Re: [Qemu-devel] [RFC v2 14/32] vhost+postcopy: Transmit 'listen' to client

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Marc-André Lureau (marcandre.lureau@gmail.com) wrote:
> On Thu, Aug 24, 2017 at 12:27 PM, Dr. David Alan Gilbert (git)
> <dgilbert@redhat.com> wrote:
> > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> >
> > Notify the vhost-user client on reception of the 'postcopy-listen'
> > event from the source.
> >
> > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > ---
> >  contrib/libvhost-user/libvhost-user.c | 21 +++++++++++++++++++++
> >  contrib/libvhost-user/libvhost-user.h |  2 ++
> >  docs/interop/vhost-user.txt           |  6 ++++++
> >  hw/virtio/trace-events                |  3 +++
> >  hw/virtio/vhost-user.c                | 30 ++++++++++++++++++++++++++++++
> >  migration/postcopy-ram.h              |  1 +
> >  migration/savevm.c                    |  7 +++++++
> >  7 files changed, 70 insertions(+)
> >
> > diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c
> > index f9b5b12b28..e8accf11db 100644
> > --- a/contrib/libvhost-user/libvhost-user.c
> > +++ b/contrib/libvhost-user/libvhost-user.c
> > @@ -15,7 +15,9 @@
> >
> >  #include <qemu/osdep.h>
> >  #include <sys/eventfd.h>
> > +#include <sys/ioctl.h>
> >  #include <sys/syscall.h>
> > +#include <linux/userfaultfd.h>
> >  #include <linux/vhost.h>
> >
> 
> Belong to an earlier patch

oops, thanks.

