[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [RFC 3/8] virtio: Add API to batch set host notifiers
From: |
Stefan Hajnoczi |
Subject: |
Re: [RFC 3/8] virtio: Add API to batch set host notifiers |
Date: |
Mon, 29 Mar 2021 18:10:57 +0100 |
On Thu, Mar 25, 2021 at 04:07:30PM +0100, Greg Kurz wrote:
> 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);
Please add doc comments for these new functions.
> +
> /*
> * 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 */
assert(memory_region_transaction_depth == 0)?
> + 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
>
signature.asc
Description: PGP signature
- [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, 2021/03/25
- Re: [RFC 3/8] virtio: Add API to batch set host notifiers,
Stefan Hajnoczi <=
- 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