On Tue, Feb 27, 2018 at 01:07:06PM +0100, Christian König wrote: > Hi guys, > > at least on amdgpu and radeon the page array allocated by ttm_dma_tt_init is > completely unused in the case of DMA-buf sharing. So I'm trying to get rid > of that by only allocating the DMA address array. > > Now the only other user of DMA-buf together with ttm_dma_tt_init is Nouveau. > So my question is are you guys using the page array anywhere in your kernel > driver in case of a DMA-buf sharing? > > If no then I could just make this the default behavior for all drivers and > save quite a bit of memory for everybody.
+1 on teaching ttm to no longer look at the struct page * in the dma-buf sgt, but only the dma_buf address. If there's still some need for in-kernel cpu or userspace mmap access then imo ttm needs to be fixed to delegate all that to the right dma-buf interfaces. The ttm abstraction is already there, it's just not passed through. I don't pretend to now enough of the details to review this stuff :-) -Daniel > > Thanks, > Christian. > > Am 27.02.2018 um 12:49 schrieb Christian König: > > This allows drivers to only allocate dma addresses, but not a page > > array. > > > > Signed-off-by: Christian König <christian.koe...@amd.com> > > --- > > drivers/gpu/drm/ttm/ttm_tt.c | 54 > > ++++++++++++++++++++++++++++++++++++-------- > > include/drm/ttm/ttm_tt.h | 2 ++ > > 2 files changed, 47 insertions(+), 9 deletions(-) > > > > diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c > > index 8e0b525cda00..971133106ec2 100644 > > --- a/drivers/gpu/drm/ttm/ttm_tt.c > > +++ b/drivers/gpu/drm/ttm/ttm_tt.c > > @@ -108,6 +108,16 @@ static int ttm_dma_tt_alloc_page_directory(struct > > ttm_dma_tt *ttm) > > return 0; > > } > > +static int ttm_sg_tt_alloc_page_directory(struct ttm_dma_tt *ttm) > > +{ > > + ttm->dma_address = kvmalloc_array(ttm->ttm.num_pages, > > + sizeof(*ttm->dma_address), > > + GFP_KERNEL | __GFP_ZERO); > > + if (!ttm->dma_address) > > + return -ENOMEM; > > + return 0; > > +} > > + > > #ifdef CONFIG_X86 > > static inline int ttm_tt_set_page_caching(struct page *p, > > enum ttm_caching_state c_old, > > @@ -227,8 +237,8 @@ void ttm_tt_destroy(struct ttm_tt *ttm) > > ttm->func->destroy(ttm); > > } > > -int ttm_tt_init(struct ttm_tt *ttm, struct ttm_bo_device *bdev, > > - unsigned long size, uint32_t page_flags) > > +void ttm_tt_init_fields(struct ttm_tt *ttm, struct ttm_bo_device *bdev, > > + unsigned long size, uint32_t page_flags) > > { > > ttm->bdev = bdev; > > ttm->num_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; > > @@ -236,6 +246,12 @@ int ttm_tt_init(struct ttm_tt *ttm, struct > > ttm_bo_device *bdev, > > ttm->page_flags = page_flags; > > ttm->state = tt_unpopulated; > > ttm->swap_storage = NULL; > > +} > > + > > +int ttm_tt_init(struct ttm_tt *ttm, struct ttm_bo_device *bdev, > > + unsigned long size, uint32_t page_flags) > > +{ > > + ttm_tt_init_fields(ttm, bdev, size, page_flags); > > if (ttm_tt_alloc_page_directory(ttm)) { > > ttm_tt_destroy(ttm); > > @@ -258,12 +274,7 @@ int ttm_dma_tt_init(struct ttm_dma_tt *ttm_dma, struct > > ttm_bo_device *bdev, > > { > > struct ttm_tt *ttm = &ttm_dma->ttm; > > - ttm->bdev = bdev; > > - ttm->num_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; > > - ttm->caching_state = tt_cached; > > - ttm->page_flags = page_flags; > > - ttm->state = tt_unpopulated; > > - ttm->swap_storage = NULL; > > + ttm_tt_init_fields(ttm, bdev, size, page_flags); > > INIT_LIST_HEAD(&ttm_dma->pages_list); > > if (ttm_dma_tt_alloc_page_directory(ttm_dma)) { > > @@ -275,11 +286,36 @@ int ttm_dma_tt_init(struct ttm_dma_tt *ttm_dma, > > struct ttm_bo_device *bdev, > > } > > EXPORT_SYMBOL(ttm_dma_tt_init); > > +int ttm_sg_tt_init(struct ttm_dma_tt *ttm_dma, struct ttm_bo_device *bdev, > > + unsigned long size, uint32_t page_flags) > > +{ > > + struct ttm_tt *ttm = &ttm_dma->ttm; > > + int ret; > > + > > + ttm_tt_init_fields(ttm, bdev, size, page_flags); > > + > > + INIT_LIST_HEAD(&ttm_dma->pages_list); > > + if (page_flags & TTM_PAGE_FLAG_SG) > > + ret = ttm_sg_tt_alloc_page_directory(ttm_dma); > > + else > > + ret = ttm_dma_tt_alloc_page_directory(ttm_dma); > > + if (ret) { > > + ttm_tt_destroy(ttm); > > + pr_err("Failed allocating page table\n"); > > + return -ENOMEM; > > + } > > + return 0; > > +} > > +EXPORT_SYMBOL(ttm_sg_tt_init); > > + > > void ttm_dma_tt_fini(struct ttm_dma_tt *ttm_dma) > > { > > struct ttm_tt *ttm = &ttm_dma->ttm; > > - kvfree(ttm->pages); > > + if (ttm->pages) > > + kvfree(ttm->pages); > > + else > > + kvfree(ttm_dma->dma_address); > > ttm->pages = NULL; > > ttm_dma->dma_address = NULL; > > } > > diff --git a/include/drm/ttm/ttm_tt.h b/include/drm/ttm/ttm_tt.h > > index 9c78556b488e..1cf316a4257c 100644 > > --- a/include/drm/ttm/ttm_tt.h > > +++ b/include/drm/ttm/ttm_tt.h > > @@ -163,6 +163,8 @@ int ttm_tt_init(struct ttm_tt *ttm, struct > > ttm_bo_device *bdev, > > unsigned long size, uint32_t page_flags); > > int ttm_dma_tt_init(struct ttm_dma_tt *ttm_dma, struct ttm_bo_device > > *bdev, > > unsigned long size, uint32_t page_flags); > > +int ttm_sg_tt_init(struct ttm_dma_tt *ttm_dma, struct ttm_bo_device *bdev, > > + unsigned long size, uint32_t page_flags); > > /** > > * ttm_tt_fini > > _______________________________________________ > Nouveau mailing list > Nouveau@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/nouveau -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ Nouveau mailing list Nouveau@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/nouveau