block: Introduce buf register API

Allow block driver to map and unmap a buffer for later I/O, as a performance
hint.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20180116060901.17413-5-famz@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
This commit is contained in:
Fam Zheng 2018-01-16 14:08:56 +08:00
parent bdd6a90a9e
commit 23d0ba9319
5 changed files with 56 additions and 1 deletions

View file

@ -631,5 +631,14 @@ void bdrv_del_child(BlockDriverState *parent, BdrvChild *child, Error **errp);
bool bdrv_can_store_new_dirty_bitmap(BlockDriverState *bs, const char *name,
uint32_t granularity, Error **errp);
/**
*
* bdrv_register_buf/bdrv_unregister_buf:
*
* Register/unregister a buffer for I/O. For example, VFIO drivers are
* interested to know the memory areas that would later be used for I/O, so
* that they can prepare IOMMU mapping etc., to get better performance.
*/
void bdrv_register_buf(BlockDriverState *bs, void *host, size_t size);
void bdrv_unregister_buf(BlockDriverState *bs, void *host);
#endif

View file

@ -446,6 +446,15 @@ struct BlockDriver {
const char *name,
Error **errp);
/**
* Register/unregister a buffer for I/O. For example, when the driver is
* interested to know the memory areas that will later be used in iovs, so
* that it can do IOMMU mapping with VFIO etc., in order to get better
* performance. In the case of VFIO drivers, this callback is used to do
* DMA mapping for hot buffers.
*/
void (*bdrv_register_buf)(BlockDriverState *bs, void *host, size_t size);
void (*bdrv_unregister_buf)(BlockDriverState *bs, void *host);
QLIST_ENTRY(BlockDriver) list;
};