[Qemu-devel] [RESEND] [PATCH 0/6] virtio: refactor host notifiers

[Qemu-devel] [RESEND] [PATCH 0/6] virtio: refactor host notifiers

[Cornelia Huck]

Hi,

this is a resend of the host notifier refactoring I last sent out
on 2016/04/25. Just rebased on current master and pushed out to
github.com/cohuck/qemu host-notifier-refactor.

Blurb from the last posting follows:

This still fixes an issue where we have no ioeventfd for a short
time, but it does not break our necks any more with the recent
fixes. Still, I think this is a net win, especially considering
we remove a lot of similar code from the individual transports.

Cornelia Huck (6):
  virtio-bus: common ioeventfd infrastructure
  virtio-bus: have callers tolerate new host notifier api
  virtio-ccw: convert to ioeventfd callbacks
  virtio-pci: convert to ioeventfd callbacks
  virtio-mmio: convert to ioeventfd callbacks
  virtio-bus: remove old set_host_notifier callback

 hw/block/dataplane/virtio-blk.c |   6 +-
 hw/s390x/virtio-ccw.c           | 133 ++++++++++++++--------------------------
 hw/scsi/virtio-scsi-dataplane.c |   9 ++-
 hw/virtio/vhost.c               |  13 ++--
 hw/virtio/virtio-bus.c          | 132 +++++++++++++++++++++++++++++++++++++++
 hw/virtio/virtio-mmio.c         | 128 +++++++++++++-------------------------
 hw/virtio/virtio-pci.c          | 124 +++++++++++++------------------------
 include/hw/virtio/virtio-bus.h  |  31 +++++++++-
 8 files changed, 303 insertions(+), 273 deletions(-)

-- 
2.6.6

[Qemu-devel] [PATCH 1/6] virtio-bus: common ioeventfd infrastructure

[Cornelia Huck]

Introduce a set of ioeventfd callbacks on the virtio-bus level
that can be implemented by the individual transports. At the
virtio-bus level, do common handling for host notifiers (which
is actually most of it).

Two things of note:
- When setting the host notifier, we only switch from/to the
  generic ioeventfd handler. This fixes a latent bug where we
  had no ioeventfd assigned for a certain window.
- We always iterate over all possible virtio queues, even though
  ccw (currently) has a lower limit. It does not really matter
  here.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 hw/virtio/virtio-bus.c         | 132 +++++++++++++++++++++++++++++++++++++++++
 include/hw/virtio/virtio-bus.h |  30 ++++++++++
 2 files changed, 162 insertions(+)

diff --git a/hw/virtio/virtio-bus.c b/hw/virtio/virtio-bus.c
index 574f0e2..1313760 100644
--- a/hw/virtio/virtio-bus.c
+++ b/hw/virtio/virtio-bus.c
@@ -146,6 +146,138 @@ void virtio_bus_set_vdev_config(VirtioBusState *bus, uint8_t *config)
     }
 }
 
+/*
+ * This function handles both assigning the ioeventfd handler and
+ * registering it with the kernel.
+ * assign: register/deregister ioeventfd with the kernel
+ * set_handler: use the generic ioeventfd handler
+ */
+static int set_host_notifier_internal(DeviceState *proxy, VirtioBusState *bus,
+                                      int n, bool assign, bool set_handler)
+{
+    VirtIODevice *vdev = virtio_bus_get_device(bus);
+    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
+    VirtQueue *vq = virtio_get_queue(vdev, n);
+    EventNotifier *notifier = virtio_queue_get_host_notifier(vq);
+    int r = 0;
+
+    if (assign) {
+        r = event_notifier_init(notifier, 1);
+        if (r < 0) {
+            error_report("%s: unable to init event notifier: %d", __func__, r);
+            return r;
+        }
+        virtio_queue_set_host_notifier_fd_handler(vq, true, set_handler);
+        r = k->ioeventfd_assign(proxy, notifier, n, assign);
+        if (r < 0) {
+            error_report("%s: unable to assign ioeventfd: %d", __func__, r);
+            virtio_queue_set_host_notifier_fd_handler(vq, false, false);
+            event_notifier_cleanup(notifier);
+            return r;
+        }
+    } else {
+        virtio_queue_set_host_notifier_fd_handler(vq, false, false);
+        k->ioeventfd_assign(proxy, notifier, n, assign);
+        event_notifier_cleanup(notifier);
+    }
+    return r;
+}
+
+void virtio_bus_start_ioeventfd(VirtioBusState *bus)
+{
+    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
+    DeviceState *proxy = DEVICE(BUS(bus)->parent);
+    VirtIODevice *vdev;
+    int n, r;
+
+    if (!k->ioeventfd_started || k->ioeventfd_started(proxy)) {
+        return;
+    }
+    if (k->ioeventfd_disabled(proxy)) {
+        return;
+    }
+    vdev = virtio_bus_get_device(bus);
+    for (n = 0; n < VIRTIO_QUEUE_MAX; n++) {
+        if (!virtio_queue_get_num(vdev, n)) {
+            continue;
+        }
+        r = set_host_notifier_internal(proxy, bus, n, true, true);
+        if (r < 0) {
+            goto assign_error;
+        }
+    }
+    k->ioeventfd_set_started(proxy, true, false);
+    return;
+
+assign_error:
+    while (--n >= 0) {
+        if (!virtio_queue_get_num(vdev, n)) {
+            continue;
+        }
+
+        r = set_host_notifier_internal(proxy, bus, n, false, false);
+        assert(r >= 0);
+    }
+    k->ioeventfd_set_started(proxy, false, true);
+    error_report("%s: failed. Fallback to userspace (slower).", __func__);
+}
+
+void virtio_bus_stop_ioeventfd(VirtioBusState *bus)
+{
+    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
+    DeviceState *proxy = DEVICE(BUS(bus)->parent);
+    VirtIODevice *vdev;
+    int n, r;
+
+    if (!k->ioeventfd_started || !k->ioeventfd_started(proxy)) {
+        return;
+    }
+    vdev = virtio_bus_get_device(bus);
+    for (n = 0; n < VIRTIO_QUEUE_MAX; n++) {
+        if (!virtio_queue_get_num(vdev, n)) {
+            continue;
+        }
+        r = set_host_notifier_internal(proxy, bus, n, false, false);
+        assert(r >= 0);
+    }
+    k->ioeventfd_set_started(proxy, false, false);
+}
+
+/*
+ * This function switches from/to the generic ioeventfd handler.
+ * assign==false means 'use generic ioeventfd handler'.
+ */
+int virtio_bus_set_host_notifier(VirtioBusState *bus, int n, bool assign)
+{
+    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
+    DeviceState *proxy = DEVICE(BUS(bus)->parent);
+    VirtIODevice *vdev = virtio_bus_get_device(bus);
+    VirtQueue *vq = virtio_get_queue(vdev, n);
+
+    if (!k->ioeventfd_started) {
+        return -ENOSYS;
+    }
+    if (assign) {
+        /*
+         * Stop using the generic ioeventfd, we are doing eventfd handling
+         * ourselves below
+         */
+        k->ioeventfd_set_disabled(proxy, true);
+    }
+    /*
+     * Just switch the handler, don't deassign the ioeventfd.
+     * Otherwise, there's a window where we don't have an
+     * ioeventfd and we may end up with a notification where
+     * we don't expect one.
+     */
+    virtio_queue_set_host_notifier_fd_handler(vq, assign, !assign);
+    if (!assign) {
+        /* Use generic ioeventfd handler again. */
+        k->ioeventfd_set_disabled(proxy, false);
+    }
+    return 0;
+}
+
 static char *virtio_bus_get_dev_path(DeviceState *dev)
 {
     BusState *bus = qdev_get_parent_bus(dev);
diff --git a/include/hw/virtio/virtio-bus.h b/include/hw/virtio/virtio-bus.h
index 3f2c136..9637f80 100644
--- a/include/hw/virtio/virtio-bus.h
+++ b/include/hw/virtio/virtio-bus.h
@@ -71,6 +71,29 @@ typedef struct VirtioBusClass {
     void (*device_unplugged)(DeviceState *d);
     int (*query_nvectors)(DeviceState *d);
     /*
+     * ioeventfd handling: if the transport implements ioeventfd_started,
+     * it must implement the other ioeventfd callbacks as well
+     */
+    /* Returns true if the ioeventfd has been started for the device. */
+    bool (*ioeventfd_started)(DeviceState *d);
+    /*
+     * Sets the 'ioeventfd started' state after the ioeventfd has been
+     * started/stopped for the device. err signifies whether an error
+     * had occurred.
+     */
+    void (*ioeventfd_set_started)(DeviceState *d, bool started, bool err);
+    /* Returns true if the ioeventfd has been disabled for the device. */
+    bool (*ioeventfd_disabled)(DeviceState *d);
+    /* Sets the 'ioeventfd disabled' state for the device. */
+    void (*ioeventfd_set_disabled)(DeviceState *d, bool disabled);
+    /*
+     * Assigns/deassigns the ioeventfd backing for the transport on
+     * the device for queue number n. Returns an error value on
+     * failure.
+     */
+    int (*ioeventfd_assign)(DeviceState *d, EventNotifier *notifier,
+                            int n, bool assign);
+    /*
      * Does the transport have variable vring alignment?
      * (ie can it ever call virtio_queue_set_align()?)
      * Note that changing this will break migration for this transport.
@@ -111,4 +134,11 @@ static inline VirtIODevice *virtio_bus_get_device(VirtioBusState *bus)
     return (VirtIODevice *)qdev;
 }
 
