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Merge tag 'block-pull-request' of https://gitlab.com/stefanha/qemu into staging

Pull request

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# gpg: Signature made Mon 23 Jan 2023 20:04:13 GMT
# gpg:                using RSA key 8695A8BFD3F97CDAAC35775A9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>" [full]
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>" [full]
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* tag 'block-pull-request' of https://gitlab.com/stefanha/qemu:
  block/blkio: Fix inclusion of required headers
  virtio-blk: simplify virtio_blk_dma_restart_cb()
  util/aio: Defer disabling poll mode as long as possible

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Peter Maydell 2023-01-24 09:45:33 +00:00
commit 13356edb87
5 changed files with 43 additions and 45 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
block/blkio.c
View File

@ -19,6 +19,8 @@
#include "qemu/module.h"
#include "exec/memory.h" /* for ram_block_discard_disable() */
#include "block/block-io.h"
/*
* Keep the QEMU BlockDriver names identical to the libblkio driver names.
* Using macros instead of typing out the string literals avoids typos.

17
hw/block/dataplane/virtio-blk.c
View File

@ -237,9 +237,6 @@ int virtio_blk_data_plane_start(VirtIODevice *vdev)
goto fail_aio_context;
}
/* Process queued requests before the ones in vring */
virtio_blk_process_queued_requests(vblk, false);
/* Kick right away to begin processing requests already in vring */
for (i = 0; i < nvqs; i++) {
VirtQueue *vq = virtio_get_queue(s->vdev, i);
@ -272,11 +269,6 @@ int virtio_blk_data_plane_start(VirtIODevice *vdev)
fail_host_notifiers:
k->set_guest_notifiers(qbus->parent, nvqs, false);
fail_guest_notifiers:
/*
* If we failed to set up the guest notifiers queued requests will be
* processed on the main context.
*/
virtio_blk_process_queued_requests(vblk, false);
vblk->dataplane_disabled = true;
s->starting = false;
vblk->dataplane_started = true;
@ -325,8 +317,13 @@ void virtio_blk_data_plane_stop(VirtIODevice *vdev)
aio_context_acquire(s->ctx);
aio_wait_bh_oneshot(s->ctx, virtio_blk_data_plane_stop_bh, s);
/* Drain and try to switch bs back to the QEMU main loop. If other users
* keep the BlockBackend in the iothread, that's ok */
/* Wait for virtio_blk_dma_restart_bh() and in flight I/O to complete */
blk_drain(s->conf->conf.blk);
/*
* Try to switch bs back to the QEMU main loop. If other users keep the
* BlockBackend in the iothread, that's ok
*/
blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context(), NULL);
aio_context_release(s->ctx);

42
hw/block/virtio-blk.c
View File

@ -806,8 +806,10 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
virtio_blk_handle_vq(s, vq);
}
void virtio_blk_process_queued_requests(VirtIOBlock *s, bool is_bh)
static void virtio_blk_dma_restart_bh(void *opaque)
{
VirtIOBlock *s = opaque;
VirtIOBlockReq *req = s->rq;
MultiReqBuffer mrb = {};
@ -834,43 +836,27 @@ void virtio_blk_process_queued_requests(VirtIOBlock *s, bool is_bh)
if (mrb.num_reqs) {
virtio_blk_submit_multireq(s, &mrb);
}
if (is_bh) {
/* Paired with inc in virtio_blk_dma_restart_cb() */
blk_dec_in_flight(s->conf.conf.blk);
}
aio_context_release(blk_get_aio_context(s->conf.conf.blk));
}
static void virtio_blk_dma_restart_bh(void *opaque)
{
VirtIOBlock *s = opaque;
qemu_bh_delete(s->bh);
s->bh = NULL;
virtio_blk_process_queued_requests(s, true);
}
static void virtio_blk_dma_restart_cb(void *opaque, bool running,
RunState state)
{
VirtIOBlock *s = opaque;
BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
VirtioBusState *bus = VIRTIO_BUS(qbus);
if (!running) {
return;
}
/*
* If ioeventfd is enabled, don't schedule the BH here as queued
* requests will be processed while starting the data plane.
*/
if (!s->bh && !virtio_bus_ioeventfd_enabled(bus)) {
s->bh = aio_bh_new(blk_get_aio_context(s->conf.conf.blk),
virtio_blk_dma_restart_bh, s);
/* Paired with dec in virtio_blk_dma_restart_bh() */
blk_inc_in_flight(s->conf.conf.blk);
qemu_bh_schedule(s->bh);
}
aio_bh_schedule_oneshot(blk_get_aio_context(s->conf.conf.blk),
virtio_blk_dma_restart_bh, s);
}
static void virtio_blk_reset(VirtIODevice *vdev)
@ -1213,7 +1199,13 @@ static void virtio_blk_device_realize(DeviceState *dev, Error **errp)
return;
}
s->change = qemu_add_vm_change_state_handler(virtio_blk_dma_restart_cb, s);
/*
* This must be after virtio_init() so virtio_blk_dma_restart_cb() gets
* called after ->start_ioeventfd() has already set blk's AioContext.
*/
s->change =
qdev_add_vm_change_state_handler(dev, virtio_blk_dma_restart_cb, s);
blk_ram_registrar_init(&s->blk_ram_registrar, s->blk);
blk_set_dev_ops(s->blk, &virtio_block_ops, s);

2
include/hw/virtio/virtio-blk.h
View File

@ -55,7 +55,6 @@ struct VirtIOBlock {
VirtIODevice parent_obj;
BlockBackend *blk;
void *rq;
QEMUBH *bh;
VirtIOBlkConf conf;
unsigned short sector_mask;
bool original_wce;
@ -93,6 +92,5 @@ typedef struct MultiReqBuffer {
} MultiReqBuffer;
void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq);
void virtio_blk_process_queued_requests(VirtIOBlock *s, bool is_bh);
#endif

21
util/aio-posix.c
View File

@ -585,18 +585,16 @@ static bool try_poll_mode(AioContext *ctx, AioHandlerList *ready_list,
max_ns = qemu_soonest_timeout(*timeout, ctx->poll_ns);
if (max_ns && !ctx->fdmon_ops->need_wait(ctx)) {
/*
* Enable poll mode. It pairs with the poll_set_started() in
* aio_poll() which disables poll mode.
*/
poll_set_started(ctx, ready_list, true);
if (run_poll_handlers(ctx, ready_list, max_ns, timeout)) {
return true;
}
}
if (poll_set_started(ctx, ready_list, false)) {
*timeout = 0;
return true;
}
return false;
}
@ -657,6 +655,17 @@ bool aio_poll(AioContext *ctx, bool blocking)
* system call---a single round of run_poll_handlers_once suffices.
*/
if (timeout || ctx->fdmon_ops->need_wait(ctx)) {
/*
* Disable poll mode. poll mode should be disabled before the call
* of ctx->fdmon_ops->wait() so that guest's notification can wake
* up IO threads when some work becomes pending. It is essential to
* avoid hangs or unnecessary latency.
*/
if (poll_set_started(ctx, &ready_list, false)) {
timeout = 0;
progress = true;
}
ctx->fdmon_ops->wait(ctx, &ready_list, timeout);
}