Re: [Intel-gfx] [PATCH 13/28] drm/i915: Remove pages_mutex and intel_gtt->vma_ops.set/clear_pages members

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On 22-10-2021 12:59, Matthew Auld wrote:
> On Thu, 21 Oct 2021 at 18:30, Matthew Auld
> <matthew.william.auld@xxxxxxxxx> wrote:
>> On Thu, 21 Oct 2021 at 11:36, Maarten Lankhorst
>> <maarten.lankhorst@xxxxxxxxxxxxxxx> wrote:
>>> Big delta, but boils down to moving set_pages to i915_vma.c, and removing
>>> the special handling, all callers use the defaults anyway. We only remap
>>> in ggtt, so default case will fall through.
>>>
>>> Because we still don't require locking in i915_vma_unpin(), handle this by
>>> using xchg in get_pages(), as it's locked with obj->mutex, and cmpxchg in
>>> unpin, which only fails if we race a against a new pin.
>>>
>>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
>>> ---
>>>  drivers/gpu/drm/i915/display/intel_dpt.c      |   2 -
>>>  drivers/gpu/drm/i915/gt/gen6_ppgtt.c          |  15 -
>>>  drivers/gpu/drm/i915/gt/intel_ggtt.c          | 345 ----------------
>>>  drivers/gpu/drm/i915/gt/intel_gtt.c           |  13 -
>>>  drivers/gpu/drm/i915/gt/intel_gtt.h           |   7 -
>>>  drivers/gpu/drm/i915/gt/intel_ppgtt.c         |  12 -
>>>  drivers/gpu/drm/i915/i915_vma.c               | 388 ++++++++++++++++--
>>>  drivers/gpu/drm/i915/i915_vma.h               |   3 +
>>>  drivers/gpu/drm/i915/i915_vma_types.h         |   1 -
>>>  drivers/gpu/drm/i915/selftests/i915_gem_gtt.c |  12 +-
>>>  drivers/gpu/drm/i915/selftests/mock_gtt.c     |   4 -
>>>  11 files changed, 368 insertions(+), 434 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/display/intel_dpt.c b/drivers/gpu/drm/i915/display/intel_dpt.c
>>> index 8f7b1f7534a4..ef428f3fc538 100644
>>> --- a/drivers/gpu/drm/i915/display/intel_dpt.c
>>> +++ b/drivers/gpu/drm/i915/display/intel_dpt.c
>>> @@ -221,8 +221,6 @@ intel_dpt_create(struct intel_framebuffer *fb)
>>>
>>>         vm->vma_ops.bind_vma    = dpt_bind_vma;
>>>         vm->vma_ops.unbind_vma  = dpt_unbind_vma;
>>> -       vm->vma_ops.set_pages   = ggtt_set_pages;
>>> -       vm->vma_ops.clear_pages = clear_pages;
>>>
>>>         vm->pte_encode = gen8_ggtt_pte_encode;
>>>
>>> diff --git a/drivers/gpu/drm/i915/gt/gen6_ppgtt.c b/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
>>> index 5caa1703716e..5c048b4ccd4d 100644
>>> --- a/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
>>> +++ b/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
>>> @@ -270,19 +270,6 @@ static void gen6_ppgtt_cleanup(struct i915_address_space *vm)
>>>         free_pd(&ppgtt->base.vm, ppgtt->base.pd);
>>>  }
>>>
>>> -static int pd_vma_set_pages(struct i915_vma *vma)
>>> -{
>>> -       vma->pages = ERR_PTR(-ENODEV);
>>> -       return 0;
>>> -}
>>> -
>>> -static void pd_vma_clear_pages(struct i915_vma *vma)
>>> -{
>>> -       GEM_BUG_ON(!vma->pages);
>>> -
>>> -       vma->pages = NULL;
>>> -}
>>> -
>>>  static void pd_vma_bind(struct i915_address_space *vm,
>>>                         struct i915_vm_pt_stash *stash,
>>>                         struct i915_vma *vma,
>>> @@ -322,8 +309,6 @@ static void pd_vma_unbind(struct i915_address_space *vm, struct i915_vma *vma)
>>>  }
>>>
>>>  static const struct i915_vma_ops pd_vma_ops = {
>>> -       .set_pages = pd_vma_set_pages,
>>> -       .clear_pages = pd_vma_clear_pages,
>>>         .bind_vma = pd_vma_bind,
>>>         .unbind_vma = pd_vma_unbind,
>>>  };
>>> diff --git a/drivers/gpu/drm/i915/gt/intel_ggtt.c b/drivers/gpu/drm/i915/gt/intel_ggtt.c
>>> index f17383e76eb7..6da57199bb33 100644
>>> --- a/drivers/gpu/drm/i915/gt/intel_ggtt.c
>>> +++ b/drivers/gpu/drm/i915/gt/intel_ggtt.c
>>> @@ -20,9 +20,6 @@
>>>  #include "intel_gtt.h"
>>>  #include "gen8_ppgtt.h"
>>>
>>> -static int
>>> -i915_get_ggtt_vma_pages(struct i915_vma *vma);