+/* Start the ioeventfd. */
+void virtio_bus_start_ioeventfd(VirtioBusState *bus);
+/* Stop the ioeventfd. */
+void virtio_bus_stop_ioeventfd(VirtioBusState *bus);
+/* Switch from/to the generic ioeventfd handler */
+int virtio_bus_set_host_notifier(VirtioBusState *bus, int n, bool assign);
+
 #endif /* VIRTIO_BUS_H */
-- 
2.6.6

[Qemu-devel] [PATCH 2/6] virtio-bus: have callers tolerate new host notifier api

[Cornelia Huck]

Have vhost and dataplane use the new api for transports that
have been converted.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 hw/block/dataplane/virtio-blk.c | 14 +++++++++++---
 hw/scsi/virtio-scsi-dataplane.c | 20 +++++++++++++++-----
 hw/virtio/vhost.c               | 20 ++++++++++++++++----
 3 files changed, 42 insertions(+), 12 deletions(-)

diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
index 2073f9a..fdf5fd1 100644
--- a/hw/block/dataplane/virtio-blk.c
+++ b/hw/block/dataplane/virtio-blk.c
@@ -79,7 +79,8 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
     }
 
     /* Don't try if transport does not support notifiers. */
-    if (!k->set_guest_notifiers || !k->set_host_notifier) {
+    if (!k->set_guest_notifiers ||
+        (!k->set_host_notifier && !k->ioeventfd_started)) {
         error_setg(errp,
                    "device is incompatible with dataplane "
                    "(transport does not support notifiers)");
@@ -157,7 +158,10 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
     s->guest_notifier = virtio_queue_get_guest_notifier(s->vq);
 
     /* Set up virtqueue notify */
-    r = k->set_host_notifier(qbus->parent, 0, true);
+    r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), 0, true);
+    if (r == -ENOSYS) {
+        r = k->set_host_notifier(qbus->parent, 0, true);
+    }
     if (r != 0) {
         fprintf(stderr, "virtio-blk failed to set host notifier (%d)\n", r);
         goto fail_host_notifier;
@@ -193,6 +197,7 @@ void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s->vdev)));
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
     VirtIOBlock *vblk = VIRTIO_BLK(s->vdev);
+    int r;
 
     if (!vblk->dataplane_started || s->stopping) {
         return;
@@ -217,7 +222,10 @@ void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
 
     aio_context_release(s->ctx);
 
-    k->set_host_notifier(qbus->parent, 0, false);
+    r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), 0, false);
+    if (r == -ENOSYS) {
+        k->set_host_notifier(qbus->parent, 0, false);
+    }
 
     /* Clean up guest notifier (irq) */
     k->set_guest_notifiers(qbus->parent, 1, false);
diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
index 1a49f1e..b9a5716 100644
--- a/hw/scsi/virtio-scsi-dataplane.c
+++ b/hw/scsi/virtio-scsi-dataplane.c
@@ -31,7 +31,8 @@ void virtio_scsi_set_iothread(VirtIOSCSI *s, IOThread *iothread)
     s->ctx = iothread_get_aio_context(vs->conf.iothread);
 
