[Qemu-devel] [PATCH v4 06/29] vhost-user: Add 'VHOST_USER_POSTCOPY_ADVISE' message

Dr. David Alan Gilbert (git) posted 29 patches 7 years, 11 months ago
There is a newer version of this series
[Qemu-devel] [PATCH v4 06/29] vhost-user: Add 'VHOST_USER_POSTCOPY_ADVISE' message
Posted by Dr. David Alan Gilbert (git) 7 years, 11 months ago
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Wire up a notifier to send a VHOST_USER_POSTCOPY_ADVISE
message on an incoming advise.

Later patches will fill in the behaviour/contents of the
message.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 contrib/libvhost-user/libvhost-user.c | 14 ++++++++++
 contrib/libvhost-user/libvhost-user.h |  3 +++
 docs/interop/vhost-user.txt           | 10 ++++++++
 hw/virtio/vhost-user.c                | 48 +++++++++++++++++++++++++++++++++++
 migration/postcopy-ram.h              |  1 +
 migration/savevm.c                    |  6 +++++
 6 files changed, 82 insertions(+)

diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c
index 2e358b5bce..71825d2dde 100644
--- a/contrib/libvhost-user/libvhost-user.c
+++ b/contrib/libvhost-user/libvhost-user.c
@@ -86,6 +86,7 @@ vu_request_to_string(unsigned int req)
         REQ(VHOST_USER_SET_VRING_ENDIAN),
         REQ(VHOST_USER_GET_CONFIG),
         REQ(VHOST_USER_SET_CONFIG),
+        REQ(VHOST_USER_POSTCOPY_ADVISE),
         REQ(VHOST_USER_MAX),
     };
 #undef REQ
@@ -856,6 +857,17 @@ vu_set_config(VuDev *dev, VhostUserMsg *vmsg)
     return false;
 }
 
+static bool
+vu_set_postcopy_advise(VuDev *dev, VhostUserMsg *vmsg)
+{
+    /* TODO: Open ufd, pass it back in the request
+     * TODO: Add addresses
+     */
+    vmsg->payload.u64 = 0xcafe;
+    vmsg->size = sizeof(vmsg->payload.u64);
+    return true; /* = send a reply */
+}
+
 static bool
 vu_process_message(VuDev *dev, VhostUserMsg *vmsg)
 {
@@ -927,6 +939,8 @@ vu_process_message(VuDev *dev, VhostUserMsg *vmsg)
         return vu_set_config(dev, vmsg);
     case VHOST_USER_NONE:
         break;
+    case VHOST_USER_POSTCOPY_ADVISE:
+        return vu_set_postcopy_advise(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 96db29c4ce..00d78a8810 100644
--- a/contrib/libvhost-user/libvhost-user.h
+++ b/contrib/libvhost-user/libvhost-user.h
@@ -83,6 +83,9 @@ typedef enum VhostUserRequest {
     VHOST_USER_SET_VRING_ENDIAN = 23,
     VHOST_USER_GET_CONFIG = 24,
     VHOST_USER_SET_CONFIG = 25,
+    VHOST_USER_CREATE_CRYPTO_SESSION = 26,
+    VHOST_USER_CLOSE_CRYPTO_SESSION = 27,
+    VHOST_USER_POSTCOPY_ADVISE  = 28,
     VHOST_USER_MAX
 } VhostUserRequest;
 
diff --git a/docs/interop/vhost-user.txt b/docs/interop/vhost-user.txt
index 91a572d781..acc4186c79 100644
--- a/docs/interop/vhost-user.txt
+++ b/docs/interop/vhost-user.txt
@@ -699,6 +699,16 @@ Master message types
      feature has been successfully negotiated.
      It's a required feature for crypto devices.
 
+ * VHOST_USER_POSTCOPY_ADVISE
+      Id: 28
+      Master payload: N/A
+      Slave payload: userfault fd + u64
+
+      When VHOST_USER_PROTOCOL_F_PAGEFAULT is supported, the
+      master advises slave that a migration with postcopy enabled is underway,
+      the slave must open a userfaultfd for later use.
+      Note that at this stage the migration is still in precopy mode.
+
 Slave message types
 -------------------
 
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index aab35c4845..431858b219 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -78,6 +78,7 @@ typedef enum VhostUserRequest {
     VHOST_USER_SET_CONFIG = 25,
     VHOST_USER_CREATE_CRYPTO_SESSION = 26,
     VHOST_USER_CLOSE_CRYPTO_SESSION = 27,
+    VHOST_USER_POSTCOPY_ADVISE  = 28,
     VHOST_USER_MAX
 } VhostUserRequest;
 
