Re: [Qemu-devel] [Question] virtio-serial misses irq delivery on migration?

[Gonglei (Arei)]

Hello Paolo,

Any ideas? Thanks!


Regards,
-Gonglei


> -----Original Message-----
> From: Gonglei (Arei)
> Sent: Saturday, August 06, 2016 6:20 PM
> To: Gonglei (Arei); 'Paolo Bonzini'; 'address@hidden';
> 'address@hidden'; 'address@hidden'
> Cc: 'address@hidden'; 'address@hidden'; Huangweidong (C)
> Subject: RE: [Question] virtio-serial misses irq delivery on migration?
> 
> Hi all,
> 
> I might catch the bug. Now, we rely on a vm_clock timer to assure that the
> vcpus are started
> before we invoke send_control_event(),which queue a message in the virtio
> ring and trigger a irq.
> 
> In actually, we can't attach our initial intention under a special situation:
> 
> 1. the process of migration destination is in a coroutine
>  Commit 82a4da79fd6
> 2. The corountine will yiled the cpu (calling yield_until_fd_readable(s->fd))
>  if the Qemu encounter a EAGIN while reading QEMUFile.
>  commit 595ab64169b
> 
> static ssize_t socket_get_buffer(void *opaque, uint8_t *buf, int64_t pos,
>                                  size_t size)
> {
>     QEMUFileSocket *s = opaque;
>     ssize_t len;
> 
>     for (;;) {
>         len = qemu_recv(s->fd, buf, size, 0);
>         if (len != -1) {
>             break;
>         }
>         if (socket_error() == EAGAIN) {
>             yield_until_fd_readable(s->fd);
>         } else if (socket_error() != EINTR) {
>             break;
>         }
>     }
> 
>     if (len == -1) {
>         len = -socket_error();
>     }
>     return len;
> }
> 
> 3. The main thread can get the cpu and timer will run, asumes that we get
> EAGIN
>   after invoking fetch_active_ports_list().
> 4. reproduce the problem by fault injection.
> 
> The debug logs:
> 
> [2016-08-06 16:52:56] handle_qmp_command:5106 qmp_cmd_name:
> query-migrate-capabilities
> [2016-08-06 16:52:56] handle_qmp_command:5116 qmp_cmd_name:
> migrate-set-capabilities, qmp_cmd_arguments: {"capabilities": [{"state": 
> false,
> "capability": "xbzrle"}]}
> [2016-08-06 16:52:56] handle_qmp_command:5106 qmp_cmd_name:
> query-migrate-capabilities
> [2016-08-06 16:52:56] handle_qmp_command:5116 qmp_cmd_name:
> migrate-set-capabilities, qmp_cmd_arguments: {"capabilities": [{"state": 
> false,
> "capability": "rdma-pin-all"}]}
> [2016-08-06 16:52:56] process_incoming_migration_co:170 gonglei: enter
> process_incoming_migration_co()    // Enter corountine
> [2016-08-06 16:53:01] apic_dispatch_post_load:370 gonglei:
> apic_dispatch_post_load
> [2016-08-06 16:53:01] apic_dispatch_post_load:370 gonglei:
> apic_dispatch_post_load
> [2016-08-06 16:53:01] apic_dispatch_post_load:370 gonglei:
> apic_dispatch_post_load
> [2016-08-06 16:53:01] apic_dispatch_post_load:370 gonglei:
> apic_dispatch_post_load
> [2016-08-06 16:53:01] apic_dispatch_post_load:370 gonglei:
> apic_dispatch_post_load
> [2016-08-06 16:53:01] apic_dispatch_post_load:370 gonglei:
> apic_dispatch_post_load
> [2016-08-06 16:53:01] apic_dispatch_post_load:370 gonglei:
> apic_dispatch_post_load
> [2016-08-06 16:53:01] apic_dispatch_post_load:370 gonglei:
> apic_dispatch_post_load
> [2016-08-06 16:53:01] kvm_ioapic_put:97 gonglei: kvm_ioapic_put
> [2016-08-06 16:53:01] virtio_serial_load:745 gonglei: virtio_serial_load will 
> init
> virtqueue
> [2016-08-06 16:53:01] fetch_active_ports_list:735 gonglei: **************
> begin to inject debug **********    // fault injection begin, migration
> coroutine yiled cpu
> [2016-08-06 16:53:01] timerlist_run_timers:496 gonglei: expire_time: 1,
> current_time: 9750771061592    //vm_clock timer boom
> [2016-08-06 16:53:01] virtio_serial_post_load_timer_cb:658 gonglei:
> virtio_serial_post_load_timer_cb   //calling the timer callback
> [2016-08-06 16:53:01] send_control_event:225 virtio serial port 1 send control
> message event = 6, value = 0 // send a message to the guest, raise the irq 
> line.