     /* Don't try if transport does not support notifiers. */
-    if (!k->set_guest_notifiers || !k->set_host_notifier) {
+    if (!k->set_guest_notifiers ||
+        (!k->set_host_notifier && !k->ioeventfd_started)) {
         fprintf(stderr, "virtio-scsi: Failed to set iothread "
                    "(transport does not support notifiers)");
         exit(1);
@@ -73,7 +74,10 @@ static int virtio_scsi_vring_init(VirtIOSCSI *s, VirtQueue *vq, int n,
     int rc;
 
     /* Set up virtqueue notify */
-    rc = k->set_host_notifier(qbus->parent, n, true);
+    rc = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), n, true);
+    if (rc == -ENOSYS) {
+        rc = k->set_host_notifier(qbus->parent, n, true);
+    }
     if (rc != 0) {
         fprintf(stderr, "virtio-scsi: Failed to set host notifier (%d)\n",
                 rc);
@@ -159,7 +163,10 @@ fail_vrings:
     virtio_scsi_clear_aio(s);
     aio_context_release(s->ctx);
     for (i = 0; i < vs->conf.num_queues + 2; i++) {
-        k->set_host_notifier(qbus->parent, i, false);
+        rc = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
+        if (rc == -ENOSYS) {
+            k->set_host_notifier(qbus->parent, i, false);
+        }
     }
     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 fail_guest_notifiers:
@@ -174,7 +181,7 @@ void virtio_scsi_dataplane_stop(VirtIOSCSI *s)
     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
-    int i;
+    int i, rc;
 
     if (!s->dataplane_started || s->dataplane_stopping) {
         return;
@@ -198,7 +205,10 @@ void virtio_scsi_dataplane_stop(VirtIOSCSI *s)
     aio_context_release(s->ctx);
 
     for (i = 0; i < vs->conf.num_queues + 2; i++) {
-        k->set_host_notifier(qbus->parent, i, false);
+        rc = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
+        if (rc == -ENOSYS) {
+            k->set_host_notifier(qbus->parent, i, false);
+        }
     }
 
     /* Clean up guest notifier (irq) */
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 81cc5b0..bce1b6e 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -1110,14 +1110,18 @@ int vhost_dev_enable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev)
     VirtioBusState *vbus = VIRTIO_BUS(qbus);
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
     int i, r, e;
-    if (!k->set_host_notifier) {
+    if (!k->set_host_notifier || !k->ioeventfd_started) {
         fprintf(stderr, "binding does not support host notifiers\n");
         r = -ENOSYS;
         goto fail;
     }
 
     for (i = 0; i < hdev->nvqs; ++i) {
-        r = k->set_host_notifier(qbus->parent, hdev->vq_index + i, true);
+        r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i,
+                                         true);
+        if (r == -ENOSYS) {
+            r = k->set_host_notifier(qbus->parent, hdev->vq_index + i, true);
+        }
         if (r < 0) {
             fprintf(stderr, "vhost VQ %d notifier binding failed: %d\n", i, -r);
             goto fail_vq;
@@ -1127,7 +1131,11 @@ int vhost_dev_enable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev)
     return 0;
 fail_vq:
     while (--i >= 0) {
-        e = k->set_host_notifier(qbus->parent, hdev->vq_index + i, false);
+        e = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i,
+                                         false);
+        if (e == -ENOSYS) {
+            e = k->set_host_notifier(qbus->parent, hdev->vq_index + i, false);
+        }
         if (e < 0) {
             fprintf(stderr, "vhost VQ %d notifier cleanup error: %d\n", i, -r);
             fflush(stderr);
@@ -1151,7 +1159,11 @@ void vhost_dev_disable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev)
     int i, r;
 
     for (i = 0; i < hdev->nvqs; ++i) {
-        r = k->set_host_notifier(qbus->parent, hdev->vq_index + i, false);
+        r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i,
+                                         false);
+        if (r == -ENOSYS) {
+            r = k->set_host_notifier(qbus->parent, hdev->vq_index + i, false);
+        }
         if (r < 0) {
             fprintf(stderr, "vhost VQ %d notifier cleanup failed: %d\n", i, -r);
             fflush(stderr);
-- 
2.6.6

[Qemu-devel] [PATCH 3/6] virtio-ccw: convert to ioeventfd callbacks

[Cornelia Huck]

Use the new interface.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 hw/s390x/virtio-ccw.c | 133 +++++++++++++++++---------------------------------
 1 file changed, 45 insertions(+), 88 deletions(-)

diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
index 2b68e5e..2feb6dc 100644
--- a/hw/s390x/virtio-ccw.c
+++ b/hw/s390x/virtio-ccw.c
@@ -69,92 +69,58 @@ VirtIODevice *virtio_ccw_get_vdev(SubchDev *sch)
     return vdev;
 }
 
-static int virtio_ccw_set_guest2host_notifier(VirtioCcwDevice *dev, int n,
-                                              bool assign, bool set_handler)
+static void virtio_ccw_start_ioeventfd(VirtioCcwDevice *dev)
 {
-    VirtIODevice *vdev = virtio_bus_get_device(&dev->bus);
-    VirtQueue *vq = virtio_get_queue(vdev, n);
-    EventNotifier *notifier = virtio_queue_get_host_notifier(vq);
-    int r = 0;
-    SubchDev *sch = dev->sch;
-    uint32_t sch_id = (css_build_subchannel_id(sch) << 16) | sch->schid;
+    virtio_bus_start_ioeventfd(&dev->bus);
+}
 
-    if (assign) {
-        r = event_notifier_init(notifier, 1);
-        if (r < 0) {
-            error_report("%s: unable to init event notifier: %d", __func__, r);
-            return r;
-        }
-        virtio_queue_set_host_notifier_fd_handler(vq, true, set_handler);
-        r = s390_assign_subch_ioeventfd(notifier, sch_id, n, assign);
-        if (r < 0) {
-            error_report("%s: unable to assign ioeventfd: %d", __func__, r);
-            virtio_queue_set_host_notifier_fd_handler(vq, false, false);
-            event_notifier_cleanup(notifier);
-            return r;
-        }
-    } else {
-        virtio_queue_set_host_notifier_fd_handler(vq, false, false);
-        s390_assign_subch_ioeventfd(notifier, sch_id, n, assign);
-        event_notifier_cleanup(notifier);
-    }
-    return r;
+static void virtio_ccw_stop_ioeventfd(VirtioCcwDevice *dev)
+{
+    virtio_bus_stop_ioeventfd(&dev->bus);
 }
 