>>> -
>>>  static void i915_ggtt_color_adjust(const struct drm_mm_node *node,
>>>                                    unsigned long color,
>>>                                    u64 *start,
>>> @@ -875,21 +872,6 @@ static int ggtt_probe_common(struct i915_ggtt *ggtt, u64 size)
>>>         return 0;
>>>  }
>>>
>>> -int ggtt_set_pages(struct i915_vma *vma)
>>> -{
>>> -       int ret;
>>> -
>>> -       GEM_BUG_ON(vma->pages);
>>> -
>>> -       ret = i915_get_ggtt_vma_pages(vma);
>>> -       if (ret)
>>> -               return ret;
>>> -
>>> -       vma->page_sizes = vma->obj->mm.page_sizes;
>>> -
>>> -       return 0;
>>> -}
>>> -
>>>  static void gen6_gmch_remove(struct i915_address_space *vm)
>>>  {
>>>         struct i915_ggtt *ggtt = i915_vm_to_ggtt(vm);
>>> @@ -950,8 +932,6 @@ static int gen8_gmch_probe(struct i915_ggtt *ggtt)
>>>
>>>         ggtt->vm.vma_ops.bind_vma    = ggtt_bind_vma;
>>>         ggtt->vm.vma_ops.unbind_vma  = ggtt_unbind_vma;
>>> -       ggtt->vm.vma_ops.set_pages   = ggtt_set_pages;
>>> -       ggtt->vm.vma_ops.clear_pages = clear_pages;
>>>
>>>         ggtt->vm.pte_encode = gen8_ggtt_pte_encode;
>>>
>>> @@ -1100,8 +1080,6 @@ static int gen6_gmch_probe(struct i915_ggtt *ggtt)
>>>
>>>         ggtt->vm.vma_ops.bind_vma    = ggtt_bind_vma;
>>>         ggtt->vm.vma_ops.unbind_vma  = ggtt_unbind_vma;
>>> -       ggtt->vm.vma_ops.set_pages   = ggtt_set_pages;
>>> -       ggtt->vm.vma_ops.clear_pages = clear_pages;
>>>
>>>         return ggtt_probe_common(ggtt, size);
>>>  }
>>> @@ -1145,8 +1123,6 @@ static int i915_gmch_probe(struct i915_ggtt *ggtt)
>>>
>>>         ggtt->vm.vma_ops.bind_vma    = ggtt_bind_vma;
>>>         ggtt->vm.vma_ops.unbind_vma  = ggtt_unbind_vma;
>>> -       ggtt->vm.vma_ops.set_pages   = ggtt_set_pages;
>>> -       ggtt->vm.vma_ops.clear_pages = clear_pages;
>>>
>>>         if (unlikely(ggtt->do_idle_maps))
>>>                 drm_notice(&i915->drm,
>>> @@ -1294,324 +1270,3 @@ void i915_ggtt_resume(struct i915_ggtt *ggtt)
>>>
>>>         intel_ggtt_restore_fences(ggtt);
>>>  }
>>> -
>>> -static struct scatterlist *
>>> -rotate_pages(struct drm_i915_gem_object *obj, unsigned int offset,
>>> -            unsigned int width, unsigned int height,
>>> -            unsigned int src_stride, unsigned int dst_stride,
>>> -            struct sg_table *st, struct scatterlist *sg)
>>> -{
>>> -       unsigned int column, row;
>>> -       unsigned int src_idx;
>>> -
>>> -       for (column = 0; column < width; column++) {
>>> -               unsigned int left;
>>> -
>>> -               src_idx = src_stride * (height - 1) + column + offset;
>>> -               for (row = 0; row < height; row++) {
>>> -                       st->nents++;
>>> -                       /*
>>> -                        * We don't need the pages, but need to initialize
>>> -                        * the entries so the sg list can be happily traversed.
>>> -                        * The only thing we need are DMA addresses.
>>> -                        */
>>> -                       sg_set_page(sg, NULL, I915_GTT_PAGE_SIZE, 0);
>>> -                       sg_dma_address(sg) =
>>> -                               i915_gem_object_get_dma_address(obj, src_idx);
>>> -                       sg_dma_len(sg) = I915_GTT_PAGE_SIZE;
>>> -                       sg = sg_next(sg);
>>> -                       src_idx -= src_stride;
>>> -               }
>>> -
>>> -               left = (dst_stride - height) * I915_GTT_PAGE_SIZE;
>>> -
>>> -               if (!left)
>>> -                       continue;
>>> -
>>> -               st->nents++;
>>> -
>>> -               /*
>>> -                * The DE ignores the PTEs for the padding tiles, the sg entry
>>> -                * here is just a conenience to indicate how many padding PTEs
>>> -                * to insert at this spot.
