Merge branch 'etnaviv/next' of https://git.pengutronix.de/git/lst/linux into drm-next

fix address space collisions in some edge cases when userspace is
using softpin and cleans up the MMU reference handling a bit.
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Lucas Stach <l.stach@pengutronix.de>
Link: https://patchwork.freedesktop.org/patch/msgid/ffae9f7d03ca7a9e00da16d5910ae810befd3c5a.camel@pengutronix.de

drivers/gpu/drm/etnaviv/etnaviv_gem.c

@@ -294,18 +294,15 @@ struct etnaviv_vram_mapping *etnaviv_gem_mapping_get(
 		list_del(&mapping->obj_node);
 	}
 
-	mapping->context = etnaviv_iommu_context_get(mmu_context);
 	mapping->use = 1;
 
 	ret = etnaviv_iommu_map_gem(mmu_context, etnaviv_obj,
 				    mmu_context->global->memory_base,
 				    mapping, va);
-	if (ret < 0) {
-		etnaviv_iommu_context_put(mmu_context);
+	if (ret < 0)
 		kfree(mapping);
-	} else {
+	else
 		list_add_tail(&mapping->obj_node, &etnaviv_obj->vram_list);
-	}
 
 out:
 	mutex_unlock(&etnaviv_obj->lock);
@@ -500,10 +497,8 @@ void etnaviv_gem_free_object(struct drm_gem_object *obj)
 
 		WARN_ON(mapping->use);
 
-		if (context) {
+		if (context)
 			etnaviv_iommu_unmap_gem(context, mapping);
-			etnaviv_iommu_context_put(context);
-		}
 
 		list_del(&mapping->obj_node);
 		kfree(mapping);

drivers/gpu/drm/etnaviv/etnaviv_mmu.c

@@ -92,6 +92,8 @@ static int etnaviv_iommu_map(struct etnaviv_iommu_context *context, u32 iova,
 		da += bytes;
 	}
 
+	context->flush_seq++;
+
 	return 0;
 
 fail:
@@ -117,6 +119,8 @@ static void etnaviv_iommu_unmap(struct etnaviv_iommu_context *context, u32 iova,
 
 		da += bytes;
 	}
+
+	context->flush_seq++;
 }
 
 static void etnaviv_iommu_remove_mapping(struct etnaviv_iommu_context *context,
@@ -219,8 +223,47 @@ static int etnaviv_iommu_find_iova(struct etnaviv_iommu_context *context,
 static int etnaviv_iommu_insert_exact(struct etnaviv_iommu_context *context,
 		   struct drm_mm_node *node, size_t size, u64 va)
 {
+	struct etnaviv_vram_mapping *m, *n;
+	struct drm_mm_node *scan_node;
+	LIST_HEAD(scan_list);
+	int ret;
+
 	lockdep_assert_held(&context->lock);
 
+	ret = drm_mm_insert_node_in_range(&context->mm, node, size, 0, 0, va,
+					  va + size, DRM_MM_INSERT_LOWEST);
+	if (ret != -ENOSPC)
+		return ret;
+
+	/*
+	 * When we can't insert the node, due to a existing mapping blocking
+	 * the address space, there are two possible reasons:
+	 * 1. Userspace genuinely messed up and tried to reuse address space
+	 * before the last job using this VMA has finished executing.
+	 * 2. The existing buffer mappings are idle, but the buffers are not
+	 * destroyed yet (likely due to being referenced by another context) in
+	 * which case the mappings will not be cleaned up and we must reap them
+	 * here to make space for the new mapping.
+	 */
+
+	drm_mm_for_each_node_in_range(scan_node, &context->mm, va, va + size) {
+		m = container_of(scan_node, struct etnaviv_vram_mapping,
+				 vram_node);
+
+		if (m->use)
+			return -ENOSPC;
+
+		list_add(&m->scan_node, &scan_list);
+	}
+
+	list_for_each_entry_safe(m, n, &scan_list, scan_node) {
+		etnaviv_iommu_remove_mapping(context, m);
+		etnaviv_iommu_context_put(m->context);
+		m->context = NULL;
+		list_del_init(&m->mmu_node);
+		list_del_init(&m->scan_node);
+	}
+
 	return drm_mm_insert_node_in_range(&context->mm, node, size, 0, 0, va,
 					   va + size, DRM_MM_INSERT_LOWEST);
 }
@@ -245,6 +288,7 @@ int etnaviv_iommu_map_gem(struct etnaviv_iommu_context *context,
 		iova = sg_dma_address(sgt->sgl) - memory_base;
 		if (iova < 0x80000000 - sg_dma_len(sgt->sgl)) {
 			mapping->iova = iova;
+			mapping->context = etnaviv_iommu_context_get(context);
 			list_add_tail(&mapping->mmu_node, &context->mappings);
 			ret = 0;
 			goto unlock;
@@ -271,8 +315,8 @@ int etnaviv_iommu_map_gem(struct etnaviv_iommu_context *context,
 		goto unlock;
 	}
 
+	mapping->context = etnaviv_iommu_context_get(context);
 	list_add_tail(&mapping->mmu_node, &context->mappings);
-	context->flush_seq++;
 unlock:
 	mutex_unlock(&context->lock);
 
@@ -286,13 +330,19 @@ void etnaviv_iommu_unmap_gem(struct etnaviv_iommu_context *context,
 
 	mutex_lock(&context->lock);
 
+	/* Bail if the mapping has been reaped by another thread */
+	if (!mapping->context) {
+		mutex_unlock(&context->lock);
+		return;
+	}
+
 	/* If the vram node is on the mm, unmap and remove the node */
 	if (mapping->vram_node.mm == &context->mm)
 		etnaviv_iommu_remove_mapping(context, mapping);
 
 	list_del(&mapping->mmu_node);
-	context->flush_seq++;
 	mutex_unlock(&context->lock);
+	etnaviv_iommu_context_put(context);
 }
 
 static void etnaviv_iommu_context_free(struct kref *kref)