE_PFN_ERROR)
> - return VM_FAULT_SIGBUS;
> -
> - return 0;
> + return ret;
> }
>
> static const struct dev_pagemap_ops nouveau_dmem_pagemap_ops = {
>
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