>>> -                */
>>> -               sg_set_page(sg, NULL, left, 0);
>>> -               sg_dma_address(sg) = 0;
>>> -               sg_dma_len(sg) = left;
>>> -               sg = sg_next(sg);
>>> -       }
>>> -
>>> -       return sg;
>>> -}
>>> -
>>> -static noinline struct sg_table *
>>> -intel_rotate_pages(struct intel_rotation_info *rot_info,
>>> -                  struct drm_i915_gem_object *obj)
>>> -{
>>> -       unsigned int size = intel_rotation_info_size(rot_info);
>>> -       struct drm_i915_private *i915 = to_i915(obj->base.dev);
>>> -       struct sg_table *st;
>>> -       struct scatterlist *sg;
>>> -       int ret = -ENOMEM;
>>> -       int i;
>>> -
>>> -       /* Allocate target SG list. */
>>> -       st = kmalloc(sizeof(*st), GFP_KERNEL);
>>> -       if (!st)
>>> -               goto err_st_alloc;
>>> -
>>> -       ret = sg_alloc_table(st, size, GFP_KERNEL);
>>> -       if (ret)
>>> -               goto err_sg_alloc;
>>> -
>>> -       st->nents = 0;
>>> -       sg = st->sgl;
>>> -
>>> -       for (i = 0 ; i < ARRAY_SIZE(rot_info->plane); i++)
>>> -               sg = rotate_pages(obj, rot_info->plane[i].offset,
>>> -                                 rot_info->plane[i].width, rot_info->plane[i].height,
>>> -                                 rot_info->plane[i].src_stride,
>>> -                                 rot_info->plane[i].dst_stride,
>>> -                                 st, sg);
>>> -
>>> -       return st;
>>> -
>>> -err_sg_alloc:
>>> -       kfree(st);
>>> -err_st_alloc:
>>> -
>>> -       drm_dbg(&i915->drm, "Failed to create rotated mapping for object size %zu! (%ux%u tiles, %u pages)\n",
>>> -               obj->base.size, rot_info->plane[0].width,
>>> -               rot_info->plane[0].height, size);
>>> -
>>> -       return ERR_PTR(ret);
>>> -}
>>> -
>>> -static struct scatterlist *
>>> -remap_pages(struct drm_i915_gem_object *obj,
>>> -           unsigned int offset, unsigned int alignment_pad,
>>> -           unsigned int width, unsigned int height,
>>> -           unsigned int src_stride, unsigned int dst_stride,
>>> -           struct sg_table *st, struct scatterlist *sg)
>>> -{
>>> -       unsigned int row;
>>> -
>>> -       if (alignment_pad) {
>>> -               st->nents++;
>>> -
>>> -               /*
>>> -                * The DE ignores the PTEs for the padding tiles, the sg entry
>>> -                * here is just a convenience to indicate how many padding PTEs
>>> -                * to insert at this spot.
>>> -                */
>>> -               sg_set_page(sg, NULL, alignment_pad * 4096, 0);
>>> -               sg_dma_address(sg) = 0;
>>> -               sg_dma_len(sg) = alignment_pad * 4096;
>>> -               sg = sg_next(sg);
>>> -       }
>>> -
>>> -       for (row = 0; row < height; row++) {
>>> -               unsigned int left = width * I915_GTT_PAGE_SIZE;
>>> -
>>> -               while (left) {
>>> -                       dma_addr_t addr;
>>> -                       unsigned int length;
>>> -
>>> -                       /*
>>> -                        * We don't need the pages, but need to initialize
>>> -                        * the entries so the sg list can be happily traversed.
>>> -                        * The only thing we need are DMA addresses.
>>> -                        */
>>> -
>>> -                       addr = i915_gem_object_get_dma_address_len(obj, offset, &length);
>>> -
>>> -                       length = min(left, length);
>>> -
>>> -                       st->nents++;
>>> -
>>> -                       sg_set_page(sg, NULL, length, 0);
>>> -                       sg_dma_address(sg) = addr;
>>> -                       sg_dma_len(sg) = length;
>>> -                       sg = sg_next(sg);
>>> -
>>> -                       offset += length / I915_GTT_PAGE_SIZE;
>>> -                       left -= length;
>>> -               }
>>> -
>>> -               offset += src_stride - width;
>>> -
>>> -               left = (dst_stride - width) * I915_GTT_PAGE_SIZE;
>>> -
>>> -               if (!left)
>>> -                       continue;
>>> -
>>> -               st->nents++;
>>> -
>>> -               /*
>>> -                * The DE ignores the PTEs for the padding tiles, the sg entry
>>> -                * here is just a conenience to indicate how many padding PTEs
>>> -                * to insert at this spot.