> [2016-08-06 16:53:01] virtio_serial_post_load_timer_cb:669 gonglei:
> port->host_connected: 0
> [2016-08-06 16:53:01] monitor_qapi_event_emit:483 {"timestamp":
> {"seconds": 1470473581, "microseconds": 64056}, "event":
> "VSERPORT_CHANGE", "data": {"open": true, "id": "channel0"}}
> [2016-08-06 16:53:01] send_control_event:225 virtio serial port 3 send control
> message event = 6, value = 0
> [2016-08-06 16:53:01] virtio_serial_post_load_timer_cb:669 gonglei:
> port->host_connected: 0
> [2016-08-06 16:53:01] timerlist_run_timers:496 gonglei: expire_time:
> 9750770788478, current_time: 9750771061592
> [2016-08-06 16:53:01] kvm_put_apic_state:32 gonglei: kvm_put_apic_state
> //Enter migration coroutine again, and the restore the lapic register, the
> previous lapic's info will be covered :(
> [2016-08-06 16:53:01] kvm_put_apic_state:32 gonglei: kvm_put_apic_state
> [2016-08-06 16:53:01] kvm_put_apic_state:32 gonglei: kvm_put_apic_state
> [2016-08-06 16:53:01] kvm_put_apic_state:32 gonglei: kvm_put_apic_state
> [2016-08-06 16:53:01] kvm_put_apic_state:32 gonglei: kvm_put_apic_state
> [2016-08-06 16:53:01] kvm_put_apic_state:32 gonglei: kvm_put_apic_state
> [2016-08-06 16:53:01] kvm_put_apic_state:32 gonglei: kvm_put_apic_state
> [2016-08-06 16:53:01] kvm_put_apic_state:32 gonglei: kvm_put_apic_state
> [2016-08-06 16:53:01] handle_qmp_command:5106 qmp_cmd_name: cont
> [2016-08-06 16:53:01] qmp_cont:189 qmp cont is received and vm is started
> [2016-08-06 16:53:01] vm_start:981 gonglei: enter vm_start
> //enter vm_start here
> [2016-08-06 16:53:01] virtio_set_status:522 virtio-net device status is 7 that
> means DRIVER OK
> [2016-08-06 16:53:01] virtio_set_status:522 virtio-serial device status is 7 
> that
> means DRIVER OK
> [2016-08-06 16:53:01] virtio_set_status:522 virtio-scsi device status is 7 
> that
> means DRIVER OK
> [2016-08-06 16:53:01] vm_start:1000 vm_state-notify:23ms
> [2016-08-06 16:53:01] qemu_clock_enable:163 gonglei: type: 1, enabled: 1, old:
> 1
> [2016-08-06 16:53:01] monitor_qapi_event_emit:483 {"timestamp":
> {"seconds": 1470473581, "microseconds": 112191}, "event": "RESUME"}
> [2016-08-06 16:53:01] timerlist_run_timers:496 gonglei: expire_time:
> 9750772061592, current_time: 9750794269805
> [2016-08-06 16:53:01] send_control_event:225 virtio serial port 1 send control
> message event = 6, value = 1
> [2016-08-06 16:53:01] timerlist_run_timers:496 gonglei: expire_time:
> 9750795284148, current_time: 9750795312685
> [2016-08-06 16:53:01] send_control_event:225 virtio serial port 3 send control
> message event = 6, value = 1
> [2016-08-06 16:53:01] timerlist_run_timers:496 gonglei: expire_time:
> 9750796329656, current_time: 9750796369458
> [2016-08-06 16:53:01] timerlist_run_timers:496 gonglei: expire_time:
> 9750797396208, current_time: 9750797426752
> [2016-08-06 16:53:01] timerlist_run_timers:496 gonglei: expire_time:
> 9750798445707, current_time: 9750798477520
> [2016-08-06 16:53:01] timerlist_run_timers:496 gonglei: expire_time:
> 9750799496162, current_time: 9750799532183
> [2016-08-06 16:53:01] timerlist_run_timers:496 gonglei: expire_time:
> 9750800556817, current_time: 9750800588741
> [2016-08-06 16:53:01] timerlist_run_timers:496 gonglei: expire_time:
> 9750801606596, current_time: 9750801637961
> 
> 
> The below is my debugging diff (Not based on the newest master branch)
> 
> diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c
> index 6a45af9..a00b02f 100644
> --- a/hw/char/virtio-serial-bus.c
> +++ b/hw/char/virtio-serial-bus.c
> @@ -654,6 +654,7 @@ static void virtio_serial_post_load_timer_cb(void
> *opaque)
>      if (!s->post_load) {
>          return;
>      }
> +    QEMU_LOG("gonglei: virtio_serial_post_load_timer_cb\n");
>      for (i = 0 ; i < s->post_load->nr_active_ports; ++i) {
>          port = s->post_load->connected[i].port;
>          host_connected = s->post_load->connected[i].host_connected;
> @@ -664,6 +665,7 @@ static void virtio_serial_post_load_timer_cb(void
> *opaque)
>               */
>              send_control_event(s, port->id,
> VIRTIO_CONSOLE_PORT_OPEN,
>                                 port->host_connected);
> +            QEMU_LOG("gonglei: port->host_connected: %u\n",
> port->host_connected);
>          }
>          vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
>          if (vsc->set_guest_connected) {
> @@ -729,6 +731,8 @@ static int fetch_active_ports_list(QEMUFile *f, int
> version_id,
>          }
>      }
>      timer_mod(s->post_load->timer, 1);
> +    QEMU_LOG("gonglei: ************** begin to inject debug
> **********\n");
> +    yield_until_fd_readable(qemu_get_fd(f));
>      return 0;
>  }
> 
> @@ -737,7 +741,7 @@ static int virtio_serial_load(QEMUFile *f, void *opaque,
> int version_id)
>      if (version_id > 3) {
>          return -EINVAL;
>      }
> -
> +    QEMU_LOG("gonglei: virtio_serial_load will init virtqueue\n");
>      /* The virtio device */
>      return virtio_load(VIRTIO_DEVICE(opaque), f, version_id);
>  }
> diff --git a/hw/i386/kvm/apic.c b/hw/i386/kvm/apic.c
> index 5b47056..2d988cb 100644
> --- a/hw/i386/kvm/apic.c
> +++ b/hw/i386/kvm/apic.c
> @@ -29,7 +29,7 @@ void kvm_put_apic_state(DeviceState *dev, struct
> kvm_lapic_state *kapic)
>  {
>      APICCommonState *s = APIC_COMMON(dev);
>      int i;
> -
> +    QEMU_LOG("gonglei: kvm_put_apic_state\n");
>      memset(kapic, 0, sizeof(*kapic));
>      kvm_apic_set_reg(kapic, 0x2, s->id << 24);
>      kvm_apic_set_reg(kapic, 0x8, s->tpr);
> diff --git a/hw/i386/kvm/ioapic.c b/hw/i386/kvm/ioapic.c
> index d2a6c4c..07699ec 100644
> --- a/hw/i386/kvm/ioapic.c
> +++ b/hw/i386/kvm/ioapic.c
> @@ -94,7 +94,7 @@ static void kvm_ioapic_put(IOAPICCommonState *s)
> 
>      chip.chip_id = KVM_IRQCHIP_IOAPIC;
>      kioapic = &chip.chip.ioapic;
> -
> +    QEMU_LOG("gonglei: kvm_ioapic_put\n");
>      kioapic->id = s->id;
>      kioapic->ioregsel = s->ioregsel;
>      kioapic->base_address = s->busdev.mmio[0].addr;
> diff --git a/hw/intc/apic_common.c b/hw/intc/apic_common.c
> index 042e960..110be20 100644
> --- a/hw/intc/apic_common.c
> +++ b/hw/intc/apic_common.c
> @@ -366,6 +366,7 @@ static int apic_dispatch_post_load(void *opaque, int
> version_id)
>      if (info->post_load) {
>          info->post_load(s);
>      }
> +    QEMU_LOG("gonglei: apic_dispatch_post_load\n");
>      return 0;
>  }
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index 92c1427..d074c0a 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -167,7 +167,7 @@ static void process_incoming_migration_co(void
> *opaque)
>      const char *arpGuestCMD = "{\"execute\":\"guest-write-flag-arp\"}\n";
>      const char *portName = "charchannel1";
>      size_t uRet;
> -
> +    QEMU_LOG("gonglei: enter process_incoming_migration_co()\n");