> >  #include "qemu/atomic.h"
> > @@ -64,6 +66,7 @@ vu_request_to_string(int req)
> >          REQ(VHOST_USER_IOTLB_MSG),
> >          REQ(VHOST_USER_SET_VRING_ENDIAN),
> >          REQ(VHOST_USER_POSTCOPY_ADVISE),
> > +        REQ(VHOST_USER_POSTCOPY_LISTEN),
> >          REQ(VHOST_USER_MAX),
> >      };
> >  #undef REQ
> > @@ -802,6 +805,22 @@ out:
> >  }
> >
> >  static bool
> > +vu_set_postcopy_listen(VuDev *dev, VhostUserMsg *vmsg)
> > +{
> > +    vmsg->payload.u64 = -1;
> > +    vmsg->size = sizeof(vmsg->payload.u64);
> > +
> > +    if (dev->nregions) {
> > +        vu_panic(dev, "Regions already registered at postcopy-listen");
> > +        return true;
> > +    }
> > +    dev->postcopy_listening = true;
> > +
> > +    vmsg->flags = VHOST_USER_VERSION |  VHOST_USER_REPLY_MASK;
> > +    vmsg->payload.u64 = 0; /* Success */
> > +    return true;
> > +}
> > +static bool
> >  vu_process_message(VuDev *dev, VhostUserMsg *vmsg)
> >  {
> >      int do_reply = 0;
> > @@ -868,6 +887,8 @@ vu_process_message(VuDev *dev, VhostUserMsg *vmsg)
> >          break;
> >      case VHOST_USER_POSTCOPY_ADVISE:
> >          return vu_set_postcopy_advise(dev, vmsg);
> > +    case VHOST_USER_POSTCOPY_LISTEN:
> > +        return vu_set_postcopy_listen(dev, vmsg);
> >      default:
> >          vmsg_close_fds(vmsg);
> >          vu_panic(dev, "Unhandled request: %d", vmsg->request);
> > diff --git a/contrib/libvhost-user/libvhost-user.h b/contrib/libvhost-user/libvhost-user.h
> > index 3e8efdd919..29c11ba56c 100644
> > --- a/contrib/libvhost-user/libvhost-user.h
> > +++ b/contrib/libvhost-user/libvhost-user.h
> > @@ -67,6 +67,7 @@ typedef enum VhostUserRequest {
> >      VHOST_USER_IOTLB_MSG        = 22,
> >      VHOST_USER_SET_VRING_ENDIAN = 23,
> >      VHOST_USER_POSTCOPY_ADVISE  = 24,
> > +    VHOST_USER_POSTCOPY_LISTEN  = 25,
> >      VHOST_USER_MAX
> >  } VhostUserRequest;
> >
> > @@ -237,6 +238,7 @@ struct VuDev {
> >
> >      /* Postcopy data */
> >      int postcopy_ufd;
> > +    bool postcopy_listening;
> >  };
> >
> >  typedef struct VuVirtqElement {
> > diff --git a/docs/interop/vhost-user.txt b/docs/interop/vhost-user.txt
> > index dad2a1b343..73c3dd74db 100644
> > --- a/docs/interop/vhost-user.txt
> > +++ b/docs/interop/vhost-user.txt
> > @@ -615,6 +615,12 @@ Master message types
> >        the slave must open a userfaultfd for later use.
> >        Note that at this stage the migration is still in precopy mode.
> >
> > + * VHOST_USER_POSTCOPY_LISTEN
> > +      Id: 25
> > +      Master payload: N/A
> > +
> > +      Master advises slave that a transition to postcopy mode has happened.
> > +
> >  Slave message types
> >  -------------------
> >
> > diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
> > index 775461ae98..f736c7c84f 100644
> > --- a/hw/virtio/trace-events
> > +++ b/hw/virtio/trace-events
> > @@ -1,5 +1,8 @@
> >  # See docs/devel/tracing.txt for syntax documentation.
> >
> > +# hw/virtio/vhost-user.c
> > +vhost_user_postcopy_listen(void) ""
> > +
> >  # hw/virtio/virtio.c
> >  virtqueue_alloc_element(void *elem, size_t sz, unsigned in_num, unsigned out_num) "elem %p size %zd in_num %u out_num %u"
> >  virtqueue_fill(void *vq, const void *elem, unsigned int len, unsigned int idx) "vq %p elem %p len %u idx %u"
> > diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> > index b7898f8939..9178271ab2 100644
> > --- a/hw/virtio/vhost-user.c
> > +++ b/hw/virtio/vhost-user.c
> > @@ -69,6 +69,7 @@ typedef enum VhostUserRequest {
> >      VHOST_USER_IOTLB_MSG = 22,
> >      VHOST_USER_SET_VRING_ENDIAN = 23,
> >      VHOST_USER_POSTCOPY_ADVISE  = 24,
> > +    VHOST_USER_POSTCOPY_LISTEN  = 25,
> >      VHOST_USER_MAX
> >  } VhostUserRequest;
> >
> > @@ -788,6 +789,32 @@ static int vhost_user_postcopy_advise(struct vhost_dev *dev, Error **errp)
> >      return 0;
> >  }
> >
> > +/*
> > + * Called at the switch to postcopy on reception of the 'listen' command.
> > + */
> > +static int vhost_user_postcopy_listen(struct vhost_dev *dev, Error **errp)
> > +{
> > +    int ret;
> > +    VhostUserMsg msg = {
> > +        .request = VHOST_USER_POSTCOPY_LISTEN,
> > +        .flags = VHOST_USER_VERSION | VHOST_USER_NEED_REPLY_MASK,
> > +    };
> > +
> > +    trace_vhost_user_postcopy_listen();
> > +    if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
> > +        error_setg(errp, "Failed to send postcopy_listen to vhost");
> > +        return -1;
> > +    }
> > +
> > +    ret = process_message_reply(dev, &msg);
> > +    if (ret) {
> > +        error_setg(errp, "Failed to receive reply to postcopy_listen");
> > +        return ret;
> > +    }
> > +
> > +    return 0;
> > +}
> > +
> >  static int vhost_user_postcopy_notifier(NotifierWithReturn *notifier,
> >                                          void *opaque)
> >  {
> > @@ -810,6 +837,9 @@ static int vhost_user_postcopy_notifier(NotifierWithReturn *notifier,
> >      case POSTCOPY_NOTIFY_INBOUND_ADVISE:
> >          return vhost_user_postcopy_advise(dev, pnd->errp);
> >
> > +    case POSTCOPY_NOTIFY_INBOUND_LISTEN:
> > +        return vhost_user_postcopy_listen(dev, pnd->errp);
> > +
> >      default:
> >          /* We ignore notifications we don't know */
> >          break;
> > diff --git a/migration/postcopy-ram.h b/migration/postcopy-ram.h
> > index 28c216cc7a..873c147b68 100644
> > --- a/migration/postcopy-ram.h
> > +++ b/migration/postcopy-ram.h
> > @@ -129,6 +129,7 @@ void postcopy_infrastructure_init(void);
> >  enum PostcopyNotifyReason {
> >      POSTCOPY_NOTIFY_PROBE = 0,
> >      POSTCOPY_NOTIFY_INBOUND_ADVISE,
> > +    POSTCOPY_NOTIFY_INBOUND_LISTEN,
> >  };
> >
> >  struct PostcopyNotifyData {
> > diff --git a/migration/savevm.c b/migration/savevm.c
> > index d35911731d..72f084e10d 100644
> > --- a/migration/savevm.c
> > +++ b/migration/savevm.c
> > @@ -1557,6 +1557,8 @@ static int loadvm_postcopy_handle_listen(MigrationIncomingState *mis)
> >  {
> >      PostcopyState ps = postcopy_state_set(POSTCOPY_INCOMING_LISTENING);
> >      trace_loadvm_postcopy_handle_listen();
> > +    Error *local_err = NULL;
> > +
> >      if (ps != POSTCOPY_INCOMING_ADVISE && ps != POSTCOPY_INCOMING_DISCARD) {
> >          error_report("CMD_POSTCOPY_LISTEN in wrong postcopy state (%d)", ps);
> >          return -1;
> > @@ -1578,6 +1580,11 @@ static int loadvm_postcopy_handle_listen(MigrationIncomingState *mis)
> >          return -1;
> >      }
> >
> > +    if (postcopy_notify(POSTCOPY_NOTIFY_INBOUND_LISTEN, &local_err)) {
> > +        error_report_err(local_err);
> > +        return -1;
> > +    }
> > +
> >      if (mis->have_listen_thread) {
> >          error_report("CMD_POSTCOPY_RAM_LISTEN already has a listen thread");
> >          return -1;
> > --
> > 2.13.5
> >
> >
> 
> 
> Looks good to me otherwise,
> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

Thanks.

Dave

> 
> -- 
> Marc-André Lureau
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK