It looks like we need this for local-memory, if we want to use ptrace. Something more is still needed if we want to handle non-mappable memory, which looks quite annoying. References: https://gitlab.freedesktop.org/drm/intel/-/issues/6989 Signed-off-by: Matthew Auld <matthew.auld@xxxxxxxxx> Cc: Nirmoy Das <nirmoy.das@xxxxxxxxx> --- drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 43 +++++++++++++++++++++++++ 1 file changed, 43 insertions(+) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c index 3dc6acfcf4ec..4f533e0c92b4 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c @@ -699,6 +699,48 @@ static unsigned long i915_ttm_io_mem_pfn(struct ttm_buffer_object *bo, return ((base + sg_dma_address(sg)) >> PAGE_SHIFT) + ofs; } +static int i915_ttm_access_memory(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; + + /* + * TODO: For now just let it fail if the resource is non-mappable, + * otherwise we need to perform the memcpy from the gpu here, without + * interfering with the object (like moving the entire thing). + */ + + offset -= page << PAGE_SHIFT; + do { + unsigned long bytes = min(bytes_left, PAGE_SIZE - offset); + struct ttm_bo_kmap_obj map; + void __iomem *ptr; + bool is_iomem; + + ret = ttm_bo_kmap(bo, page, 1, &map); + if (ret) + return ret; + + ptr = ttm_kmap_obj_virtual(&map, &is_iomem) + offset; + WARN_ON_ONCE(!is_iomem); + if (write) + memcpy_toio(ptr, buf, bytes); + else + memcpy_fromio(buf, ptr, bytes); + ttm_bo_kunmap(&map); + + page++; + buf += bytes; + bytes_left -= bytes; + offset = 0; + } while (bytes_left); + + return len; +} + /* * All callbacks need to take care not to downcast a struct ttm_buffer_object * without checking its subclass, since it might be a TTM ghost object. @@ -715,6 +757,7 @@ static struct ttm_device_funcs i915_ttm_bo_driver = { .delete_mem_notify = i915_ttm_delete_mem_notify, .io_mem_reserve = i915_ttm_io_mem_reserve, .io_mem_pfn = i915_ttm_io_mem_pfn, + .access_memory = i915_ttm_access_memory, }; /** -- 2.37.3