-static void virtio_ccw_start_ioeventfd(VirtioCcwDevice *dev)
+static bool virtio_ccw_ioeventfd_started(DeviceState *d)
 {
-    VirtIODevice *vdev;
-    int n, r;
+    VirtioCcwDevice *dev = VIRTIO_CCW_DEVICE(d);
 
-    if (!(dev->flags & VIRTIO_CCW_FLAG_USE_IOEVENTFD) ||
-        dev->ioeventfd_disabled ||
-        dev->ioeventfd_started) {
-        return;
-    }
-    vdev = virtio_bus_get_device(&dev->bus);
-    for (n = 0; n < VIRTIO_CCW_QUEUE_MAX; n++) {
-        if (!virtio_queue_get_num(vdev, n)) {
-            continue;
-        }
-        r = virtio_ccw_set_guest2host_notifier(dev, n, true, true);
-        if (r < 0) {
-            goto assign_error;
-        }
-    }
-    dev->ioeventfd_started = true;
-    return;
+    return dev->ioeventfd_started;
+}
 
-  assign_error:
-    while (--n >= 0) {
-        if (!virtio_queue_get_num(vdev, n)) {
-            continue;
-        }
-        r = virtio_ccw_set_guest2host_notifier(dev, n, false, false);
-        assert(r >= 0);
+static void virtio_ccw_ioeventfd_set_started(DeviceState *d, bool started,
+                                             bool err)
+{
+    VirtioCcwDevice *dev = VIRTIO_CCW_DEVICE(d);
+
+    dev->ioeventfd_started = started;
+    if (err) {
+        /* Disable ioeventfd for this device. */
+        dev->flags &= ~VIRTIO_CCW_FLAG_USE_IOEVENTFD;
     }
-    dev->ioeventfd_started = false;
-    /* Disable ioeventfd for this device. */
-    dev->flags &= ~VIRTIO_CCW_FLAG_USE_IOEVENTFD;
-    error_report("%s: failed. Fallback to userspace (slower).", __func__);
 }
 
-static void virtio_ccw_stop_ioeventfd(VirtioCcwDevice *dev)
+static bool virtio_ccw_ioeventfd_disabled(DeviceState *d)
 {
-    VirtIODevice *vdev;
-    int n, r;
+    VirtioCcwDevice *dev = VIRTIO_CCW_DEVICE(d);
 
-    if (!dev->ioeventfd_started) {
-        return;
-    }
-    vdev = virtio_bus_get_device(&dev->bus);
-    for (n = 0; n < VIRTIO_CCW_QUEUE_MAX; n++) {
-        if (!virtio_queue_get_num(vdev, n)) {
-            continue;
-        }
-        r = virtio_ccw_set_guest2host_notifier(dev, n, false, false);
-        assert(r >= 0);
-    }
-    dev->ioeventfd_started = false;
+    return dev->ioeventfd_disabled ||
+        !(dev->flags & VIRTIO_CCW_FLAG_USE_IOEVENTFD);
+}
+
+static void virtio_ccw_ioeventfd_set_disabled(DeviceState *d, bool disabled)
+{
+    VirtioCcwDevice *dev = VIRTIO_CCW_DEVICE(d);
+
+    dev->ioeventfd_disabled = disabled;
+}
+
+static int virtio_ccw_ioeventfd_assign(DeviceState *d, EventNotifier *notifier,
+                                       int n, bool assign)
+{
+    VirtioCcwDevice *dev = VIRTIO_CCW_DEVICE(d);
+    SubchDev *sch = dev->sch;
+    uint32_t sch_id = (css_build_subchannel_id(sch) << 16) | sch->schid;
+
+    return s390_assign_subch_ioeventfd(notifier, sch_id, n, assign);
 }
 
 VirtualCssBus *virtual_css_bus_init(void)
@@ -1195,19 +1161,6 @@ static bool virtio_ccw_query_guest_notifiers(DeviceState *d)
     return !!(dev->sch->curr_status.pmcw.flags & PMCW_FLAGS_MASK_ENA);
 }
 
-static int virtio_ccw_set_host_notifier(DeviceState *d, int n, bool assign)
-{
-    VirtioCcwDevice *dev = VIRTIO_CCW_DEVICE(d);
-
-    /* Stop using the generic ioeventfd, we are doing eventfd handling
-     * ourselves below */
-    dev->ioeventfd_disabled = assign;
-    if (assign) {
-        virtio_ccw_stop_ioeventfd(dev);
-    }
-    return virtio_ccw_set_guest2host_notifier(dev, n, assign, false);
-}
-
 static int virtio_ccw_get_mappings(VirtioCcwDevice *dev)
 {
     int r;
@@ -1836,7 +1789,6 @@ static void virtio_ccw_bus_class_init(ObjectClass *klass, void *data)
     k->notify = virtio_ccw_notify;
     k->vmstate_change = virtio_ccw_vmstate_change;
     k->query_guest_notifiers = virtio_ccw_query_guest_notifiers;
-    k->set_host_notifier = virtio_ccw_set_host_notifier;
     k->set_guest_notifiers = virtio_ccw_set_guest_notifiers;
     k->save_queue = virtio_ccw_save_queue;
     k->load_queue = virtio_ccw_load_queue;
@@ -1845,6 +1797,11 @@ static void virtio_ccw_bus_class_init(ObjectClass *klass, void *data)
     k->device_plugged = virtio_ccw_device_plugged;
     k->post_plugged = virtio_ccw_post_plugged;
     k->device_unplugged = virtio_ccw_device_unplugged;
+    k->ioeventfd_started = virtio_ccw_ioeventfd_started;
+    k->ioeventfd_set_started = virtio_ccw_ioeventfd_set_started;
+    k->ioeventfd_disabled = virtio_ccw_ioeventfd_disabled;
+    k->ioeventfd_set_disabled = virtio_ccw_ioeventfd_set_disabled;
+    k->ioeventfd_assign = virtio_ccw_ioeventfd_assign;
 }
 
 static const TypeInfo virtio_ccw_bus_info = {
-- 
2.6.6

[Qemu-devel] [PATCH 4/6] virtio-pci: convert to ioeventfd callbacks

[Cornelia Huck]

Convert to new interface.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 hw/virtio/virtio-pci.c | 124 ++++++++++++++++---------------------------------
 1 file changed, 41 insertions(+), 83 deletions(-)

diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index bfedbbf..ca2003c 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -262,14 +262,44 @@ static int virtio_pci_load_queue(DeviceState *d, int n, QEMUFile *f)
     return 0;
 }
 
+static bool virtio_pci_ioeventfd_started(DeviceState *d)
+{
+    VirtIOPCIProxy *proxy = to_virtio_pci_proxy(d);
+
+    return proxy->ioeventfd_started;
+}
+
+static void virtio_pci_ioeventfd_set_started(DeviceState *d, bool started,
+                                             bool err)
+{
+    VirtIOPCIProxy *proxy = to_virtio_pci_proxy(d);
+
+    proxy->ioeventfd_started = started;
+}
+
+static bool virtio_pci_ioeventfd_disabled(DeviceState *d)
+{
+    VirtIOPCIProxy *proxy = to_virtio_pci_proxy(d);
+
+    return proxy->ioeventfd_disabled ||
+        !(proxy->flags & VIRTIO_PCI_FLAG_USE_IOEVENTFD);
+}
+
+static void virtio_pci_ioeventfd_set_disabled(DeviceState *d, bool disabled)
+{
+    VirtIOPCIProxy *proxy = to_virtio_pci_proxy(d);
+
+    proxy->ioeventfd_disabled = disabled;
+}
+
 #define QEMU_VIRTIO_PCI_QUEUE_MEM_MULT 0x1000
 
-static int virtio_pci_set_host_notifier_internal(VirtIOPCIProxy *proxy,
-                                                 int n, bool assign, bool set_handler)
+static int virtio_pci_ioeventfd_assign(DeviceState *d, EventNotifier *notifier,
+                                       int n, bool assign)
 {
+    VirtIOPCIProxy *proxy = to_virtio_pci_proxy(d);
     VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
     VirtQueue *vq = virtio_get_queue(vdev, n);
-    EventNotifier *notifier = virtio_queue_get_host_notifier(vq);
     bool legacy = !(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_LEGACY);
     bool modern = !(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_MODERN);
     bool fast_mmio = kvm_ioeventfd_any_length_enabled();
@@ -280,16 +310,8 @@ static int virtio_pci_set_host_notifier_internal(VirtIOPCIProxy *proxy,
     hwaddr modern_addr = QEMU_VIRTIO_PCI_QUEUE_MEM_MULT *
                          virtio_get_queue_index(vq);
     hwaddr legacy_addr = VIRTIO_PCI_QUEUE_NOTIFY;
-    int r = 0;
 
     if (assign) {
-        r = event_notifier_init(notifier, 1);
-        if (r < 0) {
-            error_report("%s: unable to init event notifier: %d",
-                         __func__, r);
-            return r;
-        }
-        virtio_queue_set_host_notifier_fd_handler(vq, true, set_handler);
         if (modern) {
             if (fast_mmio) {
                 memory_region_add_eventfd(modern_mr, modern_addr, 0,
@@ -325,68 +347,18 @@ static int virtio_pci_set_host_notifier_internal(VirtIOPCIProxy *proxy,
             memory_region_del_eventfd(legacy_mr, legacy_addr, 2,
                                       true, n, notifier);
         }
-        virtio_queue_set_host_notifier_fd_handler(vq, false, false);
-        event_notifier_cleanup(notifier);
     }
-    return r;
+    return 0;
 }
 
 static void virtio_pci_start_ioeventfd(VirtIOPCIProxy *proxy)
 {
-    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
-    int n, r;
-
-    if (!(proxy->flags & VIRTIO_PCI_FLAG_USE_IOEVENTFD) ||
-        proxy->ioeventfd_disabled ||
-        proxy->ioeventfd_started) {
-        return;
-    }
-
-    for (n = 0; n < VIRTIO_QUEUE_MAX; n++) {
-        if (!virtio_queue_get_num(vdev, n)) {
-            continue;
-        }
-
-        r = virtio_pci_set_host_notifier_internal(proxy, n, true, true);
-        if (r < 0) {
-            goto assign_error;
-        }
-    }
-    proxy->ioeventfd_started = true;
-    return;
-
-assign_error:
-    while (--n >= 0) {
-        if (!virtio_queue_get_num(vdev, n)) {
-            continue;
-        }
-
-        r = virtio_pci_set_host_notifier_internal(proxy, n, false, false);
-        assert(r >= 0);
-    }
-    proxy->ioeventfd_started = false;
-    error_report("%s: failed. Fallback to a userspace (slower).", __func__);
+    virtio_bus_start_ioeventfd(&proxy->bus);
 }
 
 static void virtio_pci_stop_ioeventfd(VirtIOPCIProxy *proxy)
 {
-    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
-    int r;
-    int n;
-
-    if (!proxy->ioeventfd_started) {
-        return;
-    }
-
-    for (n = 0; n < VIRTIO_QUEUE_MAX; n++) {
-        if (!virtio_queue_get_num(vdev, n)) {
-            continue;
-        }
-
-        r = virtio_pci_set_host_notifier_internal(proxy, n, false, false);
-        assert(r >= 0);
-    }
-    proxy->ioeventfd_started = false;
+    virtio_bus_stop_ioeventfd(&proxy->bus);
 }
 
 static void virtio_ioport_write(void *opaque, uint32_t addr, uint32_t val)
@@ -1112,24 +1084,6 @@ assign_error:
     return r;
 }
 
