On Mon, Apr 7, 2025 at 9:29 AM Maxime Ripard <mrip...@kernel.org> wrote:
Some reserved memory regions might have particular memory setup or
attributes that make them good candidates for heaps.
Let's provide a heap type that will create a new heap for each reserved
memory region flagged as such.
Signed-off-by: Maxime Ripard <mrip...@kernel.org>
This patch looks good to me, but I think it'd be good to add more
justification like you did at
https://lore.kernel.org/all/20240515-dma-buf-ecc-heap-v1-0-54cbbd049...@kernel.org
---
drivers/dma-buf/heaps/Kconfig | 8 +
drivers/dma-buf/heaps/Makefile | 1 +
drivers/dma-buf/heaps/carveout_heap.c | 360 ++++++++++++++++++++++++++++++++++
3 files changed, 369 insertions(+)
diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-buf/heaps/Kconfig
index
a5eef06c422644e8aadaf5aff2bd9a33c49c1ba3..c6981d696733b4d8d0c3f6f5a37d967fd6a1a4a2
100644
--- a/drivers/dma-buf/heaps/Kconfig
+++ b/drivers/dma-buf/heaps/Kconfig
@@ -1,5 +1,13 @@
+config DMABUF_HEAPS_CARVEOUT
+ bool "Carveout Heaps"
+ depends on DMABUF_HEAPS
+ help
+ Choose this option to enable the carveout dmabuf heap. The carveout
+ heap is backed by pages from reserved memory regions flagged as
+ exportable. If in doubt, say Y.
+
config DMABUF_HEAPS_SYSTEM
bool "DMA-BUF System Heap"
depends on DMABUF_HEAPS
help
Choose this option to enable the system dmabuf heap. The system heap
diff --git a/drivers/dma-buf/heaps/Makefile b/drivers/dma-buf/heaps/Makefile
index
974467791032ffb8a7aba17b1407d9a19b3f3b44..b734647ad5c84f449106748160258e372f153df2
100644
--- a/drivers/dma-buf/heaps/Makefile
+++ b/drivers/dma-buf/heaps/Makefile
@@ -1,3 +1,4 @@
# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_DMABUF_HEAPS_CARVEOUT) += carveout_heap.o
obj-$(CONFIG_DMABUF_HEAPS_SYSTEM) += system_heap.o
obj-$(CONFIG_DMABUF_HEAPS_CMA) += cma_heap.o
diff --git a/drivers/dma-buf/heaps/carveout_heap.c
b/drivers/dma-buf/heaps/carveout_heap.c
new file mode 100644
index
0000000000000000000000000000000000000000..f7198b781ea57f4f60e554d917c9277e9a716b16
--- /dev/null
+++ b/drivers/dma-buf/heaps/carveout_heap.c
@@ -0,0 +1,360 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/dma-buf.h>
+#include <linux/dma-heap.h>
+#include <linux/genalloc.h>
+#include <linux/highmem.h>
+#include <linux/of_reserved_mem.h>
+
+struct carveout_heap_priv {
+ struct dma_heap *heap;
+ struct gen_pool *pool;
+};
+
+struct carveout_heap_buffer_priv {
+ struct mutex lock;
+ struct list_head attachments;
+
+ unsigned long num_pages;
+ struct carveout_heap_priv *heap;
+ dma_addr_t daddr;
+ void *vaddr;
+ unsigned int vmap_cnt;
+};
+
+struct carveout_heap_attachment {
+ struct list_head head;
+ struct sg_table table;
+
+ struct device *dev;
+ bool mapped;
+};
+
+static int carveout_heap_attach(struct dma_buf *buf,
+ struct dma_buf_attachment *attachment)
+{
+ struct carveout_heap_buffer_priv *priv = buf->priv;
+ struct carveout_heap_attachment *a;
+ struct sg_table *sgt;
+ unsigned long len = priv->num_pages * PAGE_SIZE;
+ int ret;
+
+ a = kzalloc(sizeof(*a), GFP_KERNEL);
+ if (!a)
+ return -ENOMEM;
+ INIT_LIST_HEAD(&a->head);
+ a->dev = attachment->dev;
+ attachment->priv = a;
+
+ sgt = &a->table;
+ ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
+ if (ret)
+ goto err_cleanup_attach;
