Re: [Intel-gfx] [PATCH v10 03/11] drm/ttm: Add a generic TTM memcpy move for page-based iomem

[Christian König <christian.koenig@xxxxxxx>]

Am 30.08.21 um 03:54 schrieb Dave Airlie:
> I've just been talking with Ben about nouveau having some issues since
> this path,
>
> ttm_resource can be subclassed by drivers, and the code below that
> copies ttm_resources around pretty much seems to destroy that.
>
>
> > +       struct ttm_resource *src_mem = &bo->mem;
> > +       struct ttm_resource_manager *src_man =
> > +               ttm_manager_type(bdev, src_mem->mem_type);
> > +       struct ttm_resource src_copy = *src_mem;
> This here ^^

Mhm, that's most likely a rebase/merge conflict between my change to 
subclass ttm_resource which came in through the drm-misc-next tree and 
Thomas change here.

Thomas can you take a look?

Thanks,
Christian.

> > +       union {
> > +               struct ttm_kmap_iter_tt tt;
> > +               struct ttm_kmap_iter_linear_io io;
> > +       } _dst_iter, _src_iter;
> > +       struct ttm_kmap_iter *dst_iter, *src_iter;
> > +       int ret = 0;
> >
> > -       /*
> > -        * TTM might be null for moves within the same region.
> > -        */
> > -       if (ttm) {
> > +       if (ttm && ((ttm->page_flags & TTM_PAGE_FLAG_SWAPPED) ||
> > +                   dst_man->use_tt)) {
> >                  ret = ttm_tt_populate(bdev, ttm, ctx);
> >                  if (ret)
> > -                       goto out1;
> > +                       return ret;
> >          }
> >
> > -       for (i = 0; i < new_mem->num_pages; ++i) {
> > -               if (old_iomap == NULL) {
> > -                       pgprot_t prot = ttm_io_prot(bo, old_mem, PAGE_KERNEL);
> > -                       ret = ttm_copy_ttm_io_page(ttm, new_iomap, i,
> > -                                                  prot);
> > -               } else if (new_iomap == NULL) {
> > -                       pgprot_t prot = ttm_io_prot(bo, new_mem, PAGE_KERNEL);
> > -                       ret = ttm_copy_io_ttm_page(ttm, old_iomap, i,
> > -                                                  prot);
> > -               } else {
> > -                       ret = ttm_copy_io_page(new_iomap, old_iomap, i);
> > -               }
> > -               if (ret)
> > -                       goto out1;
> > +       dst_iter = ttm_kmap_iter_linear_io_init(&_dst_iter.io, bdev, dst_mem);
> > +       if (PTR_ERR(dst_iter) == -EINVAL && dst_man->use_tt)
> > +               dst_iter = ttm_kmap_iter_tt_init(&_dst_iter.tt, bo->ttm);
> > +       if (IS_ERR(dst_iter))
> > +               return PTR_ERR(dst_iter);
> > +
> > +       src_iter = ttm_kmap_iter_linear_io_init(&_src_iter.io, bdev, src_mem);
> > +       if (PTR_ERR(src_iter) == -EINVAL && src_man->use_tt)
> > +               src_iter = ttm_kmap_iter_tt_init(&_src_iter.tt, bo->ttm);
> > +       if (IS_ERR(src_iter)) {
> > +               ret = PTR_ERR(src_iter);
> > +               goto out_src_iter;
> >          }
> > -       mb();
> > -out2:
> > -       old_copy = *old_mem;
> >
> > -       ttm_bo_assign_mem(bo, new_mem);
> > -
> > -       if (!man->use_tt)
> > -               ttm_bo_tt_destroy(bo);
> > +       ttm_move_memcpy(bo, dst_mem->num_pages, dst_iter, src_iter);
> > +       src_copy = *src_mem;
> > +       ttm_bo_move_sync_cleanup(bo, dst_mem);
> >
> > -out1:
> > -       ttm_resource_iounmap(bdev, old_mem, new_iomap);
> > -out:
> > -       ttm_resource_iounmap(bdev, &old_copy, old_iomap);
> > +       if (!src_iter->ops->maps_tt)
> > +               ttm_kmap_iter_linear_io_fini(&_src_iter.io, bdev, &src_copy);
> passes a copy into linear_io_fini which calls the driver io_mem_free
> without the subclass data.
>
> Dave.