-static int virtio_pci_set_host_notifier(DeviceState *d, int n, bool assign)
-{
-    VirtIOPCIProxy *proxy = to_virtio_pci_proxy(d);
-
-    /* Stop using ioeventfd for virtqueue kick if the device starts using host
-     * notifiers.  This makes it easy to avoid stepping on each others' toes.
-     */
-    proxy->ioeventfd_disabled = assign;
-    if (assign) {
-        virtio_pci_stop_ioeventfd(proxy);
-    }
-    /* We don't need to start here: it's not needed because backend
-     * currently only stops on status change away from ok,
-     * reset, vmstop and such. If we do add code to start here,
-     * need to check vmstate, device state etc. */
-    return virtio_pci_set_host_notifier_internal(proxy, n, assign, false);
-}
-
 static void virtio_pci_vmstate_change(DeviceState *d, bool running)
 {
     VirtIOPCIProxy *proxy = to_virtio_pci_proxy(d);
@@ -2490,12 +2444,16 @@ static void virtio_pci_bus_class_init(ObjectClass *klass, void *data)
     k->load_extra_state = virtio_pci_load_extra_state;
     k->has_extra_state = virtio_pci_has_extra_state;
     k->query_guest_notifiers = virtio_pci_query_guest_notifiers;
-    k->set_host_notifier = virtio_pci_set_host_notifier;
     k->set_guest_notifiers = virtio_pci_set_guest_notifiers;
     k->vmstate_change = virtio_pci_vmstate_change;
     k->device_plugged = virtio_pci_device_plugged;
     k->device_unplugged = virtio_pci_device_unplugged;
     k->query_nvectors = virtio_pci_query_nvectors;
+    k->ioeventfd_started = virtio_pci_ioeventfd_started;
+    k->ioeventfd_set_started = virtio_pci_ioeventfd_set_started;
+    k->ioeventfd_disabled = virtio_pci_ioeventfd_disabled;
+    k->ioeventfd_set_disabled = virtio_pci_ioeventfd_set_disabled;
+    k->ioeventfd_assign = virtio_pci_ioeventfd_assign;
 }
 
 static const TypeInfo virtio_pci_bus_info = {
-- 
2.6.6

[Qemu-devel] [PATCH 5/6] virtio-mmio: convert to ioeventfd callbacks

[Cornelia Huck]

Convert to the new interface.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 hw/virtio/virtio-mmio.c | 128 ++++++++++++++++--------------------------------
 1 file changed, 41 insertions(+), 87 deletions(-)

diff --git a/hw/virtio/virtio-mmio.c b/hw/virtio/virtio-mmio.c
index d4cd91f..eb84b74 100644
--- a/hw/virtio/virtio-mmio.c
+++ b/hw/virtio/virtio-mmio.c
@@ -93,90 +93,59 @@ typedef struct {
     bool ioeventfd_started;
 } VirtIOMMIOProxy;
 
-static int virtio_mmio_set_host_notifier_internal(VirtIOMMIOProxy *proxy,
-                                                  int n, bool assign,
-                                                  bool set_handler)
+static bool virtio_mmio_ioeventfd_started(DeviceState *d)
 {
-    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
-    VirtQueue *vq = virtio_get_queue(vdev, n);
-    EventNotifier *notifier = virtio_queue_get_host_notifier(vq);
-    int r = 0;
+    VirtIOMMIOProxy *proxy = VIRTIO_MMIO(d);
 
-    if (assign) {
-        r = event_notifier_init(notifier, 1);
-        if (r < 0) {
-            error_report("%s: unable to init event notifier: %d",
-                         __func__, r);
-            return r;
-        }
-        virtio_queue_set_host_notifier_fd_handler(vq, true, set_handler);
-        memory_region_add_eventfd(&proxy->iomem, VIRTIO_MMIO_QUEUENOTIFY, 4,
-                                  true, n, notifier);
-    } else {
-        memory_region_del_eventfd(&proxy->iomem, VIRTIO_MMIO_QUEUENOTIFY, 4,
-                                  true, n, notifier);
-        virtio_queue_set_host_notifier_fd_handler(vq, false, false);
-        event_notifier_cleanup(notifier);
-    }
-    return r;
+    return proxy->ioeventfd_started;
 }
 
-static void virtio_mmio_start_ioeventfd(VirtIOMMIOProxy *proxy)
+static void virtio_mmio_ioeventfd_set_started(DeviceState *d, bool started,
+                                              bool err)
 {
-    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
-    int n, r;
+    VirtIOMMIOProxy *proxy = VIRTIO_MMIO(d);
 
-    if (!kvm_eventfds_enabled() ||
-        proxy->ioeventfd_disabled ||
-        proxy->ioeventfd_started) {
-        return;
-    }
+    proxy->ioeventfd_started = started;
+}
 
-    for (n = 0; n < VIRTIO_QUEUE_MAX; n++) {
-        if (!virtio_queue_get_num(vdev, n)) {
-            continue;
-        }
+static bool virtio_mmio_ioeventfd_disabled(DeviceState *d)
+{
+    VirtIOMMIOProxy *proxy = VIRTIO_MMIO(d);
 
-        r = virtio_mmio_set_host_notifier_internal(proxy, n, true, true);
-        if (r < 0) {
-            goto assign_error;
-        }
-    }
-    proxy->ioeventfd_started = true;
-    return;
+    return !kvm_eventfds_enabled() || proxy->ioeventfd_disabled;
+}
 
-assign_error:
-    while (--n >= 0) {
-        if (!virtio_queue_get_num(vdev, n)) {
-            continue;
-        }
+static void virtio_mmio_ioeventfd_set_disabled(DeviceState *d, bool disabled)
+{
+    VirtIOMMIOProxy *proxy = VIRTIO_MMIO(d);
 
-        r = virtio_mmio_set_host_notifier_internal(proxy, n, false, false);
-        assert(r >= 0);
-    }
-    proxy->ioeventfd_started = false;
-    error_report("%s: failed. Fallback to a userspace (slower).", __func__);
+    proxy->ioeventfd_disabled = disabled;
 }
 
-static void virtio_mmio_stop_ioeventfd(VirtIOMMIOProxy *proxy)
+static int virtio_mmio_ioeventfd_assign(DeviceState *d,
+                                        EventNotifier *notifier,
+                                        int n, bool assign)
 {
-    int r;
-    int n;
-    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
+    VirtIOMMIOProxy *proxy = VIRTIO_MMIO(d);
 
-    if (!proxy->ioeventfd_started) {
-        return;
+    if (assign) {
+        memory_region_add_eventfd(&proxy->iomem, VIRTIO_MMIO_QUEUENOTIFY, 4,
+                                  true, n, notifier);
+    } else {
+        memory_region_del_eventfd(&proxy->iomem, VIRTIO_MMIO_QUEUENOTIFY, 4,
+                                  true, n, notifier);
     }
+    return 0;
+}
 
-    for (n = 0; n < VIRTIO_QUEUE_MAX; n++) {
-        if (!virtio_queue_get_num(vdev, n)) {
-            continue;
-        }
+static void virtio_mmio_start_ioeventfd(VirtIOMMIOProxy *proxy)
+{
+    virtio_bus_start_ioeventfd(&proxy->bus);
+}
 