@@ -795,6 +796,50 @@ out:
     return ret;
 }
 
+/*
+ * Called at the start of an inbound postcopy on reception of the
+ * 'advise' command.
+ */
+static int vhost_user_postcopy_advise(struct vhost_dev *dev, Error **errp)
+{
+    struct vhost_user *u = dev->opaque;
+    CharBackend *chr = u->chr;
+    int ufd;
+    VhostUserMsg msg = {
+        .hdr.request = VHOST_USER_POSTCOPY_ADVISE,
+        .hdr.flags = VHOST_USER_VERSION,
+    };
+
+    if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
+        error_setg(errp, "Failed to send postcopy_advise to vhost");
+        return -1;
+    }
+
+    if (vhost_user_read(dev, &msg) < 0) {
+        error_setg(errp, "Failed to get postcopy_advise reply from vhost");
+        return -1;
+    }
+
+    if (msg.hdr.request != VHOST_USER_POSTCOPY_ADVISE) {
+        error_setg(errp, "Unexpected msg type. Expected %d received %d",
+                     VHOST_USER_POSTCOPY_ADVISE, msg.hdr.request);
+        return -1;
+    }
+
+    if (msg.hdr.size != sizeof(msg.payload.u64)) {
+        error_setg(errp, "Received bad msg size.");
+        return -1;
+    }
+    ufd = qemu_chr_fe_get_msgfd(chr);
+    if (ufd < 0) {
+        error_setg(errp, "%s: Failed to get ufd", __func__);
+        return -1;
+    }
+
+    /* TODO: register ufd with userfault thread */
+    return 0;
+}
+
 static int vhost_user_postcopy_notifier(NotifierWithReturn *notifier,
                                         void *opaque)
 {
@@ -814,6 +859,9 @@ static int vhost_user_postcopy_notifier(NotifierWithReturn *notifier,
         }
         break;
 
+    case POSTCOPY_NOTIFY_INBOUND_ADVISE:
+        return vhost_user_postcopy_advise(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 2e879bbacb..0421c98d57 100644
--- a/migration/postcopy-ram.h
+++ b/migration/postcopy-ram.h
@@ -130,6 +130,7 @@ void postcopy_infrastructure_init(void);
  */
 enum PostcopyNotifyReason {
     POSTCOPY_NOTIFY_PROBE = 0,
+    POSTCOPY_NOTIFY_INBOUND_ADVISE,
 };
 
 struct PostcopyNotifyData {
diff --git a/migration/savevm.c b/migration/savevm.c
index 358c5b51e2..1f2bf12a28 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1386,6 +1386,7 @@ static int loadvm_postcopy_handle_advise(MigrationIncomingState *mis,
 {
     PostcopyState ps = postcopy_state_set(POSTCOPY_INCOMING_ADVISE);
     uint64_t remote_pagesize_summary, local_pagesize_summary, remote_tps;
+    Error *local_err = NULL;
 
     trace_loadvm_postcopy_handle_advise();
     if (ps != POSTCOPY_INCOMING_NONE) {
@@ -1451,6 +1452,11 @@ static int loadvm_postcopy_handle_advise(MigrationIncomingState *mis,
         return -1;
     }
 
+    if (postcopy_notify(POSTCOPY_NOTIFY_INBOUND_ADVISE, &local_err)) {
+        error_report_err(local_err);
+        return -1;
+    }
+
     if (ram_postcopy_incoming_init(mis)) {
         return -1;
     }
-- 
2.14.3


Re: [Qemu-devel] [PATCH v4 06/29] vhost-user: Add 'VHOST_USER_POSTCOPY_ADVISE' message
Posted by Marc-André Lureau 7 years, 11 months ago
Hi

On Thu, Mar 8, 2018 at 8:57 PM, Dr. David Alan Gilbert (git)
<dgilbert@redhat.com> wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>
> Wire up a notifier to send a VHOST_USER_POSTCOPY_ADVISE
> message on an incoming advise.
>
> Later patches will fill in the behaviour/contents of the
> message.
>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  contrib/libvhost-user/libvhost-user.c | 14 ++++++++++
>  contrib/libvhost-user/libvhost-user.h |  3 +++
>  docs/interop/vhost-user.txt           | 10 ++++++++
>  hw/virtio/vhost-user.c                | 48 +++++++++++++++++++++++++++++++++++
>  migration/postcopy-ram.h              |  1 +
>  migration/savevm.c                    |  6 +++++
>  6 files changed, 82 insertions(+)
>
> diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c
> index 2e358b5bce..71825d2dde 100644
> --- a/contrib/libvhost-user/libvhost-user.c
> +++ b/contrib/libvhost-user/libvhost-user.c
> @@ -86,6 +86,7 @@ vu_request_to_string(unsigned int req)
>          REQ(VHOST_USER_SET_VRING_ENDIAN),
>          REQ(VHOST_USER_GET_CONFIG),
>          REQ(VHOST_USER_SET_CONFIG),
> +        REQ(VHOST_USER_POSTCOPY_ADVISE),
>          REQ(VHOST_USER_MAX),
>      };
>  #undef REQ
> @@ -856,6 +857,17 @@ vu_set_config(VuDev *dev, VhostUserMsg *vmsg)
>      return false;
>  }
>
> +static bool
> +vu_set_postcopy_advise(VuDev *dev, VhostUserMsg *vmsg)
> +{
> +    /* TODO: Open ufd, pass it back in the request
> +     * TODO: Add addresses
> +     */
> +    vmsg->payload.u64 = 0xcafe;
> +    vmsg->size = sizeof(vmsg->payload.u64);