+
+ sg_dma_address(sgt->sgl) = priv->daddr;
+ sg_dma_len(sgt->sgl) = len;
+
+ mutex_lock(&priv->lock);
+ list_add(&a->head, &priv->attachments);
+ mutex_unlock(&priv->lock);
+
+ return 0;
+
+err_cleanup_attach:
+ kfree(a);
+ return ret;
+}
+
+static void carveout_heap_detach(struct dma_buf *dmabuf,
+ struct dma_buf_attachment *attachment)
+{
+ struct carveout_heap_buffer_priv *priv = dmabuf->priv;
+ struct carveout_heap_attachment *a = attachment->priv;
+
+ mutex_lock(&priv->lock);
+ list_del(&a->head);
+ mutex_unlock(&priv->lock);
+
+ sg_free_table(&a->table);
+ kfree(a);
+}
+
+static struct sg_table *
+carveout_heap_map_dma_buf(struct dma_buf_attachment *attachment,
+ enum dma_data_direction direction)
+{
+ struct carveout_heap_attachment *a = attachment->priv;
+ struct sg_table *table = &a->table;
+ int ret;
+
+ ret = dma_map_sgtable(a->dev, table, direction, 0);
+ if (ret)
+ return ERR_PTR(-ENOMEM);
Not ERR_PTR(ret)? This is already converted to ENOMEM by
dma_buf_map_attachment before leaving the dmabuf code, but it might be
nice to retain the error type internally. The two existing heaps
aren't consistent about this, and I have a slight preference to
propagate the error here.
+
+ a->mapped = true;
+
+ return table;
+}
+
+static void carveout_heap_unmap_dma_buf(struct dma_buf_attachment *attachment,
+ struct sg_table *table,
+ enum dma_data_direction direction)
+{
+ struct carveout_heap_attachment *a = attachment->priv;
+
+ a->mapped = false;
+ dma_unmap_sgtable(a->dev, table, direction, 0);
+}
+
+static int
+carveout_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
+ enum dma_data_direction direction)
+{
+ struct carveout_heap_buffer_priv *priv = dmabuf->priv;
+ struct carveout_heap_attachment *a;
+ unsigned long len = priv->num_pages * PAGE_SIZE;
+
+ mutex_lock(&priv->lock);
+
+ if (priv->vmap_cnt > 0)
+ invalidate_kernel_vmap_range(priv->vaddr, len);
+
+ list_for_each_entry(a, &priv->attachments, head) {
+ if (!a->mapped)
+ continue;
+
+ dma_sync_sgtable_for_cpu(a->dev, &a->table, direction);
+ }
+
+ mutex_unlock(&priv->lock);
+
+ return 0;
+}
+
+static int
+carveout_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf,
+ enum dma_data_direction direction)
+{
+ struct carveout_heap_buffer_priv *priv = dmabuf->priv;
+ struct carveout_heap_attachment *a;
+ unsigned long len = priv->num_pages * PAGE_SIZE;
+
+ mutex_lock(&priv->lock);
+
+ if (priv->vmap_cnt > 0)
+ flush_kernel_vmap_range(priv->vaddr, len);
+
+ list_for_each_entry(a, &priv->attachments, head) {
+ if (!a->mapped)
+ continue;
+
+ dma_sync_sgtable_for_device(a->dev, &a->table, direction);
+ }
+
+ mutex_unlock(&priv->lock);
+
+ return 0;
+}
+
+static int carveout_heap_mmap(struct dma_buf *dmabuf,
+ struct vm_area_struct *vma)
+{
+ struct carveout_heap_buffer_priv *priv = dmabuf->priv;
+ unsigned long len = priv->num_pages * PAGE_SIZE;
+ struct page *page = virt_to_page(priv->vaddr);
+
+ return remap_pfn_range(vma, vma->vm_start, page_to_pfn(page),
+ len, vma->vm_page_prot);
+}
+
+static int carveout_heap_vmap(struct dma_buf *dmabuf, struct iosys_map *map)
+{
+ struct carveout_heap_buffer_priv *priv = dmabuf->priv;
+
+ mutex_lock(&priv->lock);
+
+ iosys_map_set_vaddr(map, priv->vaddr);
+ priv->vmap_cnt++;
+
+ mutex_unlock(&priv->lock);
