Re: [Qemu-devel] [PATCH v10] migration: spapr: migrate pending_events of spapr state

[David Gibson <david@gibson.dropbear.id.au>]

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On Mon, May 15, 2017 at 10:26:46PM -0500, Michael Roth wrote:
> Quoting Daniel Henrique Barboza (2017-05-15 08:10:52)
> > From: Jianjun Duan <duanj@linux.vnet.ibm.com>
> > 
> > In racing situations between hotplug events and migration operation,
> > a rtas hotplug event could have not yet be delivered to the source
> > guest when migration is started. In this case the pending_events of
> > spapr state need be transmitted to the target so that the hotplug
> > event can be finished on the target.
> > 
> > All the different fields of the events are encoded as defined by
> > PAPR. We can migrate them as uint8_t binary stream without any
> > concerns about data padding or endianess.
> > 
> > pending_events is put in a subsection in the spapr state VMSD to make
> > sure migration across different versions is not broken.
> > 
> > Signed-off-by: Jianjun Duan <duanj@linux.vnet.ibm.com>
> > Signed-off-by: Daniel Henrique Barboza <danielhb@linux.vnet.ibm.com>
> 
> I'd also be a little weary of treating this patch as totally standalone.
> There's pros/cons, but, without migrated DRC state, migrated hotplug
> events won't necessarilly be handled better than the current behavior of
> just dropping them.

True, but alone it should at least stop powerdown messages being lost
on migration, which is also possible AFAICT.

