hw/virtio: generalise CHR_EVENT_CLOSED handling
..and use for both virtio-user-blk and virtio-user-gpio. This avoids the circular close by deferring shutdown due to disconnection until a later point. virtio-user-blk already had this mechanism in place so generalise it as a vhost-user helper function and use for both blk and gpio devices. While we are at it we also fix up vhost-user-gpio to re-establish the event handler after close down so we can reconnect later. Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Raphael Norwitz <raphael.norwitz@nutanix.com> Message-Id: <20221130112439.2527228-5-alex.bennee@linaro.org> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Alex Bennée
Michael S. Tsirkin
parent
060f4a9440
commit
71e076a07d
@ -369,17 +369,10 @@ static void vhost_user_blk_disconnect(DeviceState *dev)
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vhost_user_blk_stop(vdev);
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vhost_dev_cleanup(&s->dev);
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}
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static void vhost_user_blk_chr_closed_bh(void *opaque)
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{
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DeviceState *dev = opaque;
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VirtIODevice *vdev = VIRTIO_DEVICE(dev);
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VHostUserBlk *s = VHOST_USER_BLK(vdev);
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vhost_user_blk_disconnect(dev);
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/* Re-instate the event handler for new connections */
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qemu_chr_fe_set_handlers(&s->chardev, NULL, NULL, vhost_user_blk_event,
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NULL, opaque, NULL, true);
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NULL, dev, NULL, true);
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}
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static void vhost_user_blk_event(void *opaque, QEMUChrEvent event)
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@ -398,33 +391,9 @@ static void vhost_user_blk_event(void *opaque, QEMUChrEvent event)
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}
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break;
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case CHR_EVENT_CLOSED:
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if (!runstate_check(RUN_STATE_SHUTDOWN)) {
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/*
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* A close event may happen during a read/write, but vhost
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* code assumes the vhost_dev remains setup, so delay the
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* stop & clear.
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*/
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AioContext *ctx = qemu_get_current_aio_context();
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qemu_chr_fe_set_handlers(&s->chardev, NULL, NULL, NULL, NULL,
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NULL, NULL, false);
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aio_bh_schedule_oneshot(ctx, vhost_user_blk_chr_closed_bh, opaque);
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/*
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* Move vhost device to the stopped state. The vhost-user device
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* will be clean up and disconnected in BH. This can be useful in
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* the vhost migration code. If disconnect was caught there is an
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* option for the general vhost code to get the dev state without
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* knowing its type (in this case vhost-user).
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*
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* FIXME: this is sketchy to be reaching into vhost_dev
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* now because we are forcing something that implies we
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* have executed vhost_dev_stop() but that won't happen
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* until vhost_user_blk_stop() gets called from the bh.
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* Really this state check should be tracked locally.
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*/
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s->dev.started = false;
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}
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/* defer close until later to avoid circular close */
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vhost_user_async_close(dev, &s->chardev, &s->dev,
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vhost_user_blk_disconnect);
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break;
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case CHR_EVENT_BREAK:
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case CHR_EVENT_MUX_IN:
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@ -233,6 +233,8 @@ static int vu_gpio_connect(DeviceState *dev, Error **errp)
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return 0;
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}
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static void vu_gpio_event(void *opaque, QEMUChrEvent event);
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static void vu_gpio_disconnect(DeviceState *dev)
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{
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VirtIODevice *vdev = VIRTIO_DEVICE(dev);
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@ -245,6 +247,11 @@ static void vu_gpio_disconnect(DeviceState *dev)
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vu_gpio_stop(vdev);
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vhost_dev_cleanup(&gpio->vhost_dev);
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/* Re-instate the event handler for new connections */
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qemu_chr_fe_set_handlers(&gpio->chardev,
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NULL, NULL, vu_gpio_event,
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NULL, dev, NULL, true);
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}
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static void vu_gpio_event(void *opaque, QEMUChrEvent event)
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@ -262,7 +269,9 @@ static void vu_gpio_event(void *opaque, QEMUChrEvent event)
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}
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break;
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case CHR_EVENT_CLOSED:
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vu_gpio_disconnect(dev);
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/* defer close until later to avoid circular close */
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vhost_user_async_close(dev, &gpio->chardev, &gpio->vhost_dev,
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vu_gpio_disconnect);
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break;
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case CHR_EVENT_BREAK:
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case CHR_EVENT_MUX_IN:
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@ -21,6 +21,7 @@
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#include "qemu/error-report.h"
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#include "qemu/main-loop.h"
