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> >  } > >   > > +/** > > + * struct drm_pagemap_iova_state - DRM pagemap IOVA state > > + * > > No newline > +1 > > + * @dma_state: DMA IOVA state. > > + * @offset: Current offset in IOVA. > > + * > > + * This structure acts as an iterator for packing all IOVA addresses > > within a > > + * contiguous range. > > + */ > > +struct drm_pagemap_iova_state { > > + struct dma_iova_state dma_state; > > + unsigned long offset; > > +}; > > + > >  /** > >   * drm_pagemap_migrate_map_system_pages() - Map system migration > > pages for GPU SVM migration > >   * @dev: The device performing the migration. > > @@ -287,6 +301,7 @@ drm_pagemap_migrate_map_device_pages(struct > > device *dev, > >   * @migrate_pfn: Array of page frame numbers of system pages or peer > > pages to map. > >   * @npages: Number of system pages or peer pages to map. > >   * @dir: Direction of data transfer (e.g., DMA_BIDIRECTIONAL) > > + * @state: DMA IOVA state for mapping. > >   * > >   * This function maps pages of memory for migration usage in GPU > > SVM. It > >   * iterates over each page frame number provided in @migrate_pfn, > > maps the > > @@ -300,9 +315,11 @@ drm_pagemap_migrate_map_system_pages(struct > > device *dev, > >        struct drm_pagemap_addr > > *pagemap_addr, > >        unsigned long *migrate_pfn, > >        unsigned long npages, > > -      enum dma_data_direction dir) > > +      enum dma_data_direction dir, > > +      struct drm_pagemap_iova_state > > *state) > >  { > >   unsigned long i; > > + bool try_alloc = false; > >   > >   for (i = 0; i < npages;) { > >   struct page *page = > > migrate_pfn_to_page(migrate_pfn[i]); > > @@ -317,9 +334,31 @@ drm_pagemap_migrate_map_system_pages(struct > > device *dev, > >   folio = page_folio(page); > >   order = folio_order(folio); > >   > > - dma_addr = dma_map_page(dev, page, 0, > > page_size(page), dir); > > - if (dma_mapping_error(dev, dma_addr)) > > - return -EFAULT; > > + if (!try_alloc) { > > + dma_iova_try_alloc(dev, &state->dma_state, > > +    npages * PAGE_SIZE >= > > +    HPAGE_PMD_SIZE ? > > +    HPAGE_PMD_SIZE : 0, > > +    npages * PAGE_SIZE); > > + try_alloc = true; > > + } > > What happens if dma_iova_try_alloc() fails for all i < some value x and > then suddenly succeeds for i == x? While the below code looks correct, We only try to alloc on the first valid page - 'i' may be any value based on the first page found or we may never alloc if the number of pages found == 0 (possible, hence why it is inside the loop). This step is done at most once. If the allocation fails, we use the map_page path for the remaining loop iterations. > I figure we'd allocate a too large IOVA region and possibly get the > alignment wrong? The first and only IOVA allocation attempts an aligned allocation. What can happen is only a subset of the IOVA is used for the copy but we pack in the pages starting at IOVA[0] and end at IOVA[number valid pages - 1]. Matt > > Otherwise LGTM. > > > > + > > + if (dma_use_iova(&state->dma_state)) { > > + int err = dma_iova_link(dev, &state- > > >dma_state, > > + page_to_phys(page), > > + state->offset, > > page_size(page), > > + dir, 0); > > + if (err) > > + return err; > > + > > + dma_addr = state->dma_state.addr + state- > > >offset; > > + state->offset += page_size(page); > > + } else { > > + dma_addr = dma_map_page(dev, page, 0, > > page_size(page), > > + dir); > > + if (dma_mapping_error(dev, dma_addr)) > > + return -EFAULT; > > + } > >   > >   pagemap_addr[i] = > >   drm_pagemap_addr_encode(dma_addr, > > @@ -330,6 +369,9 @@ drm_pagemap_migrate_map_system_pages(struct > > device *dev, > >   i += NR_PAGES(order); > >   } > >   > > + if (dma_use_iova(&state->dma_state)) > > + return dma_iova_sync(dev, &state->dma_state, 0, > > state->offset); > > + > >   return 0; > >  } > >   > > @@ -341,6 +383,7 @@ drm_pagemap_migrate_map_system_pages(struct > > device *dev, > >   * @pagemap_addr: Array of DMA information corresponding to mapped > > pages > >   * @npages: Number of pages to unmap > >   * @dir: Direction of data transfer (e.g., DMA_BIDIRECTIONAL) > > + * @state: DMA IOVA state for mapping. > >   * > >   * This function unmaps previously mapped pages of memory for GPU > > Shared Virtual > >   * Memory (SVM). It iterates over each DMA address provided in > > @dma_addr, checks > > @@ -350,10 +393,17 @@ static void > > drm_pagemap_migrate_unmap_pages(struct device *dev, > >       struct drm_pagemap_addr > > *pagemap_addr, > >       unsigned long > > *migrate_pfn, > >       