[PATCH v3 7/8] drm/panfrost: Implement generic DRM object RSS reporting function

[Adrián Larumbe <adrian.larumbe@xxxxxxxxxxxxx>]

BO's RSS is updated every time new pages are allocated on demand and mapped
for the object at GPU page fault's IRQ handler, but only for heap buffers.
The reason this is unnecessary for non-heap buffers is that they are mapped
onto the GPU's VA space and backed by physical memory in their entirety at
BO creation time.

This calculation is unnecessary for imported PRIME objects, since heap
buffers cannot be exported by our driver, and the actual BO RSS size is the
one reported in its attached dmabuf structure.

Signed-off-by: Adrián Larumbe <adrian.larumbe@xxxxxxxxxxxxx>
---
 drivers/gpu/drm/panfrost/panfrost_gem.c | 14 ++++++++++++++
 drivers/gpu/drm/panfrost/panfrost_gem.h |  5 +++++
 drivers/gpu/drm/panfrost/panfrost_mmu.c | 12 ++++++++----
 3 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c
index 7d8f83d20539..cb92c0ed7615 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gem.c
+++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
@@ -208,6 +208,19 @@ static enum drm_gem_object_status panfrost_gem_status(struct drm_gem_object *obj
 	return res;
 }
 
+static size_t panfrost_gem_rss(struct drm_gem_object *obj)
+{
+	struct panfrost_gem_object *bo = to_panfrost_bo(obj);
+
+	if (bo->is_heap)
+		return bo->heap_rss_size;
+	else if (bo->base.pages) {
+		WARN_ON(bo->heap_rss_size);
+		return bo->base.base.size;
+	} else
+		return 0;
+}
+
 static const struct drm_gem_object_funcs panfrost_gem_funcs = {
 	.free = panfrost_gem_free_object,
 	.open = panfrost_gem_open,
@@ -220,6 +233,7 @@ static const struct drm_gem_object_funcs panfrost_gem_funcs = {
 	.vunmap = drm_gem_shmem_object_vunmap,
 	.mmap = drm_gem_shmem_object_mmap,
 	.status = panfrost_gem_status,
+	.rss = panfrost_gem_rss,
 	.vm_ops = &drm_gem_shmem_vm_ops,
 };
 
diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.h b/drivers/gpu/drm/panfrost/panfrost_gem.h
index ad2877eeeccd..13c0a8149c3a 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gem.h
+++ b/drivers/gpu/drm/panfrost/panfrost_gem.h
@@ -36,6 +36,11 @@ struct panfrost_gem_object {
 	 */
 	atomic_t gpu_usecount;
 
+	/*
+	 * Object chunk size currently mapped onto physical memory
+	 */
+	size_t heap_rss_size;
+
 	bool noexec		:1;
 	bool is_heap		:1;
 };
diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c
index d54d4e7b2195..67c206124781 100644
--- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
@@ -285,17 +285,19 @@ static void panfrost_mmu_flush_range(struct panfrost_device *pfdev,
 	pm_runtime_put_autosuspend(pfdev->dev);
 }
 
-static int mmu_map_sg(struct panfrost_device *pfdev, struct panfrost_mmu *mmu,
+static size_t mmu_map_sg(struct panfrost_device *pfdev, struct panfrost_mmu *mmu,
 		      u64 iova, int prot, struct sg_table *sgt)
 {
 	unsigned int count;
 	struct scatterlist *sgl;
 	struct io_pgtable_ops *ops = mmu->pgtbl_ops;
 	u64 start_iova = iova;
+	size_t total = 0;
 
 	for_each_sgtable_dma_sg(sgt, sgl, count) {
 		unsigned long paddr = sg_dma_address(sgl);
 		size_t len = sg_dma_len(sgl);
+		total += len;
 
 		dev_dbg(pfdev->dev, "map: as=%d, iova=%llx, paddr=%lx, len=%zx", mmu->as, iova, paddr, len);
 
@@ -315,7 +317,7 @@ static int mmu_map_sg(struct panfrost_device *pfdev, struct panfrost_mmu *mmu,
 
 	panfrost_mmu_flush_range(pfdev, mmu, start_iova, iova - start_iova);
 
-	return 0;
+	return total;
 }
 
 int panfrost_mmu_map(struct panfrost_gem_mapping *mapping)
@@ -447,6 +449,7 @@ static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as,
 	pgoff_t page_offset;
 	struct sg_table *sgt;
 	struct page **pages;
+	size_t mapped_size;
 
 	bomapping = addr_to_mapping(pfdev, as, addr);
 	if (!bomapping)
@@ -518,10 +521,11 @@ static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as,
 	if (ret)
 		goto err_map;
 
-	mmu_map_sg(pfdev, bomapping->mmu, addr,
-		   IOMMU_WRITE | IOMMU_READ | IOMMU_NOEXEC, sgt);
+	mapped_size = mmu_map_sg(pfdev, bomapping->mmu, addr,
+				 IOMMU_WRITE | IOMMU_READ | IOMMU_NOEXEC, sgt);
 
 	bomapping->active = true;
+	bo->heap_rss_size += mapped_size;
 
 	dev_dbg(pfdev->dev, "mapped page fault @ AS%d %llx", as, addr);
 
-- 
2.42.0