"Michael S. Tsirkin" <m...@redhat.com> writes: > On Wed, Aug 14, 2024 at 04:05:34PM +1000, Nicholas Piggin wrote: >> On Wed Aug 14, 2024 at 6:48 AM AEST, Michael S. Tsirkin wrote: >> > On Tue, Aug 13, 2024 at 09:23:24PM +0100, Alex Bennée wrote: >> > > From: Nicholas Piggin <npig...@gmail.com> >> > > >> > > The regular qemu_bh_schedule() calls result in non-deterministic >> > > execution of the bh in record-replay mode, which causes replay failure. >> > > >> > > Reviewed-by: Alex Bennée <alex.ben...@linaro.org> >> > > Reviewed-by: Pavel Dovgalyuk <pavel.dovgal...@ispras.ru> >> > > Signed-off-by: Nicholas Piggin <npig...@gmail.com> >> > > Message-Id: <20240813050638.446172-9-npig...@gmail.com> >> > > Signed-off-by: Alex Bennée <alex.ben...@linaro.org> >> > > --- >> > > hw/net/virtio-net.c | 11 ++++++----- >> > > 1 file changed, 6 insertions(+), 5 deletions(-) >> > > >> > > diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c >> > > index 08aa0b65e3..10ebaae5e2 100644 >> > > --- a/hw/net/virtio-net.c >> > > +++ b/hw/net/virtio-net.c >> > > @@ -40,6 +40,7 @@ >> > > #include "migration/misc.h" >> > > #include "standard-headers/linux/ethtool.h" >> > > #include "sysemu/sysemu.h" >> > > +#include "sysemu/replay.h" >> > > #include "trace.h" >> > > #include "monitor/qdev.h" >> > > #include "monitor/monitor.h" >> > > @@ -417,7 +418,7 @@ static void virtio_net_set_status(struct >> > > VirtIODevice *vdev, uint8_t status) >> > > timer_mod(q->tx_timer, >> > > qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + >> > > n->tx_timeout); >> > > } else { >> > > - qemu_bh_schedule(q->tx_bh); >> > > + replay_bh_schedule_event(q->tx_bh); >> > > } >> > > } else { >> > > if (q->tx_timer) { >> > > @@ -2672,7 +2673,7 @@ static void virtio_net_tx_complete(NetClientState >> > > *nc, ssize_t len) >> > > */ >> > > virtio_queue_set_notification(q->tx_vq, 0); >> > > if (q->tx_bh) { >> > > - qemu_bh_schedule(q->tx_bh); >> > > + replay_bh_schedule_event(q->tx_bh); >> > > } else { >> > > timer_mod(q->tx_timer, >> > > qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + >> > > n->tx_timeout); >> > > @@ -2838,7 +2839,7 @@ static void virtio_net_handle_tx_bh(VirtIODevice >> > > *vdev, VirtQueue *vq) >> > > return; >> > > } >> > > virtio_queue_set_notification(vq, 0); >> > > - qemu_bh_schedule(q->tx_bh); >> > > + replay_bh_schedule_event(q->tx_bh); >> > > } >> > > >> > > static void virtio_net_tx_timer(void *opaque) >> > > @@ -2921,7 +2922,7 @@ static void virtio_net_tx_bh(void *opaque) >> > > /* If we flush a full burst of packets, assume there are >> > > * more coming and immediately reschedule */ >> > > if (ret >= n->tx_burst) { >> > > - qemu_bh_schedule(q->tx_bh); >> > > + replay_bh_schedule_event(q->tx_bh); >> > > q->tx_waiting = 1; >> > > return; >> > > } >> > > @@ -2935,7 +2936,7 @@ static void virtio_net_tx_bh(void *opaque) >> > > return; >> > > } else if (ret > 0) { >> > > virtio_queue_set_notification(q->tx_vq, 0); >> > > - qemu_bh_schedule(q->tx_bh); >> > > + replay_bh_schedule_event(q->tx_bh); >> > > q->tx_waiting = 1; >> > > } >> > > } >> > > -- >> > > 2.39.2 >> > >> > >> > Is this really the only way to fix this? I do not think >> > virtio has any business knowing about replay. >> > What does this API do, even? BH but not broken with replay? >> > Do we ever want replay broken? Why not fix qemu_bh_schedule? >> > And when we add another feature which we do not want to break >> > will we do foo_bar_replay_bh_schedule_event or what? >> >> I agree with you. We need to do this (a couple of other hw >> subsystems already do and likely some are still broken vs >> replay and would need to be converted), but I think it's >> mostly a case of bad naming. You're right the caller should >> not know about replay at all, what it should be is whether >> the event is for the target machine or the host harness, >> same as timers are VIRTUAL / HOST. >> So I think we just need to make a qemu_bh_schedule_<type>, >> or qemu_bh_scheudle_event(... QEMU_EVENT_VIRTUAL/HOST/etc). > > Or just pass QEMUClockType?
Is this wider re-factoring something that can wait for the next developer cycle? >> I had started on a conversion once but not completed it. >> I could resurrect if there is agreement on the API? I would certainly welcome it being cleaned up. The supported replay devices are very piecemeal at the moment. >> >> Thanks, >> Nick -- Alex Bennée Virtualisation Tech Lead @ Linaro