>>> -                */
>>> -               sg_set_page(sg, NULL, left, 0);
>>> -               sg_dma_address(sg) = 0;
>>> -               sg_dma_len(sg) = left;
>>> -               sg = sg_next(sg);
>>> -       }
>>> -
>>> -       return sg;
>>> -}
>>> -
>>> -static noinline struct sg_table *
>>> -intel_remap_pages(struct intel_remapped_info *rem_info,
>>> -                 struct drm_i915_gem_object *obj)
>>> -{
>>> -       unsigned int size = intel_remapped_info_size(rem_info);
>>> -       struct drm_i915_private *i915 = to_i915(obj->base.dev);
>>> -       struct sg_table *st;
>>> -       struct scatterlist *sg;
>>> -       unsigned int gtt_offset = 0;
>>> -       int ret = -ENOMEM;
>>> -       int i;
>>> -
>>> -       /* Allocate target SG list. */
>>> -       st = kmalloc(sizeof(*st), GFP_KERNEL);
>>> -       if (!st)
>>> -               goto err_st_alloc;
>>> -
>>> -       ret = sg_alloc_table(st, size, GFP_KERNEL);
>>> -       if (ret)
>>> -               goto err_sg_alloc;
>>> -
>>> -       st->nents = 0;
>>> -       sg = st->sgl;
>>> -
>>> -       for (i = 0 ; i < ARRAY_SIZE(rem_info->plane); i++) {
>>> -               unsigned int alignment_pad = 0;
>>> -
>>> -               if (rem_info->plane_alignment)
>>> -                       alignment_pad = ALIGN(gtt_offset, rem_info->plane_alignment) - gtt_offset;
>>> -
>>> -               sg = remap_pages(obj,
>>> -                                rem_info->plane[i].offset, alignment_pad,
>>> -                                rem_info->plane[i].width, rem_info->plane[i].height,
>>> -                                rem_info->plane[i].src_stride, rem_info->plane[i].dst_stride,
>>> -                                st, sg);
>>> -
>>> -               gtt_offset += alignment_pad +
>>> -                             rem_info->plane[i].dst_stride * rem_info->plane[i].height;
>>> -       }
>>> -
>>> -       i915_sg_trim(st);
>>> -
>>> -       return st;
>>> -
>>> -err_sg_alloc:
>>> -       kfree(st);
>>> -err_st_alloc:
>>> -
>>> -       drm_dbg(&i915->drm, "Failed to create remapped mapping for object size %zu! (%ux%u tiles, %u pages)\n",
>>> -               obj->base.size, rem_info->plane[0].width,
>>> -               rem_info->plane[0].height, size);
>>> -
>>> -       return ERR_PTR(ret);
>>> -}
>>> -
>>> -static noinline struct sg_table *
>>> -intel_partial_pages(const struct i915_ggtt_view *view,
>>> -                   struct drm_i915_gem_object *obj)
>>> -{
>>> -       struct sg_table *st;
>>> -       struct scatterlist *sg, *iter;
>>> -       unsigned int count = view->partial.size;
>>> -       unsigned int offset;
>>> -       int ret = -ENOMEM;
>>> -
>>> -       st = kmalloc(sizeof(*st), GFP_KERNEL);
>>> -       if (!st)
>>> -               goto err_st_alloc;
>>> -
>>> -       ret = sg_alloc_table(st, count, GFP_KERNEL);
>>> -       if (ret)
>>> -               goto err_sg_alloc;
>>> -
>>> -       iter = i915_gem_object_get_sg_dma(obj, view->partial.offset, &offset);
>>> -       GEM_BUG_ON(!iter);
>>> -
>>> -       sg = st->sgl;
>>> -       st->nents = 0;
>>> -       do {
>>> -               unsigned int len;
>>> -
>>> -               len = min(sg_dma_len(iter) - (offset << PAGE_SHIFT),
>>> -                         count << PAGE_SHIFT);
>>> -               sg_set_page(sg, NULL, len, 0);
>>> -               sg_dma_address(sg) =
>>> -                       sg_dma_address(iter) + (offset << PAGE_SHIFT);
>>> -               sg_dma_len(sg) = len;
>>> -
>>> -               st->nents++;
>>> -               count -= len >> PAGE_SHIFT;
>>> -               if (count == 0) {
>>> -                       sg_mark_end(sg);
>>> -                       i915_sg_trim(st); /* Drop any unused tail entries. */
>>> -
>>> -                       return st;
>>> -               }
>>> -
>>> -               sg = __sg_next(sg);
>>> -               iter = __sg_next(iter);
>>> -               offset = 0;
>>> -       } while (1);
>>> -
>>> -err_sg_alloc:
>>> -       kfree(st);
>>> -err_st_alloc:
>>> -       return ERR_PTR(ret);
>>> -}
>>> -
>>> -static int
>>> -i915_get_ggtt_vma_pages(struct i915_vma *vma)
>>> -{
>>> -       int ret;
>>> -
>>> -       /*
>>> -        * The vma->pages are only valid within the lifespan of the borrowed
>>> -        * obj->mm.pages. When the obj->mm.pages sg_table is regenerated, so
>>> -        * must be the vma->pages. A simple rule is that vma->pages must only
>>> -        * be accessed when the obj->mm.pages are pinned.
