On Mon, Nov 04, 2024 at 08:28:34PM +0100, Christian König wrote:Am 04.11.24 um 18:34 schrieb Rodrigo Vivi:On Thu, Oct 31, 2024 at 04:43:19PM -0700, Matthew Brost wrote: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?Ray, Christian, ack on getting this patch to drm-xe-next?No, we actually spend quite some time removing the single page mapping functionality for BOs.I don't understand this statement. This patch just adds a TTM BO helper for access - it doesn't change anything wrt to single page mapping.
Well we spend quite some time removing single page mappings from device drivers.
The only remaining use case of ttm_bo_kmap() with just one page is the ttm_bo_vm_access_kmap() function and I was really hoping to make that one TTM internal at some point.
You need a really good justification to bring that back.The use case is EuDebugger requires essentially the same functionality as ptrace -> vm_access.
Then why don't you use ptrace in the first place?
TTM mapping non-contiguous VRAM doesn't work unless I'm blind. User BOs which the EuDebugger accesses can be non-contiguous, hence the new helper.
Then why don't you handle that inside the driver in the first place instead of going through a TTM midlayer?
Regards,
Christian.
MattRegards, Christian.MattReported-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