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#include "qemu/sockets.h"
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#include "sysemu/runstate.h"
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#include "sysemu/cryptodev.h"
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#include "migration/migration.h"
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#include "migration/postcopy-ram.h"
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@ -2670,6 +2671,76 @@ void vhost_user_cleanup(VhostUserState *user)
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user->chr = NULL;
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}
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typedef struct {
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vu_async_close_fn cb;
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DeviceState *dev;
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CharBackend *cd;
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struct vhost_dev *vhost;
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} VhostAsyncCallback;
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static void vhost_user_async_close_bh(void *opaque)
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{
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VhostAsyncCallback *data = opaque;
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struct vhost_dev *vhost = data->vhost;
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/*
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* If the vhost_dev has been cleared in the meantime there is
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* nothing left to do as some other path has completed the
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* cleanup.
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*/
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if (vhost->vdev) {
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data->cb(data->dev);
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}
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g_free(data);
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}
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/*
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* We only schedule the work if the machine is running. If suspended
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* we want to keep all the in-flight data as is for migration
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* purposes.
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*/
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void vhost_user_async_close(DeviceState *d,
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CharBackend *chardev, struct vhost_dev *vhost,
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vu_async_close_fn cb)
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{
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if (!runstate_check(RUN_STATE_SHUTDOWN)) {
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/*
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* A close event may happen during a read/write, but vhost
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* code assumes the vhost_dev remains setup, so delay the
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* stop & clear.
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*/
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AioContext *ctx = qemu_get_current_aio_context();
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VhostAsyncCallback *data = g_new0(VhostAsyncCallback, 1);
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/* Save data for the callback */
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data->cb = cb;
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data->dev = d;
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data->cd = chardev;
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data->vhost = vhost;
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/* Disable any further notifications on the chardev */
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qemu_chr_fe_set_handlers(chardev,
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NULL, NULL, NULL, NULL, NULL, NULL,
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false);
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aio_bh_schedule_oneshot(ctx, vhost_user_async_close_bh, data);
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/*
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* Move vhost device to the stopped state. The vhost-user device
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* will be clean up and disconnected in BH. This can be useful in
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* the vhost migration code. If disconnect was caught there is an
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* option for the general vhost code to get the dev state without
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* knowing its type (in this case vhost-user).
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*
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* Note if the vhost device is fully cleared by the time we
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* execute the bottom half we won't continue with the cleanup.
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*/
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vhost->started = false;
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}
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}
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static int vhost_user_dev_start(struct vhost_dev *dev, bool started)
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{
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if (!virtio_has_feature(dev->protocol_features,
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@ -68,4 +68,22 @@ bool vhost_user_init(VhostUserState *user, CharBackend *chr, Error **errp);
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*/
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void vhost_user_cleanup(VhostUserState *user);
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/**
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* vhost_user_async_close() - cleanup vhost-user post connection drop
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* @d: DeviceState for the associated device (passed to callback)
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* @chardev: the CharBackend associated with the connection
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* @vhost: the common vhost device
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* @cb: the user callback function to complete the clean-up
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*
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* This function is used to handle the shutdown of a vhost-user
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* connection to a backend. We handle this centrally to make sure we
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* do all the steps and handle potential races due to VM shutdowns.
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* Once the connection is disabled we call a backhalf to ensure
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*/
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typedef void (*vu_async_close_fn)(DeviceState *cb);
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void vhost_user_async_close(DeviceState *d,
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CharBackend *chardev, struct vhost_dev *vhost,
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vu_async_close_fn cb);
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#endif
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