[v12,2/2] migration: spapr: migrate pending_events of spapr state

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 a binary stream inside VBUFFER 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>
---
 hw/ppc/spapr.c         | 32 ++++++++++++++++++++++++++++++++
 hw/ppc/spapr_events.c  | 12 ++++++++++++
 include/hw/ppc/spapr.h |  3 ++-
 3 files changed, 46 insertions(+), 1 deletion(-)

Quoting Daniel Henrique Barboza (2017-05-19 09:27:50)
> 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 a binary stream inside VBUFFER 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>

Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>

> ---
>  hw/ppc/spapr.c         | 32 ++++++++++++++++++++++++++++++++
>  hw/ppc/spapr_events.c  | 12 ++++++++++++
>  include/hw/ppc/spapr.h |  3 ++-
>  3 files changed, 46 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 0980d73..5afd328 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1444,6 +1444,37 @@ 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_UINT32(data_size, sPAPREventLogEntry),
> +        VMSTATE_VBUFFER_ALLOC_UINT32(data, sPAPREventLogEntry, 0,
> +                                     NULL, data_size),
> +        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;
> @@ -1542,6 +1573,7 @@ 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 73e2a18..a509c46 100644
> --- a/hw/ppc/spapr_events.c
> +++ b/hw/ppc/spapr_events.c
> @@ -350,6 +350,18 @@ static void rtas_event_log_queue(int log_type, void *data)
>      g_assert(data);
>      entry->log_type = log_type;
>      entry->data = data;
> +
> +    switch (log_type) {
> +    case RTAS_LOG_TYPE_EPOW:
> +        entry->data_size = sizeof(struct epow_log_full);
> +        break;
> +    case RTAS_LOG_TYPE_HOTPLUG:
> +        entry->data_size = sizeof(struct hp_log_full);
> +        break;
> +    default:
> +        g_assert(false);
> +    }
> +
>      QTAILQ_INSERT_TAIL(&spapr->pending_events, entry, next);
>  }
> 
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 02239a5..0554e11 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -597,8 +597,9 @@ struct sPAPRTCETable {
>  sPAPRTCETable *spapr_tce_find_by_liobn(target_ulong liobn);
> 
>  struct sPAPREventLogEntry {
> -    int log_type;
> +    int32_t log_type;
>      void *data;
> +    uint32_t data_size;
>      QTAILQ_ENTRY(sPAPREventLogEntry) next;
>  };
> 
> -- 
> 2.9.4
>

On Fri, May 19, 2017 at 11:27:50AM -0300, Daniel Henrique Barboza wrote:
> 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 a binary stream inside VBUFFER 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>
> ---
>  hw/ppc/spapr.c         | 32 ++++++++++++++++++++++++++++++++
>  hw/ppc/spapr_events.c  | 12 ++++++++++++
>  include/hw/ppc/spapr.h |  3 ++-
>  3 files changed, 46 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 0980d73..5afd328 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1444,6 +1444,37 @@ 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_UINT32(data_size, sPAPREventLogEntry),
> +        VMSTATE_VBUFFER_ALLOC_UINT32(data, sPAPREventLogEntry, 0,
> +                                     NULL, data_size),
> +        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;
> @@ -1542,6 +1573,7 @@ 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 73e2a18..a509c46 100644
> --- a/hw/ppc/spapr_events.c
> +++ b/hw/ppc/spapr_events.c
> @@ -350,6 +350,18 @@ static void rtas_event_log_queue(int log_type, void *data)
>      g_assert(data);
>      entry->log_type = log_type;
>      entry->data = data;
> +
> +    switch (log_type) {
> +    case RTAS_LOG_TYPE_EPOW:
> +        entry->data_size = sizeof(struct epow_log_full);
> +        break;
> +    case RTAS_LOG_TYPE_HOTPLUG:
> +        entry->data_size = sizeof(struct hp_log_full);
> +        break;
> +    default:
> +        g_assert(false);
> +    }

You can do better than this.  The header of the event has an
'extended_length' field which is set (correctly) by the existing
functions creating the events.  You'll need to add the base/common
header size back in, but that's easy.

That's how the guest determines the size of the events once they
arrive, and that's what you should use here as well.

> +
>      QTAILQ_INSERT_TAIL(&spapr->pending_events, entry, next);
>  }
>  
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 02239a5..0554e11 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -597,8 +597,9 @@ struct sPAPRTCETable {
>  sPAPRTCETable *spapr_tce_find_by_liobn(target_ulong liobn);
>  
>  struct sPAPREventLogEntry {
> -    int log_type;
> +    int32_t log_type;
>      void *data;
> +    uint32_t data_size;
>      QTAILQ_ENTRY(sPAPREventLogEntry) next;
>  };
>