> 
> > ---
> >  hw/ppc/spapr.c         | 33 +++++++++++++++++++++++++++++++++
> >  hw/ppc/spapr_events.c  | 24 +++++++++++++-----------
> >  include/hw/ppc/spapr.h |  3 ++-
> >  3 files changed, 48 insertions(+), 12 deletions(-)
> > 
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index 80d12d0..8cfdc71 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -1437,6 +1437,38 @@ static bool version_before_3(void *opaque, int version_id)
> >      return version_id < 3;
> >  }
> > 
> > +static bool spapr_pending_events_needed(void *opaque)
> > +{
> > +    sPAPRMachineState *spapr = (sPAPRMachineState *)opaque;
> > +    return !QTAILQ_EMPTY(&spapr->pending_events);
> > +}
> > +
> > +static const VMStateDescription vmstate_spapr_event_entry = {
> > +    .name = "spapr_event_log_entry",
> > +    .version_id = 1,
> > +    .minimum_version_id = 1,
> > +    .fields = (VMStateField[]) {
> > +        VMSTATE_INT32(log_type, sPAPREventLogEntry),
> > +        VMSTATE_BOOL(exception, sPAPREventLogEntry),
> > +        VMSTATE_UINT32(data_size, sPAPREventLogEntry),
> > +        VMSTATE_VARRAY_UINT32_ALLOC(data, sPAPREventLogEntry, data_size,
> > +                                    0, vmstate_info_uint8, uint8_t),
> > +        VMSTATE_END_OF_LIST()
> > +    },
> > +};
> > +
> > +static const VMStateDescription vmstate_spapr_pending_events = {
> > +    .name = "spapr_pending_events",
> > +    .version_id = 1,
> > +    .minimum_version_id = 1,
> > +    .needed = spapr_pending_events_needed,
> > +    .fields = (VMStateField[]) {
> > +        VMSTATE_QTAILQ_V(pending_events, sPAPRMachineState, 1,
> > +                         vmstate_spapr_event_entry, sPAPREventLogEntry, next),
> > +        VMSTATE_END_OF_LIST()
> > +    },
> > +};
> > +
> >  static bool spapr_ov5_cas_needed(void *opaque)
> >  {
> >      sPAPRMachineState *spapr = opaque;
> > @@ -1535,6 +1567,7 @@ static const VMStateDescription vmstate_spapr = {
> >      .subsections = (const VMStateDescription*[]) {
> >          &vmstate_spapr_ov5_cas,
> >          &vmstate_spapr_patb_entry,
> > +        &vmstate_spapr_pending_events,
> >          NULL
> >      }
> >  };
> > diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c
> > index f0b28d8..70c7cfc 100644
> > --- a/hw/ppc/spapr_events.c
> > +++ b/hw/ppc/spapr_events.c
> > @@ -342,7 +342,8 @@ static int rtas_event_log_to_irq(sPAPRMachineState *spapr, int log_type)
> >      return source->irq;
> >  }
> > 
> > -static void rtas_event_log_queue(int log_type, void *data, bool exception)
> > +static void rtas_event_log_queue(int log_type, void *data, bool exception,
> > +                                 int data_size)
> >  {
> >      sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
> >      sPAPREventLogEntry *entry = g_new(sPAPREventLogEntry, 1);
> > @@ -351,6 +352,7 @@ static void rtas_event_log_queue(int log_type, void *data, bool exception)
> >      entry->log_type = log_type;
> >      entry->exception = exception;
> >      entry->data = data;
> > +    entry->data_size = data_size;
> >      QTAILQ_INSERT_TAIL(&spapr->pending_events, entry, next);
> >  }
> > 
> > @@ -445,6 +447,7 @@ static void spapr_powerdown_req(Notifier *n, void *opaque)
> >      struct rtas_event_log_v6_mainb *mainb;
> >      struct rtas_event_log_v6_epow *epow;
> >      struct epow_log_full *new_epow;
> > +    uint32_t data_size;
> > 
> >      new_epow = g_malloc0(sizeof(*new_epow));
> >      hdr = &new_epow->hdr;
> > @@ -453,14 +456,13 @@ static void spapr_powerdown_req(Notifier *n, void *opaque)
> >      mainb = &new_epow->mainb;
> >      epow = &new_epow->epow;
> > 
> > +    data_size = sizeof(*new_epow);
> >      hdr->summary = cpu_to_be32(RTAS_LOG_VERSION_6
> >                                 | RTAS_LOG_SEVERITY_EVENT
> >                                 | RTAS_LOG_DISPOSITION_NOT_RECOVERED
> >                                 | RTAS_LOG_OPTIONAL_PART_PRESENT
> >                                 | RTAS_LOG_TYPE_EPOW);
> > -    hdr->extended_length = cpu_to_be32(sizeof(*new_epow)
> > -                                       - sizeof(new_epow->hdr));
> > -
> > +    hdr->extended_length = cpu_to_be32(data_size - sizeof(new_epow->hdr));
> >      spapr_init_v6hdr(v6hdr);
> >      spapr_init_maina(maina, 3 /* Main-A, Main-B and EPOW */);
> > 
> > @@ -479,7 +481,7 @@ static void spapr_powerdown_req(Notifier *n, void *opaque)
> >      epow->event_modifier = RTAS_LOG_V6_EPOW_MODIFIER_NORMAL;
> >      epow->extended_modifier = RTAS_LOG_V6_EPOW_XMODIFIER_PARTITION_SPECIFIC;
> > 
> > -    rtas_event_log_queue(RTAS_LOG_TYPE_EPOW, new_epow, true);
> > +    rtas_event_log_queue(RTAS_LOG_TYPE_EPOW, new_epow, true, data_size);
> > 
> >      qemu_irq_pulse(xics_get_qirq(XICS_FABRIC(spapr),
> >                                   rtas_event_log_to_irq(spapr,
> > @@ -504,6 +506,7 @@ static void spapr_hotplug_req_event(uint8_t hp_id, uint8_t hp_action,
> >      struct rtas_event_log_v6_maina *maina;
> >      struct rtas_event_log_v6_mainb *mainb;
> >      struct rtas_event_log_v6_hp *hp;
> > +    uint32_t data_size;
> > 
> >      new_hp = g_malloc0(sizeof(struct hp_log_full));
> >      hdr = &new_hp->hdr;
> > @@ -512,14 +515,14 @@ static void spapr_hotplug_req_event(uint8_t hp_id, uint8_t hp_action,
> >      mainb = &new_hp->mainb;
> >      hp = &new_hp->hp;
> > 
> > +    data_size = sizeof(*new_hp);
> >      hdr->summary = cpu_to_be32(RTAS_LOG_VERSION_6
> >                                 | RTAS_LOG_SEVERITY_EVENT
> >                                 | RTAS_LOG_DISPOSITION_NOT_RECOVERED
> >                                 | RTAS_LOG_OPTIONAL_PART_PRESENT
> >                                 | RTAS_LOG_INITIATOR_HOTPLUG
> >                                 | RTAS_LOG_TYPE_HOTPLUG);
> > -    hdr->extended_length = cpu_to_be32(sizeof(*new_hp)
> > -                                       - sizeof(new_hp->hdr));
> > +    hdr->extended_length = cpu_to_be32(data_size - sizeof(new_hp->hdr));
> > 
> >      spapr_init_v6hdr(v6hdr);
> >      spapr_init_maina(maina, 3 /* Main-A, Main-B, HP */);
> > @@ -572,7 +575,7 @@ static void spapr_hotplug_req_event(uint8_t hp_id, uint8_t hp_action,
> >              cpu_to_be32(drc_id->count_indexed.index);
> >      }
> > 
> > -    rtas_event_log_queue(RTAS_LOG_TYPE_HOTPLUG, new_hp, true);
> > +    rtas_event_log_queue(RTAS_LOG_TYPE_HOTPLUG, new_hp, true, data_size);
> > 
> >      qemu_irq_pulse(xics_get_qirq(XICS_FABRIC(spapr),
> >                                   rtas_event_log_to_irq(spapr,
> > @@ -671,8 +674,7 @@ static void check_exception(PowerPCCPU *cpu, sPAPRMachineState *spapr,
> >      if (!event) {
> >          goto out_no_events;
> >      }
> > -
> > -    hdr = event->data;
> > +    hdr = (struct rtas_error_log *)event->data;
> >      event_len = be32_to_cpu(hdr->extended_length) + sizeof(*hdr);
> > 
> >      if (event_len < len) {
> > @@ -728,7 +730,7 @@ static void event_scan(PowerPCCPU *cpu, sPAPRMachineState *spapr,
> >          goto out_no_events;
> >      }
> > 
> > -    hdr = event->data;
> > +    hdr = (struct rtas_error_log *)event->data;
> >      event_len = be32_to_cpu(hdr->extended_length) + sizeof(*hdr);
> > 
> >      if (event_len < len) {
> > diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> > index 5802f88..fbe1d93 100644
> > --- a/include/hw/ppc/spapr.h
> > +++ b/include/hw/ppc/spapr.h
> > @@ -599,7 +599,8 @@ sPAPRTCETable *spapr_tce_find_by_liobn(target_ulong liobn);
> >  struct sPAPREventLogEntry {
> >      int log_type;
> >      bool exception;
> > -    void *data;
> > +    uint8_t *data;
> > +    uint32_t data_size;
> >      QTAILQ_ENTRY(sPAPREventLogEntry) next;
> >  };
> > 
> 

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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