Left over? Why send back a u64 with 0xcafe value?

> +    return true; /* = send a reply */
> +}
> +
>  static bool
>  vu_process_message(VuDev *dev, VhostUserMsg *vmsg)
>  {
> @@ -927,6 +939,8 @@ vu_process_message(VuDev *dev, VhostUserMsg *vmsg)
>          return vu_set_config(dev, vmsg);
>      case VHOST_USER_NONE:
>          break;
> +    case VHOST_USER_POSTCOPY_ADVISE:
> +        return vu_set_postcopy_advise(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 96db29c4ce..00d78a8810 100644
> --- a/contrib/libvhost-user/libvhost-user.h
> +++ b/contrib/libvhost-user/libvhost-user.h
> @@ -83,6 +83,9 @@ typedef enum VhostUserRequest {
>      VHOST_USER_SET_VRING_ENDIAN = 23,
>      VHOST_USER_GET_CONFIG = 24,
>      VHOST_USER_SET_CONFIG = 25,
> +    VHOST_USER_CREATE_CRYPTO_SESSION = 26,
> +    VHOST_USER_CLOSE_CRYPTO_SESSION = 27,
> +    VHOST_USER_POSTCOPY_ADVISE  = 28,
>      VHOST_USER_MAX
>  } VhostUserRequest;
>
> diff --git a/docs/interop/vhost-user.txt b/docs/interop/vhost-user.txt
> index 91a572d781..acc4186c79 100644
> --- a/docs/interop/vhost-user.txt
> +++ b/docs/interop/vhost-user.txt
> @@ -699,6 +699,16 @@ Master message types
>       feature has been successfully negotiated.
>       It's a required feature for crypto devices.
>
> + * VHOST_USER_POSTCOPY_ADVISE
> +      Id: 28
> +      Master payload: N/A
> +      Slave payload: userfault fd + u64

