On Thu, Oct 31, 2024 at 11:10:42AM -0700, Matthew Brost wrote:
> Non-contiguous VRAM cannot easily be mapped in TTM nor can non-visible
> VRAM easily be accessed. Add ttm_bo_access, which is similar to
> ttm_bo_vm_access, to access such memory.
>
> v4:
> - Fix checkpatch warnings (CI)
> v5:
> - Fix checkpatch warnings (CI)
> v6:
> - Fix kernel doc (Auld)
>
Christian - Do you mind if I merge patch along with the rest of the
series to drm-xe-next?
Matt
> Reported-by: Christoph Manszewski <christoph.manszewski@xxxxxxxxx>
> Suggested-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
> Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
> Tested-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
> Reviewed-by: Matthew Auld <matthew.auld@xxxxxxxxx>
> ---
> drivers/gpu/drm/ttm/ttm_bo_util.c | 86 +++++++++++++++++++++++++++++++
> drivers/gpu/drm/ttm/ttm_bo_vm.c | 65 +----------------------
> include/drm/ttm/ttm_bo.h | 2 +
> 3 files changed, 89 insertions(+), 64 deletions(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
> index d939925efa81..77e760ea7193 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_util.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
> @@ -919,3 +919,89 @@ s64 ttm_lru_walk_for_evict(struct ttm_lru_walk *walk, struct ttm_device *bdev,
>
> return progress;
> }
> +
> +static int ttm_bo_access_kmap(struct ttm_buffer_object *bo,
> + unsigned long offset,
> + void *buf, int len, int write)
> +{
> + unsigned long page = offset >> PAGE_SHIFT;
> + unsigned long bytes_left = len;
> + int ret;
> +
> + /* Copy a page at a time, that way no extra virtual address
> + * mapping is needed
> + */
> + offset -= page << PAGE_SHIFT;
> + do {
> + unsigned long bytes = min(bytes_left, PAGE_SIZE - offset);
> + struct ttm_bo_kmap_obj map;
> + void *ptr;
> + bool is_iomem;
> +
> + ret = ttm_bo_kmap(bo, page, 1, &map);
> + if (ret)
> + return ret;
> +
> + ptr = (void *)ttm_kmap_obj_virtual(&map, &is_iomem) + offset;
> + WARN_ON_ONCE(is_iomem);
> + if (write)
> + memcpy(ptr, buf, bytes);
> + else
> + memcpy(buf, ptr, bytes);
> + ttm_bo_kunmap(&map);
> +
> + page++;
> + buf += bytes;
> + bytes_left -= bytes;
> + offset = 0;
> + } while (bytes_left);
> +
> + return len;
> +}
> +
> +/**
> + * ttm_bo_access - Helper to access a buffer object
> + *
> + * @bo: ttm buffer object
> + * @offset: access offset into buffer object
> + * @buf: pointer to caller memory to read into or write from
> + * @len: length of access
> + * @write: write access
> + *
> + * Utility function to access a buffer object. Useful when buffer object cannot
> + * be easily mapped (non-contiguous, non-visible, etc...).
> + *
> + * Returns:
> + * @len if successful, negative error code on failure.
> + */
> +int ttm_bo_access(struct ttm_buffer_object *bo, unsigned long offset,
> + void *buf, int len, int write)
> +{
> + int ret;
> +
> + if (len < 1 || (offset + len) > bo->base.size)
> + return -EIO;
> +
> + ret = ttm_bo_reserve(bo, true, false, NULL);
> + if (ret)
> + return ret;
> +
> + switch (bo->resource->mem_type) {
> + case TTM_PL_SYSTEM:
> + fallthrough;
> + case TTM_PL_TT:
> + ret = ttm_bo_access_kmap(bo, offset, buf, len, write);
> + break;
> + default:
> + if (bo->bdev->funcs->access_memory)
> + ret = bo->bdev->funcs->access_memory
> + (bo, offset, buf, len, write);
> + else
> + ret = -EIO;
> + }
> +
> + ttm_bo_unreserve(bo);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL(ttm_bo_access);
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> index 2c699ed1963a..20b1e5f78684 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> @@ -366,45 +366,6 @@ void ttm_bo_vm_close(struct vm_area_struct *vma)
> }
> EXPORT_SYMBOL(ttm_bo_vm_close);
>
> -static int ttm_bo_vm_access_kmap(struct ttm_buffer_object *bo,
> - unsigned long offset,
> - uint8_t *buf, int len, int write)
> -{
> - unsigned long page = offset >> PAGE_SHIFT;
> - unsigned long bytes_left = len;
> - int ret;
> -
> - /* Copy a page at a time, that way no extra virtual address
> - * mapping is needed
> - */
> - offset -= page << PAGE_SHIFT;
> - do {
> - unsigned long bytes = min(bytes_left, PAGE_SIZE - offset);
> - struct ttm_bo_kmap_obj map;
> - void *ptr;
> - bool is_iomem;
> -
> - ret = ttm_bo_kmap(bo, page, 1, &map);
> - if (ret)
> - return ret;
> -
> - ptr = (uint8_t *)ttm_kmap_obj_virtual(&map, &is_iomem) + offset;
> - WARN_ON_ONCE(is_iomem);
> - if (write)
> - memcpy(ptr, buf, bytes);
> - else
> - memcpy(buf, ptr, bytes);
> - ttm_bo_kunmap(&map);
> -
> - page++;
> - buf += bytes;
> - bytes_left -= bytes;
> - offset = 0;
> - } while (bytes_left);
> -
> - return len;
> -}
> -
> int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
> void *buf, int len, int write)
> {
> @@ -412,32 +373,8 @@ int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
> unsigned long offset = (addr) - vma->vm_start +
> ((vma->vm_pgoff - drm_vma_node_start(&bo->base.vma_node))
> << PAGE_SHIFT);
> - int ret;
> -
> - if (len < 1 || (offset + len) > bo->base.size)
> - return -EIO;
>
> - ret = ttm_bo_reserve(bo, true, false, NULL);
> - if (ret)
> - return ret;
> -
> - switch (bo->resource->mem_type) {
> - case TTM_PL_SYSTEM:
> - fallthrough;
> - case TTM_PL_TT:
> - ret = ttm_bo_vm_access_kmap(bo, offset, buf, len, write);
> - break;
> - default:
> - if (bo->bdev->funcs->access_memory)
> - ret = bo->bdev->funcs->access_memory(
> - bo, offset, buf, len, write);
> - else
> - ret = -EIO;
> - }
> -
> - ttm_bo_unreserve(bo);
> -
> - return ret;
> + return ttm_bo_access(bo, offset, buf, len, write);
> }
> EXPORT_SYMBOL(ttm_bo_vm_access);
>
> diff --git a/include/drm/ttm/ttm_bo.h b/include/drm/ttm/ttm_bo.h
> index 5804408815be..8ea11cd8df39 100644
> --- a/include/drm/ttm/ttm_bo.h
> +++ b/include/drm/ttm/ttm_bo.h
> @@ -421,6 +421,8 @@ void ttm_bo_unpin(struct ttm_buffer_object *bo);
> int ttm_bo_evict_first(struct ttm_device *bdev,
> struct ttm_resource_manager *man,
> struct ttm_operation_ctx *ctx);
> +int ttm_bo_access(struct ttm_buffer_object *bo, unsigned long offset,
> + void *buf, int len, int write);
> vm_fault_t ttm_bo_vm_reserve(struct ttm_buffer_object *bo,
> struct vm_fault *vmf);
> vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
> --
> 2.34.1
>
