[PATCH 4/4] diff

[Matthew Auld]

---
 drivers/gpu/drm/i915/gem/i915_gem_ttm.c      | 21 ++++++-
 drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c | 58 +++++++++++++++++---
 2 files changed, 70 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
index a81063e5aa93..052fa96d459e 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
@@ -1000,7 +1000,26 @@ static vm_fault_t vm_fault_ttm(struct vm_fault *vmf)
 		return VM_FAULT_SIGBUS;
 	}
 
-	if (!i915_ttm_resource_mappable(bo->resource)) {
+	/*
+	 * This must be swapped out with shmem ttm_tt (pipeline-gutting).
+	 * Calling ttm_bo_validate() here with TTM_PL_SYSTEM should only go as
+	 * far as far doing a ttm_bo_move_null(), which should skip all the
+	 * other junk.
+	 */
+	if (!bo->resource) {
+		struct ttm_operation_ctx ctx = {
+			.interruptible = true,
+			.no_wait_gpu = true, /* should be idle already */
+		};
+
+		GEM_BUG_ON(!bo->ttm || !(bo->ttm->page_flags & TTM_TT_FLAG_SWAPPED));
+
+		ret = ttm_bo_validate(bo, i915_ttm_sys_placement(), &ctx);
+		if (ret) {
+			dma_resv_unlock(bo->base.resv);
+			return VM_FAULT_SIGBUS;
+		}
+	} else if (!i915_ttm_resource_mappable(bo->resource)) {
 		int err = -ENODEV;
 		int i;
 
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
index c420d1ab605b..1bca67cfb0fa 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
@@ -103,7 +103,27 @@ void i915_ttm_adjust_gem_after_move(struct drm_i915_gem_object *obj)
 {
 	struct ttm_buffer_object *bo = i915_gem_to_ttm(obj);
 	unsigned int cache_level;
+	unsigned int mem_flags;
 	unsigned int i;
+	int mem_type;
+
+	/*
+	 * We might have been purged (or swapped out) if the resource is NULL,
+	 * in which case the SYSTEM placement is the closest match to describe
+	 * the current domain. If the object is ever used in this state then we
+	 * will require moving it again.
+	 */
+	if (!bo->resource) {
+		mem_flags = I915_BO_FLAG_STRUCT_PAGE;
+		mem_type = I915_PL_SYSTEM;
+		cache_level = I915_CACHE_NONE;
+	} else {
+		mem_flags = i915_ttm_cpu_maps_iomem(bo->resource) ? I915_BO_FLAG_IOMEM :
+			I915_BO_FLAG_STRUCT_PAGE;
+		mem_type = bo->resource->mem_type;
+		cache_level = i915_ttm_cache_level(to_i915(bo->base.dev), bo->resource,
+						   bo->ttm);
+	}
 
 	/*
 	 * If object was moved to an allowable region, update the object
@@ -111,11 +131,11 @@ void i915_ttm_adjust_gem_after_move(struct drm_i915_gem_object *obj)
 	 * in an allowable region, it's evicted and we don't update the
 	 * object region.
 	 */
-	if (intel_region_to_ttm_type(obj->mm.region) != bo->resource->mem_type) {
+	if (intel_region_to_ttm_type(obj->mm.region) != mem_type) {
 		for (i = 0; i < obj->mm.n_placements; ++i) {
 			struct intel_memory_region *mr = obj->mm.placements[i];
 
-			if (intel_region_to_ttm_type(mr) == bo->resource->mem_type &&
+			if (intel_region_to_ttm_type(mr) == mem_type &&
 			    mr != obj->mm.region) {
 				i915_gem_object_release_memory_region(obj);
 				i915_gem_object_init_memory_region(obj, mr);
@@ -125,12 +145,8 @@ void i915_ttm_adjust_gem_after_move(struct drm_i915_gem_object *obj)
 	}
 
 	obj->mem_flags &= ~(I915_BO_FLAG_STRUCT_PAGE | I915_BO_FLAG_IOMEM);
+	obj->mem_flags |= mem_flags;
 
-	obj->mem_flags |= i915_ttm_cpu_maps_iomem(bo->resource) ? I915_BO_FLAG_IOMEM :
-		I915_BO_FLAG_STRUCT_PAGE;
-
-	cache_level = i915_ttm_cache_level(to_i915(bo->base.dev), bo->resource,
-					   bo->ttm);
 	i915_gem_object_set_cache_coherency(obj, cache_level);
 }
 
@@ -560,7 +576,33 @@ int i915_ttm_move(struct ttm_buffer_object *bo, bool evict,
 	bool clear;
 	int ret;
 
-	if (GEM_WARN_ON(!obj) || !bo->resource) {
+	if (!bo->resource) {
+		if (GEM_WARN_ON(!obj)) {
+			ttm_bo_move_null(bo, dst_mem);
+			return 0;
+		}
+
+		if (dst_mem->mem_type != TTM_PL_SYSTEM) {
+			hop->mem_type = TTM_PL_SYSTEM;
+			hop->flags = TTM_PL_FLAG_TEMPORARY;
+			return -EMULTIHOP;
+		}
+
+		/*
+		 * This is only reached when first creating the object, or if
+		 * the object was purged or swapped out (pipeline-gutting). For
+		 * the former we can safely skip all of the below since we are
+		 * only using a dummy SYSTEM placement here. And with the latter
+		 * we will always re-enter here with bo->resource set correctly
+		 * (as per the above), since this is part of a multi-hop
+		 * sequence, where at the end we can do the move for real.
+		 *
+		 * The special case here is when the dst_mem is TTM_PL_SYSTEM,
+		 * which doens't require any kind of move, so it should be safe
+		 * to skip all the below and call ttm_bo_move_null() here, where
+		 * the caller in __i915_ttm_get_pages() will take care of the
+		 * rest, since we should have a valid ttm_tt.
+		 */
 		ttm_bo_move_null(bo, dst_mem);
 		return 0;
 	}
-- 
2.37.2