On Mon, Jan 16, 2023 at 7:51 AM Jason Wang <jasow...@redhat.com> wrote:
>
>
> 在 2023/1/13 17:00, Eugenio Perez Martin 写道:
> > On Fri, Jan 13, 2023 at 5:55 AM Jason Wang <jasow...@redhat.com> wrote:
> >> On Fri, Jan 13, 2023 at 1:25 AM Eugenio Pérez <epere...@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 <epere...@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?
>
>
> Right, I miss that.
>
>
> >
> >>> + }
> >> 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.
>
>
> I wonder if we can simply suspend in vhost_net_stop() if we know the
> parent can stop?
>
Sure, that's possible, I'll move that code to vhost_net_stop.
Thanks!
> Thanks
>
>
> >
> > 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
> >>>
> >>
>
