drm/panfrost: Add the panfrost_gem_mapping concept

With the introduction of per-FD address space, the same BO can be mapped
in different address space if the BO is globally visible (GEM_FLINK)
and opened in different context or if the dmabuf is self-imported. The
current implementation does not take case into account, and attaches the
mapping directly to the panfrost_gem_object.

Let's create a panfrost_gem_mapping struct and allow multiple mappings
per BO.

The mappings are refcounted which helps solve another problem where
mappings were torn down (GEM handle closed by userspace) while GPU
jobs accessing those BOs were still in-flight. Jobs now keep a
reference on the mappings they use.

v2 (robh):
- Minor review comment clean-ups from Steven
- Use list_is_singular helper
- Just WARN if we add a mapping when madvise state is not WILLNEED.
  With that, drop the use of object_name_lock.

v3 (robh):
- Revert returning list iterator in panfrost_gem_mapping_get()

Fixes: a5efb4c9a562 ("drm/panfrost: Restructure the GEM object creation")
Fixes: 7282f7645d06 ("drm/panfrost: Implement per FD address spaces")
Cc: <stable@vger.kernel.org>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200116021554.15090-1-robh@kernel.org

1 files changed, 35 insertions, 26 deletions

diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c
index a3ed64a1f15e..763cfca886a7 100644
--- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
@@ -269,14 +269,15 @@ static int mmu_map_sg(struct panfrost_device *pfdev, struct panfrost_mmu *mmu,
 	return 0;
 }
 
-int panfrost_mmu_map(struct panfrost_gem_object *bo)
+int panfrost_mmu_map(struct panfrost_gem_mapping *mapping)
 {
+	struct panfrost_gem_object *bo = mapping->obj;
 	struct drm_gem_object *obj = &bo->base.base;
 	struct panfrost_device *pfdev = to_panfrost_device(obj->dev);
 	struct sg_table *sgt;
 	int prot = IOMMU_READ | IOMMU_WRITE;
 
-	if (WARN_ON(bo->is_mapped))
+	if (WARN_ON(mapping->active))
 		return 0;
 
 	if (bo->noexec)
@@ -286,25 +287,28 @@ int panfrost_mmu_map(struct panfrost_gem_object *bo)
 	if (WARN_ON(IS_ERR(sgt)))
 		return PTR_ERR(sgt);
 
-	mmu_map_sg(pfdev, bo->mmu, bo->node.start << PAGE_SHIFT, prot, sgt);
-	bo->is_mapped = true;
+	mmu_map_sg(pfdev, mapping->mmu, mapping->mmnode.start << PAGE_SHIFT,
+		   prot, sgt);
+	mapping->active = true;
 
 	return 0;
 }
 
-void panfrost_mmu_unmap(struct panfrost_gem_object *bo)
+void panfrost_mmu_unmap(struct panfrost_gem_mapping *mapping)
 {
+	struct panfrost_gem_object *bo = mapping->obj;
 	struct drm_gem_object *obj = &bo->base.base;
 	struct panfrost_device *pfdev = to_panfrost_device(obj->dev);
-	struct io_pgtable_ops *ops = bo->mmu->pgtbl_ops;
-	u64 iova = bo->node.start << PAGE_SHIFT;
-	size_t len = bo->node.size << PAGE_SHIFT;
+	struct io_pgtable_ops *ops = mapping->mmu->pgtbl_ops;
+	u64 iova = mapping->mmnode.start << PAGE_SHIFT;
+	size_t len = mapping->mmnode.size << PAGE_SHIFT;
 	size_t unmapped_len = 0;
 
-	if (WARN_ON(!bo->is_mapped))
+	if (WARN_ON(!mapping->active))
 		return;
 
-	dev_dbg(pfdev->dev, "unmap: as=%d, iova=%llx, len=%zx", bo->mmu->as, iova, len);
+	dev_dbg(pfdev->dev, "unmap: as=%d, iova=%llx, len=%zx",
+		mapping->mmu->as, iova, len);
 
 	while (unmapped_len < len) {
 		size_t unmapped_page;
@@ -318,8 +322,9 @@ void panfrost_mmu_unmap(struct panfrost_gem_object *bo)
 		unmapped_len += pgsize;
 	}
 