>>> -        */
>>> -       GEM_BUG_ON(!i915_gem_object_has_pinned_pages(vma->obj));
>>> -
>>> -       switch (vma->ggtt_view.type) {
>>> -       default:
>>> -               GEM_BUG_ON(vma->ggtt_view.type);
>>> -               fallthrough;
>>> -       case I915_GGTT_VIEW_NORMAL:
>>> -               vma->pages = vma->obj->mm.pages;
>>> -               return 0;
>>> -
>>> -       case I915_GGTT_VIEW_ROTATED:
>>> -               vma->pages =
>>> -                       intel_rotate_pages(&vma->ggtt_view.rotated, vma->obj);
>>> -               break;
>>> -
>>> -       case I915_GGTT_VIEW_REMAPPED:
>>> -               vma->pages =
>>> -                       intel_remap_pages(&vma->ggtt_view.remapped, vma->obj);
>>> -               break;
>>> -
>>> -       case I915_GGTT_VIEW_PARTIAL:
>>> -               vma->pages = intel_partial_pages(&vma->ggtt_view, vma->obj);
>>> -               break;
>>> -       }
>>> -
>>> -       ret = 0;
>>> -       if (IS_ERR(vma->pages)) {
>>> -               ret = PTR_ERR(vma->pages);
>>> -               vma->pages = NULL;
>>> -               drm_err(&vma->vm->i915->drm,
>>> -                       "Failed to get pages for VMA view type %u (%d)!\n",
>>> -                       vma->ggtt_view.type, ret);
>>> -       }
>>> -       return ret;
>>> -}
>>> diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.c b/drivers/gpu/drm/i915/gt/intel_gtt.c
>>> index 67d14afa6623..12eed5fcb17a 100644
>>> --- a/drivers/gpu/drm/i915/gt/intel_gtt.c
>>> +++ b/drivers/gpu/drm/i915/gt/intel_gtt.c
>>> @@ -221,19 +221,6 @@ void i915_address_space_init(struct i915_address_space *vm, int subclass)
>>>         INIT_LIST_HEAD(&vm->bound_list);
>>>  }
>>>
>>> -void clear_pages(struct i915_vma *vma)
>>> -{
>>> -       GEM_BUG_ON(!vma->pages);
>>> -
>>> -       if (vma->pages != vma->obj->mm.pages) {
>>> -               sg_free_table(vma->pages);
>>> -               kfree(vma->pages);
>>> -       }
>>> -       vma->pages = NULL;
>>> -
>>> -       memset(&vma->page_sizes, 0, sizeof(vma->page_sizes));
>>> -}
>>> -
>>>  void *__px_vaddr(struct drm_i915_gem_object *p)
>>>  {
>>>         enum i915_map_type type;
>>> diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.h b/drivers/gpu/drm/i915/gt/intel_gtt.h
>>> index bc6750263359..306e7645fdc5 100644
>>> --- a/drivers/gpu/drm/i915/gt/intel_gtt.h
>>> +++ b/drivers/gpu/drm/i915/gt/intel_gtt.h
>>> @@ -206,9 +206,6 @@ struct i915_vma_ops {
>>>          */
>>>         void (*unbind_vma)(struct i915_address_space *vm,
>>>                            struct i915_vma *vma);
>>> -
>>> -       int (*set_pages)(struct i915_vma *vma);
>>> -       void (*clear_pages)(struct i915_vma *vma);
>>>  };
>>>
>>>  struct i915_address_space {
>>> @@ -594,10 +591,6 @@ release_pd_entry(struct i915_page_directory * const pd,
>>>                  const struct drm_i915_gem_object * const scratch);
>>>  void gen6_ggtt_invalidate(struct i915_ggtt *ggtt);
>>>
>>> -int ggtt_set_pages(struct i915_vma *vma);
>>> -int ppgtt_set_pages(struct i915_vma *vma);
>>> -void clear_pages(struct i915_vma *vma);
>>> -
>>>  void ppgtt_bind_vma(struct i915_address_space *vm,
>>>                     struct i915_vm_pt_stash *stash,
>>>                     struct i915_vma *vma,
>>> diff --git a/drivers/gpu/drm/i915/gt/intel_ppgtt.c b/drivers/gpu/drm/i915/gt/intel_ppgtt.c
>>> index 4396bfd630d8..083b3090c69c 100644
>>> --- a/drivers/gpu/drm/i915/gt/intel_ppgtt.c
>>> +++ b/drivers/gpu/drm/i915/gt/intel_ppgtt.c
>>> @@ -289,16 +289,6 @@ void i915_vm_free_pt_stash(struct i915_address_space *vm,
>>>         }
>>>  }
>>>
>>> -int ppgtt_set_pages(struct i915_vma *vma)
>>> -{
>>> -       GEM_BUG_ON(vma->pages);
>>> -
>>> -       vma->pages = vma->obj->mm.pages;
>>> -       vma->page_sizes = vma->obj->mm.page_sizes;
>>> -
>>> -       return 0;
>>> -}
>>> -
>>>  void ppgtt_init(struct i915_ppgtt *ppgtt, struct intel_gt *gt,
>>>                 unsigned long lmem_pt_obj_flags)
>>>  {
>>> @@ -315,6 +305,4 @@ void ppgtt_init(struct i915_ppgtt *ppgtt, struct intel_gt *gt,
>>>
>>>         ppgtt->vm.vma_ops.bind_vma    = ppgtt_bind_vma;
>>>         ppgtt->vm.vma_ops.unbind_vma  = ppgtt_unbind_vma;
>>> -       ppgtt->vm.vma_ops.set_pages   = ppgtt_set_pages;
>>> -       ppgtt->vm.vma_ops.clear_pages = clear_pages;
>>>  }
>>> diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
>>> index ac09b685678a..bacc8d68e495 100644
>>> --- a/drivers/gpu/drm/i915/i915_vma.c
>>> +++ b/drivers/gpu/drm/i915/i915_vma.c
>>> @@ -112,7 +112,6 @@ vma_create(struct drm_i915_gem_object *obj,
>>>                 return ERR_PTR(-ENOMEM);
>>>
>>>         kref_init(&vma->ref);
>>> -       mutex_init(&vma->pages_mutex);
