Allow block driver to map and unmap a buffer for later I/O, as a performance
hint.
Signed-off-by: Fam Zheng <f...@redhat.com>
Message-Id: <20180110091846.10699-5-f...@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com>
---
block/block-backend.c | 10 ++++++++++
block/io.c | 24 ++++++++++++++++++++++++
include/block/block.h | 11 ++++++++++-
include/block/block_int.h | 9 +++++++++
include/sysemu/block-backend.h | 3 +++
5 files changed, 56 insertions(+), 1 deletion(-)
diff --git a/block/block-backend.c b/block/block-backend.c
index baef8e7abc..f66349c2c9 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -2096,3 +2096,13 @@ static void blk_root_drained_end(BdrvChild *child)
}
}
}
+
+void blk_register_buf(BlockBackend *blk, void *host, size_t size)
+{
+ bdrv_register_buf(blk_bs(blk), host, size);
+}
+
+void blk_unregister_buf(BlockBackend *blk, void *host)
+{
+ bdrv_unregister_buf(blk_bs(blk), host);
+}
diff --git a/block/io.c b/block/io.c
index 7ea402352e..89d0745e95 100644
--- a/block/io.c
+++ b/block/io.c
@@ -2825,3 +2825,27 @@ void bdrv_io_unplug(BlockDriverState *bs)
bdrv_io_unplug(child->bs);
}
}
+
+void bdrv_register_buf(BlockDriverState *bs, void *host, size_t size)
+{
+ BdrvChild *child;
+
+ if (bs->drv && bs->drv->bdrv_register_buf) {
+ bs->drv->bdrv_register_buf(bs, host, size);
+ }
+ QLIST_FOREACH(child, &bs->children, next) {
+ bdrv_register_buf(child->bs, host, size);
+ }
+}
+
+void bdrv_unregister_buf(BlockDriverState *bs, void *host)
+{
+ BdrvChild *child;
+
+ if (bs->drv && bs->drv->bdrv_unregister_buf) {
+ bs->drv->bdrv_unregister_buf(bs, host);
+ }
+ QLIST_FOREACH(child, &bs->children, next) {
+ bdrv_unregister_buf(child->bs, host);
+ }
+}
diff --git a/include/block/block.h b/include/block/block.h
index 9b12774ddf..2025d7ed19 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -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
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 29cafa4236..99b9190627 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -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;
};
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index c4e52a5fa3..92ab624fac 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -229,4 +229,7 @@ void blk_io_limits_enable(BlockBackend *blk, const char
*group);
void blk_io_limits_update_group(BlockBackend *blk, const char *group);
void blk_set_force_allow_inactivate(BlockBackend *blk);
+void blk_register_buf(BlockBackend *blk, void *host, size_t size);
+void blk_unregister_buf(BlockBackend *blk, void *host);
+
#endif
--
2.14.3