-        r = virtio_mmio_set_host_notifier_internal(proxy, n, false, false);
-        assert(r >= 0);
-    }
-    proxy->ioeventfd_started = false;
+static void virtio_mmio_stop_ioeventfd(VirtIOMMIOProxy *proxy)
+{
+    virtio_bus_stop_ioeventfd(&proxy->bus);
 }
 
 static uint64_t virtio_mmio_read(void *opaque, hwaddr offset, unsigned size)
@@ -498,25 +467,6 @@ assign_error:
     return r;
 }
 
-static int virtio_mmio_set_host_notifier(DeviceState *opaque, int n,
-                                         bool assign)
-{
-    VirtIOMMIOProxy *proxy = VIRTIO_MMIO(opaque);
-
-    /* Stop using ioeventfd for virtqueue kick if the device starts using host
-     * notifiers.  This makes it easy to avoid stepping on each others' toes.
-     */
-    proxy->ioeventfd_disabled = assign;
-    if (assign) {
-        virtio_mmio_stop_ioeventfd(proxy);
-    }
-    /* We don't need to start here: it's not needed because backend
-     * currently only stops on status change away from ok,
-     * reset, vmstop and such. If we do add code to start here,
-     * need to check vmstate, device state etc. */
-    return virtio_mmio_set_host_notifier_internal(proxy, n, assign, false);
-}
-
 /* virtio-mmio device */
 
 static void virtio_mmio_realizefn(DeviceState *d, Error **errp)
@@ -558,8 +508,12 @@ static void virtio_mmio_bus_class_init(ObjectClass *klass, void *data)
     k->notify = virtio_mmio_update_irq;
     k->save_config = virtio_mmio_save_config;
     k->load_config = virtio_mmio_load_config;
-    k->set_host_notifier = virtio_mmio_set_host_notifier;
     k->set_guest_notifiers = virtio_mmio_set_guest_notifiers;
+    k->ioeventfd_started = virtio_mmio_ioeventfd_started;
+    k->ioeventfd_set_started = virtio_mmio_ioeventfd_set_started;
+    k->ioeventfd_disabled = virtio_mmio_ioeventfd_disabled;
+    k->ioeventfd_set_disabled = virtio_mmio_ioeventfd_set_disabled;
+    k->ioeventfd_assign = virtio_mmio_ioeventfd_assign;
     k->has_variable_vring_alignment = true;
     bus_class->max_dev = 1;
 }
-- 
2.6.6

[Qemu-devel] [PATCH 6/6] virtio-bus: remove old set_host_notifier callback

[Cornelia Huck]

All users have been converted to the new ioevent callbacks.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 hw/block/dataplane/virtio-blk.c | 12 ++----------
 hw/scsi/virtio-scsi-dataplane.c | 19 ++++---------------
 hw/virtio/vhost.c               | 13 +------------
 include/hw/virtio/virtio-bus.h  |  1 -
 4 files changed, 7 insertions(+), 38 deletions(-)

diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
index fdf5fd1..2041b04 100644
--- a/hw/block/dataplane/virtio-blk.c
+++ b/hw/block/dataplane/virtio-blk.c
@@ -79,8 +79,7 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
     }
 
     /* Don't try if transport does not support notifiers. */
-    if (!k->set_guest_notifiers ||
-        (!k->set_host_notifier && !k->ioeventfd_started)) {
+    if (!k->set_guest_notifiers || !k->ioeventfd_started) {
         error_setg(errp,
                    "device is incompatible with dataplane "
                    "(transport does not support notifiers)");
@@ -159,9 +158,6 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
 
     /* Set up virtqueue notify */
     r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), 0, true);
-    if (r == -ENOSYS) {
-        r = k->set_host_notifier(qbus->parent, 0, true);
-    }
     if (r != 0) {
         fprintf(stderr, "virtio-blk failed to set host notifier (%d)\n", r);
         goto fail_host_notifier;
@@ -197,7 +193,6 @@ void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s->vdev)));
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
     VirtIOBlock *vblk = VIRTIO_BLK(s->vdev);
-    int r;
 
     if (!vblk->dataplane_started || s->stopping) {
         return;
@@ -222,10 +217,7 @@ void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
 
     aio_context_release(s->ctx);
 
-    r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), 0, false);
-    if (r == -ENOSYS) {
-        k->set_host_notifier(qbus->parent, 0, false);
-    }
+    virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), 0, false);
 
     /* Clean up guest notifier (irq) */
     k->set_guest_notifiers(qbus->parent, 1, false);
diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
index b9a5716..18ced31 100644
--- a/hw/scsi/virtio-scsi-dataplane.c
+++ b/hw/scsi/virtio-scsi-dataplane.c
@@ -31,8 +31,7 @@ void virtio_scsi_set_iothread(VirtIOSCSI *s, IOThread *iothread)
     s->ctx = iothread_get_aio_context(vs->conf.iothread);
 
     /* Don't try if transport does not support notifiers. */
-    if (!k->set_guest_notifiers ||
-        (!k->set_host_notifier && !k->ioeventfd_started)) {
+    if (!k->set_guest_notifiers || !k->ioeventfd_started) {
         fprintf(stderr, "virtio-scsi: Failed to set iothread "
                    "(transport does not support notifiers)");
         exit(1);
@@ -70,14 +69,10 @@ static int virtio_scsi_vring_init(VirtIOSCSI *s, VirtQueue *vq, int n,
                                   void (*fn)(VirtIODevice *vdev, VirtQueue *vq))
 {
     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
     int rc;
 
     /* Set up virtqueue notify */
     rc = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), n, true);
-    if (rc == -ENOSYS) {
-        rc = k->set_host_notifier(qbus->parent, n, true);
-    }
     if (rc != 0) {
         fprintf(stderr, "virtio-scsi: Failed to set host notifier (%d)\n",
                 rc);
@@ -163,10 +158,7 @@ fail_vrings:
     virtio_scsi_clear_aio(s);
     aio_context_release(s->ctx);
     for (i = 0; i < vs->conf.num_queues + 2; i++) {
-        rc = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
-        if (rc == -ENOSYS) {
-            k->set_host_notifier(qbus->parent, i, false);
-        }
+        virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
     }
     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
 fail_guest_notifiers:
@@ -181,7 +173,7 @@ void virtio_scsi_dataplane_stop(VirtIOSCSI *s)
     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
-    int i, rc;
+    int i;
 
     if (!s->dataplane_started || s->dataplane_stopping) {
         return;
@@ -205,10 +197,7 @@ void virtio_scsi_dataplane_stop(VirtIOSCSI *s)
     aio_context_release(s->ctx);
 
     for (i = 0; i < vs->conf.num_queues + 2; i++) {
-        rc = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
-        if (rc == -ENOSYS) {
-            k->set_host_notifier(qbus->parent, i, false);
-        }
+        virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
     }
 