>      ret = qemu_loadvm_state(f);
>      qemu_fclose(f);
>      free_xbzrle_decoded_buf();
> diff --git a/qemu-timer.c b/qemu-timer.c
> index 5741f0d..dd36bc9 100644
> --- a/qemu-timer.c
> +++ b/qemu-timer.c
> @@ -160,6 +160,7 @@ void qemu_clock_enable(QEMUClockType type, bool
> enabled)
>      QEMUTimerList *tl;
>      bool old = clock->enabled;
>      clock->enabled = enabled;
> +    QEMU_LOG("gonglei: type: %u, enabled: %u, old: %u\n", type, enabled,
> old);
>      if (enabled && !old) {
>          qemu_clock_notify(type);
>      } else if (!enabled && old) {
> @@ -475,6 +476,7 @@ bool timerlist_run_timers(QEMUTimerList *timer_list)
>      bool progress = false;
>      QEMUTimerCB *cb;
>      void *opaque;
> +    static int count = 10;
> 
>      qemu_event_reset(&timer_list->timers_done_ev);
>      if (!timer_list->clock->enabled) {
> @@ -489,7 +491,10 @@ bool timerlist_run_timers(QEMUTimerList
> *timer_list)
>              qemu_mutex_unlock(&timer_list->active_timers_lock);
>              break;
>          }
> -
> +     if (timer_list->clock->type == QEMU_CLOCK_VIRTUAL && count-- > 0) {
> +         QEMU_LOG("gonglei: expire_time: %lld, current_time: %lld\n",
> +             ts->expire_time, current_time);
> +     }
>          /* remove timer from the list before calling the callback */
>          timer_list->active_timers = ts->next;
>          ts->next = NULL;
> diff --git a/vl.c b/vl.c
> index 06f34fe..824b246 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -978,7 +978,7 @@ void vm_start(void)
>  {
>      RunState requested;
>      int64_t start_time, end_time;
> -
> +    QEMU_LOG("gonglei: enter vm_start\n");
>      qemu_vmstop_requested(&requested);
>      if (runstate_is_running() && requested == RUN_STATE_MAX) {
>          return;
> 
> 
> Can we wait looply the migration process finished when EAGAIN?
> 
> Regards,
> -Gonglei
> 
> 
> > -----Original Message-----
> > From: Gonglei (Arei)
> > Sent: Friday, August 05, 2016 5:14 PM
> > To: Paolo Bonzini; 'address@hidden'; 'address@hidden'
> > Cc: address@hidden; address@hidden; Huangweidong (C)
> > Subject: [Question] virtio-serial misses irq delivery on migration?
> >
> > Hi Paolo , Jan, Amit
> >
> > Recently we encountered a problem that the virtio-serial can't work after
> > Migration in RH5.5 VM. The bigger problem is, I can't reproduce it. :(
> >
> > It's phenomenon was much like BZ 867366, the usb-table mouse didn't work
> > because
> > the uhci and virtio-serial shard the irq line (using IOAPIC, not MSI). The 
> > new
> > interrupt
> > can't be injected to VM because the irq line bit had been set to 1, but the
> > frontend
> > driver never handle it or never know it.
> >
> >  Bug 867366 - virtio-serial misses irq delivery on migration
> > https://bugzilla.redhat.com/show_bug.cgi?id=867366
> >
> > But my qemu is the newest qemu, Both commit 80dcfb8532"virtio-serial-bus:
> > post_load
> > send_event when vm is running" and commit bc6b815d9e " virtio-serial:
> > propagate
> > guest_connected to the port on post_load" are applied.
> >
> > I noticed that Paolo posted another problem maybe have a pertential
> problem
> > about
> > apic in Comment 23. But this patch
> >  https://bugzilla.redhat.com/attachment.cgi?id=635535&action=diff
> > haven't merged into qemu master.
> >
> > Would you give me some clues please? Thanks!
> >
> > Regards,
> > -Gonglei
> >