unsigned long npages, > > -     enum dma_data_direction > > dir) > > +     enum dma_data_direction > > dir, > > +     struct > > drm_pagemap_iova_state *state) > >  { > >   unsigned long i; > >   > > + if (state && dma_use_iova(&state->dma_state)) { > > + dma_iova_unlink(dev, &state->dma_state, 0, state- > > >offset, dir, 0); > > + dma_iova_free(dev, &state->dma_state); > > + return; > > + } > > + > >   for (i = 0; i < npages;) { > >   struct page *page = > > migrate_pfn_to_page(migrate_pfn[i]); > >   > > @@ -406,7 +456,7 @@ drm_pagemap_migrate_remote_to_local(struct > > drm_pagemap_devmem *devmem, > >          devmem->pre_migrate_fence); > >  out: > >   drm_pagemap_migrate_unmap_pages(remote_device, pagemap_addr, > > local_pfns, > > - npages, DMA_FROM_DEVICE); > > + npages, DMA_FROM_DEVICE, > > NULL); > >   return err; > >  } > >   > > @@ -416,11 +466,13 @@ drm_pagemap_migrate_sys_to_dev(struct > > drm_pagemap_devmem *devmem, > >          struct page *local_pages[], > >          struct drm_pagemap_addr > > pagemap_addr[], > >          unsigned long npages, > > -        const struct drm_pagemap_devmem_ops > > *ops) > > +        const struct drm_pagemap_devmem_ops > > *ops, > > +        struct drm_pagemap_iova_state *state) > >  { > >   int err = drm_pagemap_migrate_map_system_pages(devmem->dev, > >          pagemap_addr, > > sys_pfns, > > -        npages, > > DMA_TO_DEVICE); > > +        npages, > > DMA_TO_DEVICE, > > +        state); > >   > >   if (err) > >   goto out; > > @@ -429,7 +481,7 @@ drm_pagemap_migrate_sys_to_dev(struct > > drm_pagemap_devmem *devmem, > >     devmem->pre_migrate_fence); > >  out: > >   drm_pagemap_migrate_unmap_pages(devmem->dev, pagemap_addr, > > sys_pfns, npages, > > - DMA_TO_DEVICE); > > + DMA_TO_DEVICE, state); > >   return err; > >  } > >   > > @@ -457,6 +509,7 @@ static int drm_pagemap_migrate_range(struct > > drm_pagemap_devmem *devmem, > >        const struct migrate_range_loc > > *cur, > >        const struct > > drm_pagemap_migrate_details *mdetails) > >  { > > + struct drm_pagemap_iova_state state = {}; > >   int ret = 0; > >   > >   if (cur->start == 0) > > @@ -484,7 +537,7 @@ static int drm_pagemap_migrate_range(struct > > drm_pagemap_devmem *devmem, > >        &pages[last- > > >start], > >        > > &pagemap_addr[last->start], > >        cur->start - > > last->start, > > -      last->ops); > > +      last->ops, > > &state); > >   > >  out: > >   *last = *cur; > > @@ -1001,6 +1054,7 @@ EXPORT_SYMBOL(drm_pagemap_put); > >  int drm_pagemap_evict_to_ram(struct drm_pagemap_devmem > > *devmem_allocation) > >  { > >   const struct drm_pagemap_devmem_ops *ops = > > devmem_allocation->ops; > > + struct drm_pagemap_iova_state state = {}; > >   unsigned long npages, mpages = 0; > >   struct page **pages; > >   unsigned long *src, *dst; > > @@ -1042,7 +1096,7 @@ int drm_pagemap_evict_to_ram(struct > > drm_pagemap_devmem *devmem_allocation) > >   err = > > drm_pagemap_migrate_map_system_pages(devmem_allocation->dev, > >      pagemap_addr, > >      dst, npages, > > -    DMA_FROM_DEVICE); > > +    DMA_FROM_DEVICE, > > &state); > >   if (err) > >   goto err_finalize; > >   > > @@ -1059,7 +1113,7 @@ int drm_pagemap_evict_to_ram(struct > > drm_pagemap_devmem *devmem_allocation) > >   migrate_device_pages(src, dst, npages); > >   migrate_device_finalize(src, dst, npages); > >   drm_pagemap_migrate_unmap_pages(devmem_allocation->dev, > > pagemap_addr, dst, npages, > > - DMA_FROM_DEVICE); > > + DMA_FROM_DEVICE, &state); > >   > >  err_free: > >   kvfree(buf); > > @@ -1103,6 +1157,7 @@ static int __drm_pagemap_migrate_to_ram(struct > > vm_area_struct *vas, > >   MIGRATE_VMA_SELECT_DEVICE_COHERENT, > >   .fault_page = page, > >   }; > > + struct drm_pagemap_iova_state state = {}; > >   struct drm_pagemap_zdd *zdd; > >   const struct drm_pagemap_devmem_ops *ops; > >   struct device *dev = NULL; > > @@ -1162,7 +1217,7 @@ static int __drm_pagemap_migrate_to_ram(struct > > vm_area_struct *vas, > >   > >   err = drm_pagemap_migrate_map_system_pages(dev, > > pagemap_addr, > >      migrate.dst, > > npages, > > -    DMA_FROM_DEVICE); > > +    DMA_FROM_DEVICE, > > &state); > >   if (err) > >   goto err_finalize; > >   > > @@ -1180,7 +1235,8 @@ static int __drm_pagemap_migrate_to_ram(struct > > vm_area_struct *vas, > >   migrate_vma_finalize(&migrate); > >   if (dev) > >   drm_pagemap_migrate_unmap_pages(dev, pagemap_addr, > > migrate.dst, > > - npages, > > DMA_FROM_DEVICE); > > + npages, > > DMA_FROM_DEVICE, > > + &state); > >  err_free: > >   kvfree(buf); > >  err_out: