Each importer can now provide an invalidate_mappings callback.

This allows the exporter to provide the mappings without the need to pin the backing store.

Signed-off-by: Christian König christian.koenig@amd.com --- drivers/dma-buf/dma-buf.c | 25 +++++++++++++++++++++++++ include/linux/dma-buf.h | 36 ++++++++++++++++++++++++++++++++++++ 2 files changed, 61 insertions(+)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index d78d5fc173dc..ed8d5844ae74 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -629,6 +629,9 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,

might_sleep();

+ if (attach->invalidate_mappings) + reservation_object_assert_held(attach->dmabuf->resv); + if (WARN_ON(!attach || !attach->dmabuf)) return ERR_PTR(-EINVAL);

@@ -656,6 +659,9 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach, { might_sleep();

+ if (attach->invalidate_mappings) + reservation_object_assert_held(attach->dmabuf->resv); + if (WARN_ON(!attach || !attach->dmabuf || !sg_table)) return;

@@ -664,6 +670,25 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach, } EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);

+/** + * dma_buf_invalidate_mappings - invalidate all mappings of this dma_buf + * + * @dmabuf: [in] buffer which mappings should be invalidated + * + * Informs all attachmenst that they need to destroy and recreated all their + * mappings. + */ +void dma_buf_invalidate_mappings(struct dma_buf *dmabuf) +{ + struct dma_buf_attachment *attach; + + reservation_object_assert_held(dmabuf->resv); + + list_for_each_entry(attach, &dmabuf->attachments, node) + attach->invalidate_mappings(attach); +} +EXPORT_SYMBOL_GPL(dma_buf_invalidate_mappings); + /** * DOC: cpu access * diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index 085db2fee2d7..c1e2f7d93509 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -91,6 +91,18 @@ struct dma_buf_ops { */ void (*detach)(struct dma_buf *, struct dma_buf_attachment *);

+ /** + * @supports_mapping_invalidation: + * + * True for exporters which supports unpinned DMA-buf operation using + * the reservation lock. + * + * When attachment->invalidate_mappings is set the @map_dma_buf and + * @unmap_dma_buf callbacks can be called with the reservation lock + * held. + */ + bool supports_mapping_invalidation; + /** * @map_dma_buf: * @@ -326,6 +338,29 @@ struct dma_buf_attachment { struct device *dev; struct list_head node; void *priv; + + /** + * @invalidate_mappings: + * + * Optional callback provided by the importer of the attachment which + * must be set before mappings are created. + * + * If provided the exporter can avoid pinning the backing store while + * mappings exists. + * + * The function is called with the lock of the reservation object + * associated with the dma_buf held and the mapping function must be + * called with this lock held as well. This makes sure that no mapping + * is created concurrently with an ongoing invalidation. + * + * After the callback all existing mappings are still valid until all + * fences in the dma_bufs reservation object are signaled, but should be + * destroyed by the importer as soon as possible. + * + * New mappings can be created immediately, but can't be used before the + * exclusive fence in the dma_bufs reservation object is signaled. + */ + void (*invalidate_mappings)(struct dma_buf_attachment *attach); };

/** @@ -391,6 +426,7 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *, enum dma_data_direction); void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *, enum dma_data_direction); +void dma_buf_invalidate_mappings(struct dma_buf *dma_buf); int dma_buf_begin_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction dir); int dma_buf_end_cpu_access(struct dma_buf *dma_buf,