From 4f384011c5a37f80dc6cadefffac61ffb1c3aa1e Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Thu, 13 Oct 2022 14:58:59 -0400 Subject: [PATCH] block: pass size to bdrv_unregister_buf() 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 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 Reviewed-by: Stefano Garzarella Message-id: 20221013185908.1297568-5-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi --- block/block-backend.c | 4 ++-- block/io.c | 6 +++--- block/nvme.c | 2 +- include/block/block-global-state.h | 5 ++++- include/block/block_int-common.h | 2 +- include/sysemu/block-backend-global-state.h | 2 +- qemu-img.c | 4 ++-- 7 files changed, 14 insertions(+), 11 deletions(-) diff --git a/block/block-backend.c b/block/block-backend.c index aa4adf06ae89..ae4247489129 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 d30073036ef0..cca402bf7bcd 100644 --- a/block/io.c +++ b/block/io.c @@ -3275,16 +3275,16 @@ 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 2b24f951642d..94b76b16f2a3 100644 --- a/block/nvme.c +++ b/block/nvme.c @@ -1602,7 +1602,7 @@ 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/include/block/block-global-state.h b/include/block/block-global-state.h index 21265e396685..7901f3586305 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 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 8947abab7605..b7a7cbd3a58d 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 415f0c91d764..97f7dad2c340 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/qemu-img.c b/qemu-img.c index ace3adf8aea4..9fe94df650f9 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -4371,7 +4371,7 @@ 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[] = { @@ -4593,7 +4593,7 @@ 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);