drm/panfrost: Handle page mapping failure

When mapping the pages of a BO, either a heap type at page fault time or
else a non-heap BO at object creation time, if the ARM page table mapping
function fails, we unmap what had been mapped so far and bail out.

Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
Link: https://lore.kernel.org/r/20251019145225.3621989-7-adrian.larumbe@collabora.com
Signed-off-by: Steven Price <steven.price@arm.com>

Author: larunbe

drivers/gpu/drm/panfrost/panfrost_mmu.c

@@ -395,13 +395,32 @@ static void panfrost_mmu_flush_range(struct panfrost_device *pfdev,
 	pm_runtime_put_autosuspend(pfdev->base.dev);
 }
 
+static void mmu_unmap_range(struct panfrost_mmu *mmu, u64 iova, size_t len)
+{
+	struct io_pgtable_ops *ops = mmu->pgtbl_ops;
+	size_t pgsize, unmapped_len = 0;
+	size_t unmapped_page, pgcount;
+
+	while (unmapped_len < len) {
+		pgsize = get_pgsize(iova, len - unmapped_len, &pgcount);
+
+		unmapped_page = ops->unmap_pages(ops, iova, pgsize, pgcount, NULL);
+		WARN_ON(unmapped_page != pgsize * pgcount);
+
+		iova += pgsize * pgcount;
+		unmapped_len += pgsize * pgcount;
+	}
+}
+
 static int 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;
+	size_t total_mapped = 0;
 	u64 start_iova = iova;
+	int ret;
 
 	for_each_sgtable_dma_sg(sgt, sgl, count) {
 		unsigned long paddr = sg_dma_address(sgl);
@@ -415,10 +434,14 @@ static int mmu_map_sg(struct panfrost_device *pfdev, struct panfrost_mmu *mmu,
 			size_t pgcount, mapped = 0;
 			size_t pgsize = get_pgsize(iova | paddr, len, &pgcount);
 
-			ops->map_pages(ops, iova, paddr, pgsize, pgcount, prot,
+			ret = ops->map_pages(ops, iova, paddr, pgsize, pgcount, prot,
 				       GFP_KERNEL, &mapped);
+			if (ret)
+				goto err_unmap_pages;
+
 			/* Don't get stuck if things have gone wrong */
 			mapped = max(mapped, pgsize);
+			total_mapped += mapped;
 			iova += mapped;
 			paddr += mapped;
 			len -= mapped;
@@ -428,6 +451,10 @@ 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;
+
+err_unmap_pages:
+	mmu_unmap_range(mmu, start_iova, total_mapped);
+	return ret;
 }
 
 int panfrost_mmu_map(struct panfrost_gem_mapping *mapping)
@@ -438,6 +465,7 @@ int panfrost_mmu_map(struct panfrost_gem_mapping *mapping)
 	struct panfrost_device *pfdev = to_panfrost_device(obj->dev);
 	struct sg_table *sgt;
 	int prot = IOMMU_READ | IOMMU_WRITE | IOMMU_CACHE;
+	int ret;
 
 	if (WARN_ON(mapping->active))
 		return 0;
@@ -449,11 +477,18 @@ int panfrost_mmu_map(struct panfrost_gem_mapping *mapping)
 	if (WARN_ON(IS_ERR(sgt)))
 		return PTR_ERR(sgt);
 
-	mmu_map_sg(pfdev, mapping->mmu, mapping->mmnode.start << PAGE_SHIFT,
-		   prot, sgt);
+	ret = mmu_map_sg(pfdev, mapping->mmu, mapping->mmnode.start << PAGE_SHIFT,
+			 prot, sgt);
+	if (ret)
+		goto err_put_pages;
+
 	mapping->active = true;
 
 	return 0;
+
+err_put_pages:
+	drm_gem_shmem_put_pages_locked(shmem);
+	return ret;
 }
 
 void panfrost_mmu_unmap(struct panfrost_gem_mapping *mapping)
@@ -638,8 +673,10 @@ 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_CACHE | IOMMU_NOEXEC, sgt);
+	ret = mmu_map_sg(pfdev, bomapping->mmu, addr,
+			 IOMMU_WRITE | IOMMU_READ | IOMMU_CACHE | IOMMU_NOEXEC, sgt);
+	if (ret)
+		goto err_mmu_map_sg;
 
 	bomapping->active = true;
 	bo->heap_rss_size += SZ_2M;
@@ -653,6 +690,8 @@ static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as,
 
 	return 0;
 
+err_mmu_map_sg:
+	dma_unmap_sgtable(pfdev->base.dev, sgt, DMA_BIDIRECTIONAL, 0);
 err_map:
 	sg_free_table(sgt);
 err_unlock: