[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [RFC v2 11/13] vdpa: add vdpa net migration state notifier
From: |
Eugenio Perez Martin |
Subject: |
Re: [RFC v2 11/13] vdpa: add vdpa net migration state notifier |
Date: |
Fri, 13 Jan 2023 10:00:08 +0100 |
On Fri, Jan 13, 2023 at 5:55 AM Jason Wang <jasowang@redhat.com> wrote:
>
> On Fri, Jan 13, 2023 at 1:25 AM Eugenio Pérez <eperezma@redhat.com> wrote:
> >
> > This allows net to restart the device backend to configure SVQ on it.
> >
> > Ideally, these changes should not be net specific. However, the vdpa net
> > backend is the one with enough knowledge to configure everything because
> > of some reasons:
> > * Queues might need to be shadowed or not depending on its kind (control
> > vs data).
> > * Queues need to share the same map translations (iova tree).
> >
> > Because of that it is cleaner to restart the whole net backend and
> > configure again as expected, similar to how vhost-kernel moves between
> > userspace and passthrough.
> >
> > If more kinds of devices need dynamic switching to SVQ we can create a
> > callback struct like VhostOps and move most of the code there.
> > VhostOps cannot be reused since all vdpa backend share them, and to
> > personalize just for networking would be too heavy.
> >
> > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > ---
> > net/vhost-vdpa.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 84 insertions(+)
> >
> > diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> > index 5d7ad6e4d7..f38532b1df 100644
> > --- a/net/vhost-vdpa.c
> > +++ b/net/vhost-vdpa.c
> > @@ -26,6 +26,8 @@
> > #include <err.h>
> > #include "standard-headers/linux/virtio_net.h"
> > #include "monitor/monitor.h"
> > +#include "migration/migration.h"
> > +#include "migration/misc.h"
> > #include "migration/blocker.h"
> > #include "hw/virtio/vhost.h"
> >
> > @@ -33,6 +35,7 @@
> > typedef struct VhostVDPAState {
> > NetClientState nc;
> > struct vhost_vdpa vhost_vdpa;
> > + Notifier migration_state;
> > Error *migration_blocker;
> > VHostNetState *vhost_net;
> >
> > @@ -243,10 +246,86 @@ static VhostVDPAState
> > *vhost_vdpa_net_first_nc_vdpa(VhostVDPAState *s)
> > return DO_UPCAST(VhostVDPAState, nc, nc0);
> > }
> >
> > +static void vhost_vdpa_net_log_global_enable(VhostVDPAState *s, bool
> > enable)
> > +{
> > + struct vhost_vdpa *v = &s->vhost_vdpa;
> > + VirtIONet *n;
> > + VirtIODevice *vdev;
> > + int data_queue_pairs, cvq, r;
> > + NetClientState *peer;
> > +
> > + /* We are only called on the first data vqs and only if x-svq is not
> > set */
> > + if (s->vhost_vdpa.shadow_vqs_enabled == enable) {
> > + return;
> > + }
> > +
> > + vdev = v->dev->vdev;
> > + n = VIRTIO_NET(vdev);
> > + if (!n->vhost_started) {
> > + return;
> > + }
> > +
> > + if (enable) {
> > + ioctl(v->device_fd, VHOST_VDPA_SUSPEND);
>
> Do we need to check if the device is started or not here?
>
v->vhost_started is checked right above, right?
> > + }
>
> I'm not sure I understand the reason for vhost_net_stop() after a
> VHOST_VDPA_SUSPEND. It looks to me those functions are duplicated.
>
I think this is really worth exploring, and it would have been clearer
if I didn't squash the vhost_reset_status commit by mistake :).
Looking at qemu master vhost.c:vhost_dev_stop:
if (hdev->vhost_ops->vhost_dev_start) {
hdev->vhost_ops->vhost_dev_start(hdev, false);
}
if (vrings) {
vhost_dev_set_vring_enable(hdev, false);
}
for (i = 0; i < hdev->nvqs; ++i) {
vhost_virtqueue_stop(hdev,
vdev,
hdev->vqs + i,
hdev->vq_index + i);
}
Both vhost-used and vhost-vdpa set_status(0) at
->vhost_dev_start(hdev, false). It cleans virtqueue state in vdpa so
they are not recoverable at vhost_virtqueue_stop->get_vring_base, and
I think it is too late for vdpa devices to change it. I guess
vhost-user devices do not lose the state there, but I did not test.
I call VHOST_VDPA_SUSPEND here so vhost_vdpa_dev_start looks more
similar to vhost_user_dev_start. We can make
vhost_vdpa_dev_start(false) to suspend the device instead. But then we
need to reset it after getting the indexes. That's why I added
vhost_vdpa_reset_status, but I admit it is neither the cleanest
approach nor the best name to it.
Adding Maxime, RFC here so we can make -vdpa and -user not to divert too much.
> > + data_queue_pairs = n->multiqueue ? n->max_queue_pairs : 1;
> > + cvq = virtio_vdev_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ) ?
> > + n->max_ncs - n->max_queue_pairs : 0;
> > + vhost_net_stop(vdev, n->nic->ncs, data_queue_pairs, cvq);
> > +
> > + peer = s->nc.peer;
> > + for (int i = 0; i < data_queue_pairs + cvq; i++) {
> > + VhostVDPAState *vdpa_state;
> > + NetClientState *nc;
> > +
> > + if (i < data_queue_pairs) {
> > + nc = qemu_get_peer(peer, i);
> > + } else {
> > + nc = qemu_get_peer(peer, n->max_queue_pairs);
> > + }
> > +
> > + vdpa_state = DO_UPCAST(VhostVDPAState, nc, nc);
> > + vdpa_state->vhost_vdpa.shadow_data = enable;
> > +
> > + if (i < data_queue_pairs) {
> > + /* Do not override CVQ shadow_vqs_enabled */
> > + vdpa_state->vhost_vdpa.shadow_vqs_enabled = enable;
> > + }
> > + }
> > +
> > + r = vhost_net_start(vdev, n->nic->ncs, data_queue_pairs, cvq);
> > + if (unlikely(r < 0)) {
> > + error_report("unable to start vhost net: %s(%d)", g_strerror(-r),
> > -r);
> > + }
> > +}
> > +
> > +static void vdpa_net_migration_state_notifier(Notifier *notifier, void
> > *data)
> > +{
> > + MigrationState *migration = data;
> > + VhostVDPAState *s = container_of(notifier, VhostVDPAState,
> > + migration_state);
> > +
> > + switch (migration->state) {
> > + case MIGRATION_STATUS_SETUP:
> > + vhost_vdpa_net_log_global_enable(s, true);
> > + return;
> > +
> > + case MIGRATION_STATUS_CANCELLING:
> > + case MIGRATION_STATUS_CANCELLED:
> > + case MIGRATION_STATUS_FAILED:
> > + vhost_vdpa_net_log_global_enable(s, false);
>
> Do we need to recover here?
>
I may be missing something, but the device is fully reset and restored
in these cases.
CCing Juan and D. Gilbert, a review would be appreciated to check if
this covers all the cases.
Thanks!
> Thanks
>
> > + return;
> > + };
> > +}
> > +
> > static void vhost_vdpa_net_data_start_first(VhostVDPAState *s)
> > {
> > struct vhost_vdpa *v = &s->vhost_vdpa;
> >
> > + if (v->feature_log) {
> > + add_migration_state_change_notifier(&s->migration_state);
> > + }
> > +
> > if (v->shadow_vqs_enabled) {
> > v->iova_tree = vhost_iova_tree_new(v->iova_range.first,
> > v->iova_range.last);
> > @@ -280,6 +359,10 @@ static void vhost_vdpa_net_client_stop(NetClientState
> > *nc)
> >
> > assert(nc->info->type == NET_CLIENT_DRIVER_VHOST_VDPA);
> >
> > + if (s->vhost_vdpa.index == 0 && s->vhost_vdpa.feature_log) {
> > + remove_migration_state_change_notifier(&s->migration_state);
> > + }
> > +
> > dev = s->vhost_vdpa.dev;
> > if (dev->vq_index + dev->nvqs == dev->vq_index_end) {
> > g_clear_pointer(&s->vhost_vdpa.iova_tree, vhost_iova_tree_delete);
> > @@ -767,6 +850,7 @@ static NetClientState
> > *net_vhost_vdpa_init(NetClientState *peer,
> > s->vhost_vdpa.device_fd = vdpa_device_fd;
> > s->vhost_vdpa.index = queue_pair_index;
> > s->always_svq = svq;
> > + s->migration_state.notify = vdpa_net_migration_state_notifier;
> > s->vhost_vdpa.shadow_vqs_enabled = svq;
> > s->vhost_vdpa.iova_range = iova_range;
> > s->vhost_vdpa.shadow_data = svq;
> > --
> > 2.31.1
> >
>
>
- [RFC v2 08/13] vdpa: Negotiate _F_SUSPEND feature, (continued)
[RFC v2 09/13] vdpa: add feature_log parameter to vhost_vdpa, Eugenio Pérez, 2023/01/12
[RFC v2 10/13] vdpa net: allow VHOST_F_LOG_ALL, Eugenio Pérez, 2023/01/12
[RFC v2 11/13] vdpa: add vdpa net migration state notifier, Eugenio Pérez, 2023/01/12
[RFC v2 12/13] vdpa: preemptive kick at enable, Eugenio Pérez, 2023/01/12