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[RFC 3/8] virtio: Add API to batch set host notifiers
From: |
Greg Kurz |
Subject: |
[RFC 3/8] virtio: Add API to batch set host notifiers |
Date: |
Thu, 25 Mar 2021 16:07:30 +0100 |
Introduce VirtioBusClass methods to begin and commit a transaction
of setting/unsetting host notifiers. These handlers will be implemented
by virtio-pci to batch addition and deletion of ioeventfds for multiqueue
devices like virtio-scsi-pci or virtio-blk-pci.
Convert virtio_bus_set_host_notifiers() to use these handlers. Note that
virtio_bus_cleanup_host_notifier() closes eventfds, which could still be
passed to the KVM_IOEVENTFD ioctl() when the transaction ends and fail
with EBADF. The cleanup of the host notifiers is thus pushed to a
separate loop in virtio_bus_unset_and_cleanup_host_notifiers(), after
transaction commit.
Signed-off-by: Greg Kurz <groug@kaod.org>
---
include/hw/virtio/virtio-bus.h | 4 ++++
hw/virtio/virtio-bus.c | 34 ++++++++++++++++++++++++++++++++++
2 files changed, 38 insertions(+)
diff --git a/include/hw/virtio/virtio-bus.h b/include/hw/virtio/virtio-bus.h
index 6d1e4ee3e886..99704b2c090a 100644
--- a/include/hw/virtio/virtio-bus.h
+++ b/include/hw/virtio/virtio-bus.h
@@ -82,6 +82,10 @@ struct VirtioBusClass {
*/
int (*ioeventfd_assign)(DeviceState *d, EventNotifier *notifier,
int n, bool assign);
+
+ void (*ioeventfd_assign_begin)(DeviceState *d);
+ void (*ioeventfd_assign_commit)(DeviceState *d);
+
/*
* Whether queue number n is enabled.
*/
diff --git a/hw/virtio/virtio-bus.c b/hw/virtio/virtio-bus.c
index c9e7cdb5c161..156484c4ca14 100644
--- a/hw/virtio/virtio-bus.c
+++ b/hw/virtio/virtio-bus.c
@@ -295,6 +295,28 @@ int virtio_bus_set_host_notifier(VirtioBusState *bus, int
n, bool assign)
return r;
}
+static void virtio_bus_set_host_notifier_begin(VirtioBusState *bus)
+{
+ VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
+ DeviceState *proxy = DEVICE(BUS(bus)->parent);
+
+ if (k->ioeventfd_assign_begin) {
+ assert(k->ioeventfd_assign_commit);
+ k->ioeventfd_assign_begin(proxy);
+ }
+}
+
+static void virtio_bus_set_host_notifier_commit(VirtioBusState *bus)
+{
+ VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
+ DeviceState *proxy = DEVICE(BUS(bus)->parent);
+
+ if (k->ioeventfd_assign_commit) {
+ assert(k->ioeventfd_assign_begin);
+ k->ioeventfd_assign_commit(proxy);
+ }
+}
+
void virtio_bus_cleanup_host_notifier(VirtioBusState *bus, int n)
{
VirtIODevice *vdev = virtio_bus_get_device(bus);
@@ -308,6 +330,7 @@ void virtio_bus_cleanup_host_notifier(VirtioBusState *bus,
int n)
event_notifier_cleanup(notifier);
}
+/* virtio_bus_set_host_notifier_begin() must have been called */
static void virtio_bus_unset_and_cleanup_host_notifiers(VirtioBusState *bus,
int nvqs, int n_offset)
{
@@ -315,6 +338,10 @@ static void
virtio_bus_unset_and_cleanup_host_notifiers(VirtioBusState *bus,
for (i = 0; i < nvqs; i++) {
virtio_bus_set_host_notifier(bus, i + n_offset, false);
+ }
+ /* Let address_space_update_ioeventfds() run before closing ioeventfds */
+ virtio_bus_set_host_notifier_commit(bus);
+ for (i = 0; i < nvqs; i++) {
virtio_bus_cleanup_host_notifier(bus, i + n_offset);
}
}
@@ -327,17 +354,24 @@ int virtio_bus_set_host_notifiers(VirtioBusState *bus,
int nvqs, int n_offset,
int rc;
if (assign) {
+ virtio_bus_set_host_notifier_begin(bus);
+
for (i = 0; i < nvqs; i++) {
rc = virtio_bus_set_host_notifier(bus, i + n_offset, true);
if (rc != 0) {
warn_report_once("%s: Failed to set host notifier (%s).\n",
vdev->name, strerror(-rc));
+ /* This also calls virtio_bus_set_host_notifier_commit() */
virtio_bus_unset_and_cleanup_host_notifiers(bus, i, n_offset);
return rc;
}
}
+
+ virtio_bus_set_host_notifier_commit(bus);
} else {
+ virtio_bus_set_host_notifier_begin(bus);
+ /* This also calls virtio_bus_set_host_notifier_commit() */
virtio_bus_unset_and_cleanup_host_notifiers(bus, nvqs, n_offset);
}
--
2.26.3
- [RFC 0/8] virtio: Improve boot time of virtio-scsi-pci and virtio-blk-pci, Greg Kurz, 2021/03/25
- [RFC 2/8] virtio: Introduce virtio_bus_set_host_notifiers(), Greg Kurz, 2021/03/25
- [RFC 3/8] virtio: Add API to batch set host notifiers,
Greg Kurz <=
- Re: [RFC 3/8] virtio: Add API to batch set host notifiers, Stefan Hajnoczi, 2021/03/29
- Re: [RFC 3/8] virtio: Add API to batch set host notifiers, Greg Kurz, 2021/03/30
- Re: [RFC 3/8] virtio: Add API to batch set host notifiers, Stefan Hajnoczi, 2021/03/30
- Re: [RFC 3/8] virtio: Add API to batch set host notifiers, Greg Kurz, 2021/03/30
- Re: [RFC 3/8] virtio: Add API to batch set host notifiers, Stefan Hajnoczi, 2021/03/31
- Re: [RFC 3/8] virtio: Add API to batch set host notifiers, Greg Kurz, 2021/03/31
[RFC 4/8] virtio-pci: Batch add/del ioeventfds in a single MR transaction, Greg Kurz, 2021/03/25
[RFC 5/8] virtio-blk: Fix rollback path in virtio_blk_data_plane_start(), Greg Kurz, 2021/03/25