+
+ return 0;
+}
+
+static void carveout_heap_vunmap(struct dma_buf *dmabuf, struct iosys_map *map)
+{
+ struct carveout_heap_buffer_priv *priv = dmabuf->priv;
+
+ mutex_lock(&priv->lock);
+
+ priv->vmap_cnt--;
+ mutex_unlock(&priv->lock);
+
+ iosys_map_clear(map);
+}
+
+static void carveout_heap_dma_buf_release(struct dma_buf *buf)
+{
+ struct carveout_heap_buffer_priv *buffer_priv = buf->priv;
+ struct carveout_heap_priv *heap_priv = buffer_priv->heap;
+ unsigned long len = buffer_priv->num_pages * PAGE_SIZE;
+
+ gen_pool_free(heap_priv->pool, (unsigned long)buffer_priv->vaddr, len);
+ kfree(buffer_priv);
+}
+
+static const struct dma_buf_ops carveout_heap_buf_ops = {
+ .attach = carveout_heap_attach,
+ .detach = carveout_heap_detach,
+ .map_dma_buf = carveout_heap_map_dma_buf,
+ .unmap_dma_buf = carveout_heap_unmap_dma_buf,
+ .begin_cpu_access = carveout_heap_dma_buf_begin_cpu_access,
+ .end_cpu_access = carveout_heap_dma_buf_end_cpu_access,
+ .mmap = carveout_heap_mmap,
+ .vmap = carveout_heap_vmap,
+ .vunmap = carveout_heap_vunmap,
+ .release = carveout_heap_dma_buf_release,
+};
+
+static struct dma_buf *carveout_heap_allocate(struct dma_heap *heap,
+ unsigned long len,
+ u32 fd_flags,
+ u64 heap_flags)
+{
+ struct carveout_heap_priv *heap_priv = dma_heap_get_drvdata(heap);
+ struct carveout_heap_buffer_priv *buffer_priv;
+ DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
+ struct dma_buf *buf;
+ dma_addr_t daddr;
+ size_t size = PAGE_ALIGN(len);
This PAGE_ALIGN is not needed since dma_heap_buffer_alloc requires all
heap allocations to be page aligned before this function is called.
+ void *vaddr;
+ int ret;
+
+ buffer_priv = kzalloc(sizeof(*buffer_priv), GFP_KERNEL);
+ if (!buffer_priv)
+ return ERR_PTR(-ENOMEM);
+
+ INIT_LIST_HEAD(&buffer_priv->attachments);
+ mutex_init(&buffer_priv->lock);
+
+ vaddr = gen_pool_dma_zalloc(heap_priv->pool, size, &daddr);
+ if (!vaddr) {
+ ret = -ENOMEM;
+ goto err_free_buffer_priv;
+ }
+
+ buffer_priv->vaddr = vaddr;
+ buffer_priv->daddr = daddr;
+ buffer_priv->heap = heap_priv;
+ buffer_priv->num_pages = size >> PAGE_SHIFT;
+
+ /* create the dmabuf */
+ exp_info.exp_name = dma_heap_get_name(heap);
+ exp_info.ops = &carveout_heap_buf_ops;
+ exp_info.size = size;
+ exp_info.flags = fd_flags;
+ exp_info.priv = buffer_priv;
+
+ buf = dma_buf_export(&exp_info);
+ if (IS_ERR(buf)) {
+ ret = PTR_ERR(buf);
+ goto err_free_buffer;
+ }
+
+ return buf;
+
+err_free_buffer:
+ gen_pool_free(heap_priv->pool, (unsigned long)vaddr, len);
+err_free_buffer_priv:
+ kfree(buffer_priv);
+
+ return ERR_PTR(ret);
+}
+
+static const struct dma_heap_ops carveout_heap_ops = {
+ .allocate = carveout_heap_allocate,
+};
+
+static int __init carveout_heap_setup(struct device_node *node)
+{
+ struct dma_heap_export_info exp_info = {};
+ const struct reserved_mem *rmem;
+ struct carveout_heap_priv *priv;
+ struct dma_heap *heap;
+ struct gen_pool *pool;
+ void *base;
+ int ret;
+
+ rmem = of_reserved_mem_lookup(node);
+ if (!rmem)
+ return -EINVAL;
+
+ priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ pool = gen_pool_create(PAGE_SHIFT, NUMA_NO_NODE);
+ if (!pool) {
+ ret = -ENOMEM;
+ goto err_cleanup_heap;
+ }
+ priv->pool = pool;
+
+ base = memremap(rmem->base, rmem->size, MEMREMAP_WB);
