drm/ttm: Add an allocation flag to propagate -ENOSPC on OOM

Some graphics APIs differentiate between out-of-graphics-memory and
out-of-host-memory (system memory). Add a device init flag to have -ENOSPC
propagated from the resource managers instead of being converted to
-ENOMEM, to aid driver stacks in determining what error code to return or
whether corrective action can be taken at the driver level.

Co-developed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Tvrtko Ursulin <tursulin@ursulin.net>
Link: https://lore.kernel.org/r/20251020115411.36818-7-tvrtko.ursulin@igalia.com

drivers/gpu/drm/ttm/ttm_bo.c

@@ -32,6 +32,7 @@
 #define pr_fmt(fmt) "[TTM] " fmt
 
 #include <drm/drm_print.h>
+#include <drm/ttm/ttm_allocation.h>
 #include <drm/ttm/ttm_bo.h>
 #include <drm/ttm/ttm_placement.h>
 #include <drm/ttm/ttm_tt.h>
@@ -878,7 +879,8 @@ bounce:
 
 	/* For backward compatibility with userspace */
 	if (ret == -ENOSPC)
-		return -ENOMEM;
+		return bo->bdev->alloc_flags & TTM_ALLOCATION_PROPAGATE_ENOSPC ?
+		       ret : -ENOMEM;
 
 	/*
 	 * We might need to add a TTM.

drivers/gpu/drm/ttm/ttm_device.c

@@ -227,6 +227,7 @@ int ttm_device_init(struct ttm_device *bdev, const struct ttm_device_funcs *func
 		return -ENOMEM;
 	}
 
+	bdev->alloc_flags = alloc_flags;
 	bdev->funcs = funcs;
 
 	ttm_sys_man_init(bdev);

include/drm/ttm/ttm_allocation.h

@@ -7,5 +7,6 @@
 #define TTM_ALLOCATION_POOL_BENEFICIAL_ORDER(n)	((n) & 0xff) /* Max order which caller can benefit from */
 #define TTM_ALLOCATION_POOL_USE_DMA_ALLOC 	BIT(8) /* Use coherent DMA allocations. */
 #define TTM_ALLOCATION_POOL_USE_DMA32		BIT(9) /* Use GFP_DMA32 allocations. */
+#define TTM_ALLOCATION_PROPAGATE_ENOSPC		BIT(10) /* Do not convert ENOSPC from resource managers to ENOMEM. */
 
 #endif

include/drm/ttm/ttm_device.h

@@ -220,6 +220,11 @@ struct ttm_device {
 	 */
 	struct list_head device_list;
 
+	/**
+	 * @alloc_flags: TTM_ALLOCATION_ flags.
+	 */
+	unsigned int alloc_flags;
+
 	/**
 	 * @funcs: Function table for the device.
 	 * Constant after bo device init