     /* Clean up guest notifier (irq) */
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index bce1b6e..a01394d 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -1110,7 +1110,7 @@ int vhost_dev_enable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev)
     VirtioBusState *vbus = VIRTIO_BUS(qbus);
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
     int i, r, e;
-    if (!k->set_host_notifier || !k->ioeventfd_started) {
+    if (!k->ioeventfd_started) {
         fprintf(stderr, "binding does not support host notifiers\n");
         r = -ENOSYS;
         goto fail;
@@ -1119,9 +1119,6 @@ int vhost_dev_enable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev)
     for (i = 0; i < hdev->nvqs; ++i) {
         r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i,
                                          true);
-        if (r == -ENOSYS) {
-            r = k->set_host_notifier(qbus->parent, hdev->vq_index + i, true);
-        }
         if (r < 0) {
             fprintf(stderr, "vhost VQ %d notifier binding failed: %d\n", i, -r);
             goto fail_vq;
@@ -1133,9 +1130,6 @@ fail_vq:
     while (--i >= 0) {
         e = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i,
                                          false);
-        if (e == -ENOSYS) {
-            e = k->set_host_notifier(qbus->parent, hdev->vq_index + i, false);
-        }
         if (e < 0) {
             fprintf(stderr, "vhost VQ %d notifier cleanup error: %d\n", i, -r);
             fflush(stderr);
@@ -1154,16 +1148,11 @@ fail:
 void vhost_dev_disable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev)
 {
     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
-    VirtioBusState *vbus = VIRTIO_BUS(qbus);
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
     int i, r;
 
     for (i = 0; i < hdev->nvqs; ++i) {
         r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i,
                                          false);
-        if (r == -ENOSYS) {
-            r = k->set_host_notifier(qbus->parent, hdev->vq_index + i, false);
-        }
         if (r < 0) {
             fprintf(stderr, "vhost VQ %d notifier cleanup failed: %d\n", i, -r);
             fflush(stderr);
diff --git a/include/hw/virtio/virtio-bus.h b/include/hw/virtio/virtio-bus.h
index 9637f80..f3e5ef3 100644
--- a/include/hw/virtio/virtio-bus.h
+++ b/include/hw/virtio/virtio-bus.h
@@ -52,7 +52,6 @@ typedef struct VirtioBusClass {
     bool (*has_extra_state)(DeviceState *d);
     bool (*query_guest_notifiers)(DeviceState *d);
     int (*set_guest_notifiers)(DeviceState *d, int nvqs, bool assign);
-    int (*set_host_notifier)(DeviceState *d, int n, bool assigned);
     void (*vmstate_change)(DeviceState *d, bool running);
     /*
      * transport independent init function.
-- 
2.6.6

Re: [Qemu-devel] [RESEND] [PATCH 0/6] virtio: refactor host notifiers

[Fam Zheng]

On Fri, 06/10 11:04, Cornelia Huck wrote:
> Hi,
> 
> this is a resend of the host notifier refactoring I last sent out
> on 2016/04/25. Just rebased on current master and pushed out to
> github.com/cohuck/qemu host-notifier-refactor.
> 
> Blurb from the last posting follows:
> 
> This still fixes an issue where we have no ioeventfd for a short
> time, but it does not break our necks any more with the recent
> fixes. Still, I think this is a net win, especially considering
> we remove a lot of similar code from the individual transports.

Agreed. And the changes look good to me, thanks.

Reviewed-by: Fam Zheng <famz@redhat.com>

> 
> Cornelia Huck (6):
>   virtio-bus: common ioeventfd infrastructure
>   virtio-bus: have callers tolerate new host notifier api
>   virtio-ccw: convert to ioeventfd callbacks
>   virtio-pci: convert to ioeventfd callbacks
>   virtio-mmio: convert to ioeventfd callbacks
>   virtio-bus: remove old set_host_notifier callback
> 
>  hw/block/dataplane/virtio-blk.c |   6 +-
>  hw/s390x/virtio-ccw.c           | 133 ++++++++++++++--------------------------
>  hw/scsi/virtio-scsi-dataplane.c |   9 ++-
>  hw/virtio/vhost.c               |  13 ++--
>  hw/virtio/virtio-bus.c          | 132 +++++++++++++++++++++++++++++++++++++++
>  hw/virtio/virtio-mmio.c         | 128 +++++++++++++-------------------------
>  hw/virtio/virtio-pci.c          | 124 +++++++++++++------------------------
>  include/hw/virtio/virtio-bus.h  |  31 +++++++++-
>  8 files changed, 303 insertions(+), 273 deletions(-)
> 
> -- 
> 2.6.6
> 

Re: [Qemu-devel] [RESEND] [PATCH 0/6] virtio: refactor host notifiers

[Stefan Hajnoczi]

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On Fri, Jun 10, 2016 at 11:04:08AM +0200, Cornelia Huck wrote:
> Hi,
> 
> this is a resend of the host notifier refactoring I last sent out
> on 2016/04/25. Just rebased on current master and pushed out to
> github.com/cohuck/qemu host-notifier-refactor.
> 
> Blurb from the last posting follows:
> 
> This still fixes an issue where we have no ioeventfd for a short
> time, but it does not break our necks any more with the recent
> fixes. Still, I think this is a net win, especially considering
> we remove a lot of similar code from the individual transports.
> 
> Cornelia Huck (6):
>   virtio-bus: common ioeventfd infrastructure
>   virtio-bus: have callers tolerate new host notifier api
>   virtio-ccw: convert to ioeventfd callbacks
>   virtio-pci: convert to ioeventfd callbacks
>   virtio-mmio: convert to ioeventfd callbacks
>   virtio-bus: remove old set_host_notifier callback
> 
>  hw/block/dataplane/virtio-blk.c |   6 +-

Reviewed just the small dataplane/virtio-blk.c portion but agree with
the series in general:

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

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