The only implementor of bdrv_register_buf() is block/nvme.c, where the
size is not needed when unregistering a buffer. This is because
util/vfio-helpers.c can look up mappings by address.
Future block drivers that implement bdrv_register_buf() may not be able
to do their job given only the buffer address. Add a size argument to
bdrv_unregister_buf().
Also document the assumptions about
bdrv_register_buf()/bdrv_unregister_buf() calls. The same <host, size>
values that were given to bdrv_register_buf() must be given to
bdrv_unregister_buf().
gcc 11.2.1 emits a spurious warning that img_bench()'s buf_size local
variable might be uninitialized, so it's necessary to silence the
compiler.
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
---
include/block/block-global-state.h | 5 ++++-
include/block/block_int-common.h | 2 +-
include/sysemu/block-backend-global-state.h | 2 +-
block/block-backend.c | 4 ++--
block/io.c | 6 +++---
block/nvme.c | 2 +-
qemu-img.c | 4 ++--
7 files changed, 14 insertions(+), 11 deletions(-)
diff --git a/include/block/block-global-state.h
b/include/block/block-global-state.h
index 21265e3966..7901f35863 100644
--- a/include/block/block-global-state.h
+++ b/include/block/block-global-state.h
@@ -243,9 +243,12 @@ void bdrv_del_child(BlockDriverState *parent, BdrvChild
*child, Error **errp);
* 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.
+ *
+ * Buffers must not overlap and they must be unregistered with the same <host,
+ * size> values that they were registered with.
*/
void bdrv_register_buf(BlockDriverState *bs, void *host, size_t size);
-void bdrv_unregister_buf(BlockDriverState *bs, void *host);
+void bdrv_unregister_buf(BlockDriverState *bs, void *host, size_t size);
void bdrv_cancel_in_flight(BlockDriverState *bs);
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index 8947abab76..b7a7cbd3a5 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -435,7 +435,7 @@ struct BlockDriver {
* DMA mapping for hot buffers.
*/
void (*bdrv_register_buf)(BlockDriverState *bs, void *host, size_t size);
- void (*bdrv_unregister_buf)(BlockDriverState *bs, void *host);
+ void (*bdrv_unregister_buf)(BlockDriverState *bs, void *host, size_t size);
/*
* This field is modified only under the BQL, and is part of
diff --git a/include/sysemu/block-backend-global-state.h
b/include/sysemu/block-backend-global-state.h
index 415f0c91d7..97f7dad2c3 100644
--- a/include/sysemu/block-backend-global-state.h
+++ b/include/sysemu/block-backend-global-state.h
@@ -107,7 +107,7 @@ 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);
+void blk_unregister_buf(BlockBackend *blk, void *host, size_t size);
const BdrvChild *blk_root(BlockBackend *blk);
diff --git a/block/block-backend.c b/block/block-backend.c
index d4a5df2ac2..99141f8f06 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -2551,10 +2551,10 @@ 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)
+void blk_unregister_buf(BlockBackend *blk, void *host, size_t size)
{
GLOBAL_STATE_CODE();
- bdrv_unregister_buf(blk_bs(blk), host);
+ bdrv_unregister_buf(blk_bs(blk), host, size);
}
int coroutine_fn blk_co_copy_range(BlockBackend *blk_in, int64_t off_in,
diff --git a/block/io.c b/block/io.c
index 0a8cbefe86..af85fa4bcc 100644
--- a/block/io.c
+++ b/block/io.c
@@ -3305,16 +3305,16 @@ void bdrv_register_buf(BlockDriverState *bs, void
*host, size_t size)
}
}
-void bdrv_unregister_buf(BlockDriverState *bs, void *host)
+void bdrv_unregister_buf(BlockDriverState *bs, void *host, size_t size)
{
BdrvChild *child;
GLOBAL_STATE_CODE();
if (bs->drv && bs->drv->bdrv_unregister_buf) {
- bs->drv->bdrv_unregister_buf(bs, host);
+ bs->drv->bdrv_unregister_buf(bs, host, size);
}
QLIST_FOREACH(child, &bs->children, next) {
- bdrv_unregister_buf(child->bs, host);
+ bdrv_unregister_buf(child->bs, host, size);
}
}
diff --git a/block/nvme.c b/block/nvme.c
index 01fb28aa63..696502acea 100644
--- a/block/nvme.c
+++ b/block/nvme.c
@@ -1592,7 +1592,7 @@ static void nvme_register_buf(BlockDriverState *bs, void
*host, size_t size)
}
}
-static void nvme_unregister_buf(BlockDriverState *bs, void *host)
+static void nvme_unregister_buf(BlockDriverState *bs, void *host, size_t size)
{
BDRVNVMeState *s = bs->opaque;
diff --git a/qemu-img.c b/qemu-img.c
index 7d4b33b3da..b8a8818ddb 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -4368,7 +4368,7 @@ static int img_bench(int argc, char **argv)
struct timeval t1, t2;
int i;
bool force_share = false;
- size_t buf_size;
+ size_t buf_size = 0;
for (;;) {
static const struct option long_options[] = {
@@ -4590,7 +4590,7 @@ static int img_bench(int argc, char **argv)
out:
if (data.buf) {
- blk_unregister_buf(blk, data.buf);
+ blk_unregister_buf(blk, data.buf, buf_size);
}
qemu_vfree(data.buf);
blk_unref(blk);
--
2.37.3