>>>         vma->vm = i915_vm_get(vm);
>>>         vma->ops = &vm->vma_ops;
>>>         vma->obj = obj;
>>> @@ -789,10 +788,343 @@ static bool try_qad_pin(struct i915_vma *vma, unsigned int flags)
>>>         return pinned;
>>>  }
>>>
>>> -static int vma_get_pages(struct i915_vma *vma)
>>> +
>>> +
>>> +static struct scatterlist *
>>> +rotate_pages(struct drm_i915_gem_object *obj, unsigned int offset,
>>> +            unsigned int width, unsigned int height,
>>> +            unsigned int src_stride, unsigned int dst_stride,
>>> +            struct sg_table *st, struct scatterlist *sg)
>>>  {
>>> -       int err = 0;
>>> -       bool pinned_pages = true;
>>> +       unsigned int column, row;
>>> +       unsigned int src_idx;
>>> +
>>> +       for (column = 0; column < width; column++) {
>>> +               unsigned int left;
>>> +
>>> +               src_idx = src_stride * (height - 1) + column + offset;
>>> +               for (row = 0; row < height; row++) {
>>> +                       st->nents++;
>>> +                       /*
>>> +                        * We don't need the pages, but need to initialize
>>> +                        * the entries so the sg list can be happily traversed.
>>> +                        * The only thing we need are DMA addresses.
>>> +                        */
>>> +                       sg_set_page(sg, NULL, I915_GTT_PAGE_SIZE, 0);
>>> +                       sg_dma_address(sg) =
>>> +                               i915_gem_object_get_dma_address(obj, src_idx);
>>> +                       sg_dma_len(sg) = I915_GTT_PAGE_SIZE;
>>> +                       sg = sg_next(sg);
>>> +                       src_idx -= src_stride;
>>> +               }
>>> +
>>> +               left = (dst_stride - height) * I915_GTT_PAGE_SIZE;
>>> +
>>> +               if (!left)
>>> +                       continue;
>>> +
>>> +               st->nents++;
>>> +
>>> +               /*
>>> +                * The DE ignores the PTEs for the padding tiles, the sg entry
>>> +                * here is just a conenience to indicate how many padding PTEs
>>> +                * to insert at this spot.
>>> +                */
>>> +               sg_set_page(sg, NULL, left, 0);
>>> +               sg_dma_address(sg) = 0;
>>> +               sg_dma_len(sg) = left;
>>> +               sg = sg_next(sg);
>>> +       }
>>> +
>>> +       return sg;
>>> +}
>>> +
>>> +static noinline struct sg_table *
>>> +intel_rotate_pages(struct intel_rotation_info *rot_info,
>>> +                  struct drm_i915_gem_object *obj)
>>> +{
>>> +       unsigned int size = intel_rotation_info_size(rot_info);
>>> +       struct drm_i915_private *i915 = to_i915(obj->base.dev);
>>> +       struct sg_table *st;
>>> +       struct scatterlist *sg;
>>> +       int ret = -ENOMEM;
>>> +       int i;
>>> +
>>> +       /* Allocate target SG list. */
>>> +       st = kmalloc(sizeof(*st), GFP_KERNEL);
>>> +       if (!st)
>>> +               goto err_st_alloc;
>>> +
>>> +       ret = sg_alloc_table(st, size, GFP_KERNEL);
>>> +       if (ret)
>>> +               goto err_sg_alloc;
>>> +
>>> +       st->nents = 0;
>>> +       sg = st->sgl;
>>> +
>>> +       for (i = 0 ; i < ARRAY_SIZE(rot_info->plane); i++)
>>> +               sg = rotate_pages(obj, rot_info->plane[i].offset,
>>> +                                 rot_info->plane[i].width, rot_info->plane[i].height,
>>> +                                 rot_info->plane[i].src_stride,
>>> +                                 rot_info->plane[i].dst_stride,
>>> +                                 st, sg);
>>> +
>>> +       return st;
>>> +
>>> +err_sg_alloc:
>>> +       kfree(st);
>>> +err_st_alloc:
>>> +
>>> +       drm_dbg(&i915->drm, "Failed to create rotated mapping for object size %zu! (%ux%u tiles, %u pages)\n",
>>> +               obj->base.size, rot_info->plane[0].width,
>>> +               rot_info->plane[0].height, size);
>>> +
>>> +       return ERR_PTR(ret);
>>> +}
>>> +
>>> +static struct scatterlist *
>>> +remap_pages(struct drm_i915_gem_object *obj,
>>> +           unsigned int offset, unsigned int alignment_pad,
>>> +           unsigned int width, unsigned int height,
>>> +           unsigned int src_stride, unsigned int dst_stride,
>>> +           struct sg_table *st, struct scatterlist *sg)
>>> +{
>>> +       unsigned int row;
>>> +
>>> +       if (alignment_pad) {
>>> +               st->nents++;
>>> +
>>> +               /*
>>> +                * The DE ignores the PTEs for the padding tiles, the sg entry
>>> +                * here is just a convenience to indicate how many padding PTEs
>>> +                * to insert at this spot.
>>> +                */
>>> +               sg_set_page(sg, NULL, alignment_pad * 4096, 0);
>>> +               sg_dma_address(sg) = 0;
>>> +               sg_dma_len(sg) = alignment_pad * 4096;
>>> +               sg = sg_next(sg);
>>> +       }
>>> +
>>> +       for (row = 0; row < height; row++) {
>>> +               unsigned int left = width * I915_GTT_PAGE_SIZE;
>>> +
>>> +               while (left) {
>>> +                       dma_addr_t addr;
>>> +                       unsigned int length;
>>> +
>>> +                       /*
>>> +                        * We don't need the pages, but need to initialize
>>> +                        * the entries so the sg list can be happily traversed.
>>> +                        * The only thing we need are DMA addresses.
>>> +                        */
>>> +
>>> +                       addr = i915_gem_object_get_dma_address_len(obj, offset, &length);
>>> +
>>> +                       length = min(left, length);
>>> +
>>> +                       st->nents++;
>>> +
>>> +                       sg_set_page(sg, NULL, length, 0);
>>> +                       sg_dma_address(sg) = addr;
>>> +                       sg_dma_len(sg) = length;
>>> +                       sg = sg_next(sg);
>>> +
>>> +                       offset += length / I915_GTT_PAGE_SIZE;
>>> +                       left -= length;
>>> +               }
>>> +
>>> +               offset += src_stride - width;
>>> +
>>> +               left = (dst_stride - width) * I915_GTT_PAGE_SIZE;
>>> +
>>> +               if (!left)
>>> +                       continue;
>>> +
>>> +               st->nents++;
>>> +
>>> +               /*
>>> +                * The DE ignores the PTEs for the padding tiles, the sg entry
>>> +                * here is just a conenience to indicate how many padding PTEs
>>> +                * to insert at this spot.
>>> +                */
>>> +               sg_set_page(sg, NULL, left, 0);
>>> +               sg_dma_address(sg) = 0;
>>> +               sg_dma_len(sg) = left;
>>> +               sg = sg_next(sg);
>>> +       }
>>> +
>>> +       return sg;
>>> +}
>>> +
>>> +static noinline struct sg_table *
>>> +intel_remap_pages(struct intel_remapped_info *rem_info,
>>> +                 struct drm_i915_gem_object *obj)
>>> +{
>>> +       unsigned int size = intel_remapped_info_size(rem_info);
>>> +       struct drm_i915_private *i915 = to_i915(obj->base.dev);
>>> +       struct sg_table *st;
>>> +       struct scatterlist *sg;
>>> +       unsigned int gtt_offset = 0;
>>> +       int ret = -ENOMEM;
>>> +       int i;
>>> +
>>> +       /* Allocate target SG list. */
>>> +       st = kmalloc(sizeof(*st), GFP_KERNEL);
>>> +       if (!st)
>>> +               goto err_st_alloc;
>>> +
>>> +       ret = sg_alloc_table(st, size, GFP_KERNEL);
>>> +       if (ret)
>>> +               goto err_sg_alloc;
>>> +
>>> +       st->nents = 0;
>>> +       sg = st->sgl;
>>> +
>>> +       for (i = 0 ; i < ARRAY_SIZE(rem_info->plane); i++) {
>>> +               unsigned int alignment_pad = 0;
>>> +
>>> +               if (rem_info->plane_alignment)
>>> +                       alignment_pad = ALIGN(gtt_offset, rem_info->plane_alignment) - gtt_offset;
>>> +
>>> +               sg = remap_pages(obj,
>>> +                                rem_info->plane[i].offset, alignment_pad,
>>> +                                rem_info->plane[i].width, rem_info->plane[i].height,
>>> +                                rem_info->plane[i].src_stride, rem_info->plane[i].dst_stride,
>>> +                                st, sg);
>>> +
>>> +               gtt_offset += alignment_pad +
>>> +                             rem_info->plane[i].dst_stride * rem_info->plane[i].height;
>>> +       }
>>> +
>>> +       i915_sg_trim(st);
>>> +
>>> +       return st;
>>> +
>>> +err_sg_alloc:
>>> +       kfree(st);
>>> +err_st_alloc:
>>> +
>>> +       drm_dbg(&i915->drm, "Failed to create remapped mapping for object size %zu! (%ux%u tiles, %u pages)\n",
>>> +               obj->base.size, rem_info->plane[0].width,
>>> +               rem_info->plane[0].height, size);
>>> +
>>> +       return ERR_PTR(ret);
>>> +}
>>> +
>>> +static noinline struct sg_table *
>>> +intel_partial_pages(const struct i915_ggtt_view *view,
>>> +                   struct drm_i915_gem_object *obj)
>>> +{
>>> +       struct sg_table *st;