-	panfrost_mmu_flush_range(pfdev, bo->mmu, bo->node.start << PAGE_SHIFT, len);
-	bo->is_mapped = false;
+	panfrost_mmu_flush_range(pfdev, mapping->mmu,
+				 mapping->mmnode.start << PAGE_SHIFT, len);
+	mapping->active = false;
 }
 
 static void mmu_tlb_inv_context_s1(void *cookie)
@@ -394,10 +399,10 @@ void panfrost_mmu_pgtable_free(struct panfrost_file_priv *priv)
 	free_io_pgtable_ops(mmu->pgtbl_ops);
 }
 
-static struct panfrost_gem_object *
-addr_to_drm_mm_node(struct panfrost_device *pfdev, int as, u64 addr)
+static struct panfrost_gem_mapping *
+addr_to_mapping(struct panfrost_device *pfdev, int as, u64 addr)
 {
-	struct panfrost_gem_object *bo = NULL;
+	struct panfrost_gem_mapping *mapping = NULL;
 	struct panfrost_file_priv *priv;
 	struct drm_mm_node *node;
 	u64 offset = addr >> PAGE_SHIFT;
@@ -418,8 +423,9 @@ found_mmu:
 	drm_mm_for_each_node(node, &priv->mm) {
 		if (offset >= node->start &&
 		    offset < (node->start + node->size)) {
-			bo = drm_mm_node_to_panfrost_bo(node);
-			drm_gem_object_get(&bo->base.base);
+			mapping = drm_mm_node_to_panfrost_mapping(node);
+
+			kref_get(&mapping->refcount);
 			break;
 		}
 	}
@@ -427,7 +433,7 @@ found_mmu:
 	spin_unlock(&priv->mm_lock);
 out:
 	spin_unlock(&pfdev->as_lock);
-	return bo;
+	return mapping;
 }
 
 #define NUM_FAULT_PAGES (SZ_2M / PAGE_SIZE)
@@ -436,28 +442,30 @@ static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as,
 				       u64 addr)
 {
 	int ret, i;
+	struct panfrost_gem_mapping *bomapping;
 	struct panfrost_gem_object *bo;
 	struct address_space *mapping;
 	pgoff_t page_offset;
 	struct sg_table *sgt;
 	struct page **pages;
 
-	bo = addr_to_drm_mm_node(pfdev, as, addr);
-	if (!bo)
+	bomapping = addr_to_mapping(pfdev, as, addr);
+	if (!bomapping)
 		return -ENOENT;
 
+	bo = bomapping->obj;
 	if (!bo->is_heap) {
 		dev_WARN(pfdev->dev, "matching BO is not heap type (GPU VA = %llx)",
-			 bo->node.start << PAGE_SHIFT);
+			 bomapping->mmnode.start << PAGE_SHIFT);
 		ret = -EINVAL;
 		goto err_bo;
 	}
-	WARN_ON(bo->mmu->as != as);
+	WARN_ON(bomapping->mmu->as != as);
 
 	/* Assume 2MB alignment and size multiple */
 	addr &= ~((u64)SZ_2M - 1);
 	page_offset = addr >> PAGE_SHIFT;
-	page_offset -= bo->node.start;
+	page_offset -= bomapping->mmnode.start;
 
 	mutex_lock(&bo->base.pages_lock);
 
@@ -509,13 +517,14 @@ static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as,
 		goto err_map;
 	}
 
-	mmu_map_sg(pfdev, bo->mmu, addr, IOMMU_WRITE | IOMMU_READ | IOMMU_NOEXEC, sgt);
+	mmu_map_sg(pfdev, bomapping->mmu, addr,
+		   IOMMU_WRITE | IOMMU_READ | IOMMU_NOEXEC, sgt);
 
-	bo->is_mapped = true;
+	bomapping->active = true;
 
 	dev_dbg(pfdev->dev, "mapped page fault @ AS%d %llx", as, addr);
 
-	drm_gem_object_put_unlocked(&bo->base.base);
+	panfrost_gem_mapping_put(bomapping);
 
 	return 0;