Re: [PATCH 6/9] nouveau: simplify nouveau_dmem_migrate_to_ram

On 8/8/19 8:33 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@lst.de

Reviewed-by: Ralph Campbell rcampbell@nvidia.com

---

drivers/gpu/drm/nouveau/nouveau_dmem.c | 159 +++++++------------------ 1 file changed, 40 insertions(+), 119 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c index 21052a4aaf69..473195762974 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 +139,57 @@ 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_fault *vmf, struct migrate_vma *args,
  

• 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;

• struct page *dpage, *spage;
• vm_fault_t ret = VM_FAULT_SIGBUS;

You can remove this line and return VM_FAULT_SIGBUS in the error path below.

• /* 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;
  

• 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(args->src[0]);
• if (!spage || !(args->src[0] & 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, vmf->vma, vmf->address);
• 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;
  

• }
  

• *dma_addr = dma_map_page(dev, dpage, 0, PAGE_SIZE, DMA_BIDIRECTIONAL);
• if (dma_mapping_error(dev, *dma_addr))

• goto error_free_page;
  
  

• 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;
  

• }
  

• }

• 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;
  
  

• nouveau_fence_new(drm->dmem->migrate.chan, false, &fault->fence);
• return;

• args->dst[0] = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
• ret = 0;

This needs to be "return 0;" here so that dpage is not unmapped while the DMA I/O is in progress. It gets unmapped after the call to nouveau_dmem_fence_done() in nouveau_dmem_migrate_to_ram().

+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 ret;

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 +201,17 @@ 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, &args, &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 = {