>>> +       struct scatterlist *sg, *iter;
>>> +       unsigned int count = view->partial.size;
>>> +       unsigned int offset;
>>> +       int ret = -ENOMEM;
>>> +
>>> +       st = kmalloc(sizeof(*st), GFP_KERNEL);
>>> +       if (!st)
>>> +               goto err_st_alloc;
>>> +
>>> +       ret = sg_alloc_table(st, count, GFP_KERNEL);
>>> +       if (ret)
>>> +               goto err_sg_alloc;
>>> +
>>> +       iter = i915_gem_object_get_sg_dma(obj, view->partial.offset, &offset);
>>> +       GEM_BUG_ON(!iter);
>>> +
>>> +       sg = st->sgl;
>>> +       st->nents = 0;
>>> +       do {
>>> +               unsigned int len;
>>> +
>>> +               len = min(sg_dma_len(iter) - (offset << PAGE_SHIFT),
>>> +                         count << PAGE_SHIFT);
>>> +               sg_set_page(sg, NULL, len, 0);
>>> +               sg_dma_address(sg) =
>>> +                       sg_dma_address(iter) + (offset << PAGE_SHIFT);
>>> +               sg_dma_len(sg) = len;
>>> +
>>> +               st->nents++;
>>> +               count -= len >> PAGE_SHIFT;
>>> +               if (count == 0) {
>>> +                       sg_mark_end(sg);
>>> +                       i915_sg_trim(st); /* Drop any unused tail entries. */
>>> +
>>> +                       return st;
>>> +               }
>>> +
>>> +               sg = __sg_next(sg);
>>> +               iter = __sg_next(iter);
>>> +               offset = 0;
>>> +       } while (1);
>>> +
>>> +err_sg_alloc:
>>> +       kfree(st);
>>> +err_st_alloc:
>>> +       return ERR_PTR(ret);
>>> +}
>>> +
>>> +static int
>>> +__i915_vma_get_pages(struct i915_vma *vma)
>>> +{
>>> +       struct sg_table *pages;
>>> +       int ret;
>>> +
>>> +       /*
>>> +        * The vma->pages are only valid within the lifespan of the borrowed
>>> +        * obj->mm.pages. When the obj->mm.pages sg_table is regenerated, so
>>> +        * must be the vma->pages. A simple rule is that vma->pages must only
>>> +        * be accessed when the obj->mm.pages are pinned.
>>> +        */
>>> +       GEM_BUG_ON(!i915_gem_object_has_pinned_pages(vma->obj));
>>> +
>>> +       switch (vma->ggtt_view.type) {
>>> +       default:
>>> +               GEM_BUG_ON(vma->ggtt_view.type);
>>> +               fallthrough;
>>> +       case I915_GGTT_VIEW_NORMAL:
>>> +               pages = vma->obj->mm.pages;
>>> +               break;
>>> +
>>> +       case I915_GGTT_VIEW_ROTATED:
>>> +               pages =
>>> +                       intel_rotate_pages(&vma->ggtt_view.rotated, vma->obj);
>>> +               break;
>>> +
>>> +       case I915_GGTT_VIEW_REMAPPED:
>>> +               pages =
>>> +                       intel_remap_pages(&vma->ggtt_view.remapped, vma->obj);
>>> +               break;
>>> +
>>> +       case I915_GGTT_VIEW_PARTIAL:
>>> +               pages = intel_partial_pages(&vma->ggtt_view, vma->obj);
>>> +               break;
>>> +       }
>>> +
>>> +       ret = 0;
>>> +       /* gen6 ppgtt doesn't have backing pages, special-case it */
>>> +       if (IS_ERR(pages) && pages != ERR_PTR(-ENODEV)) {
>> Where does this -ENODEV come from? AFAIK for the gen6 thing mm.pages =
>> ZERO_SIZE_PTR. Also, just checking, I assume we always hit the
>> VIEW_NORMAL for that?
It was from when I was still converting the code. Looks like it can be removed now because setting pages to -ENODEV caused too many changes, and be unconditional IS_ERR.
>>> +               ret = PTR_ERR(pages);
>>> +               pages = NULL;
>>> +               drm_err(&vma->vm->i915->drm,
>>> +                       "Failed to get pages for VMA view type %u (%d)!\n",
>>> +                       vma->ggtt_view.type, ret);
>> Can we just return here?
Yeah, should be harmless. Out of paranoia I set pages to 0 below.
>>> +       }
>>> +
>>> +       pages = xchg(&vma->pages, pages);
>>> +
>>> +       /* did we race against a put_pages? */
>>> +       if (pages && pages != vma->obj->mm.pages) {
>>> +               sg_free_table(vma->pages);
>>> +               kfree(vma->pages);
>>> +       }
>> What is this race exactly, can we add some more details here please?
>> So we can more easily evaluate the lockless trickery here.
> Ok, the lockless stuff just gets removed by the end of the series.

Correct!

Will fix the ENODEV thing and send a new version.

~Maarten




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