If the reply is modified, update doc as well

> +
> +      When VHOST_USER_PROTOCOL_F_PAGEFAULT is supported, the
> +      master advises slave that a migration with postcopy enabled is underway,
> +      the slave must open a userfaultfd for later use.
> +      Note that at this stage the migration is still in precopy mode.
> +
>  Slave message types
>  -------------------
>
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index aab35c4845..431858b219 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -78,6 +78,7 @@ typedef enum VhostUserRequest {
>      VHOST_USER_SET_CONFIG = 25,
>      VHOST_USER_CREATE_CRYPTO_SESSION = 26,
>      VHOST_USER_CLOSE_CRYPTO_SESSION = 27,
> +    VHOST_USER_POSTCOPY_ADVISE  = 28,
>      VHOST_USER_MAX
>  } VhostUserRequest;
>
> @@ -795,6 +796,50 @@ out:
>      return ret;
>  }
>
> +/*
> + * Called at the start of an inbound postcopy on reception of the
> + * 'advise' command.
> + */
> +static int vhost_user_postcopy_advise(struct vhost_dev *dev, Error **errp)
> +{
> +    struct vhost_user *u = dev->opaque;
> +    CharBackend *chr = u->chr;
> +    int ufd;
> +    VhostUserMsg msg = {
> +        .hdr.request = VHOST_USER_POSTCOPY_ADVISE,
> +        .hdr.flags = VHOST_USER_VERSION,
> +    };
> +
> +    if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
> +        error_setg(errp, "Failed to send postcopy_advise to vhost");
> +        return -1;
> +    }
> +
> +    if (vhost_user_read(dev, &msg) < 0) {
> +        error_setg(errp, "Failed to get postcopy_advise reply from vhost");
> +        return -1;
> +    }
> +
> +    if (msg.hdr.request != VHOST_USER_POSTCOPY_ADVISE) {
> +        error_setg(errp, "Unexpected msg type. Expected %d received %d",
> +                     VHOST_USER_POSTCOPY_ADVISE, msg.hdr.request);
> +        return -1;
> +    }
> +
> +    if (msg.hdr.size != sizeof(msg.payload.u64)) {
> +        error_setg(errp, "Received bad msg size.");
> +        return -1;
> +    }
> +    ufd = qemu_chr_fe_get_msgfd(chr);
> +    if (ufd < 0) {
> +        error_setg(errp, "%s: Failed to get ufd", __func__);
> +        return -1;
> +    }
> +
> +    /* TODO: register ufd with userfault thread */
> +    return 0;
> +}
> +
>  static int vhost_user_postcopy_notifier(NotifierWithReturn *notifier,
>                                          void *opaque)
>  {
> @@ -814,6 +859,9 @@ static int vhost_user_postcopy_notifier(NotifierWithReturn *notifier,
>          }
>          break;
>
> +    case POSTCOPY_NOTIFY_INBOUND_ADVISE:
> +        return vhost_user_postcopy_advise(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 2e879bbacb..0421c98d57 100644
> --- a/migration/postcopy-ram.h
> +++ b/migration/postcopy-ram.h
> @@ -130,6 +130,7 @@ void postcopy_infrastructure_init(void);
>   */
>  enum PostcopyNotifyReason {
>      POSTCOPY_NOTIFY_PROBE = 0,
> +    POSTCOPY_NOTIFY_INBOUND_ADVISE,
>  };
>
>  struct PostcopyNotifyData {
> diff --git a/migration/savevm.c b/migration/savevm.c
> index 358c5b51e2..1f2bf12a28 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -1386,6 +1386,7 @@ static int loadvm_postcopy_handle_advise(MigrationIncomingState *mis,
>  {
>      PostcopyState ps = postcopy_state_set(POSTCOPY_INCOMING_ADVISE);
>      uint64_t remote_pagesize_summary, local_pagesize_summary, remote_tps;
> +    Error *local_err = NULL;
>
>      trace_loadvm_postcopy_handle_advise();
>      if (ps != POSTCOPY_INCOMING_NONE) {
> @@ -1451,6 +1452,11 @@ static int loadvm_postcopy_handle_advise(MigrationIncomingState *mis,
>          return -1;
>      }
>
> +    if (postcopy_notify(POSTCOPY_NOTIFY_INBOUND_ADVISE, &local_err)) {
> +        error_report_err(local_err);
> +        return -1;
> +    }
> +
>      if (ram_postcopy_incoming_init(mis)) {
>          return -1;
>      }
> --
> 2.14.3
>
>



-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v4 06/29] vhost-user: Add 'VHOST_USER_POSTCOPY_ADVISE' message
Posted by Dr. David Alan Gilbert 7 years, 11 months ago
* Marc-André Lureau (marcandre.lureau@gmail.com) wrote:
> Hi
> 
> On Thu, Mar 8, 2018 at 8:57 PM, Dr. David Alan Gilbert (git)
> <dgilbert@redhat.com> wrote:
> > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> >
> > Wire up a notifier to send a VHOST_USER_POSTCOPY_ADVISE
> > message on an incoming advise.
> >
> > Later patches will fill in the behaviour/contents of the
> > message.
> >
> > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> > ---
> >  contrib/libvhost-user/libvhost-user.c | 14 ++++++++++
> >  contrib/libvhost-user/libvhost-user.h |  3 +++
> >  docs/interop/vhost-user.txt           | 10 ++++++++
> >  hw/virtio/vhost-user.c                | 48 +++++++++++++++++++++++++++++++++++
> >  migration/postcopy-ram.h              |  1 +
> >  migration/savevm.c                    |  6 +++++
> >  6 files changed, 82 insertions(+)
> >
> > diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c
> > index 2e358b5bce..71825d2dde 100644
> > --- a/contrib/libvhost-user/libvhost-user.c
> > +++ b/contrib/libvhost-user/libvhost-user.c
> > @@ -86,6 +86,7 @@ vu_request_to_string(unsigned int req)
> >          REQ(VHOST_USER_SET_VRING_ENDIAN),
> >          REQ(VHOST_USER_GET_CONFIG),
> >          REQ(VHOST_USER_SET_CONFIG),
> > +        REQ(VHOST_USER_POSTCOPY_ADVISE),
> >          REQ(VHOST_USER_MAX),
> >      };
> >  #undef REQ
> > @@ -856,6 +857,17 @@ vu_set_config(VuDev *dev, VhostUserMsg *vmsg)
> >      return false;
> >  }
> >
> > +static bool
> > +vu_set_postcopy_advise(VuDev *dev, VhostUserMsg *vmsg)
> > +{
> > +    /* TODO: Open ufd, pass it back in the request
> > +     * TODO: Add addresses
> > +     */
> > +    vmsg->payload.u64 = 0xcafe;
> > +    vmsg->size = sizeof(vmsg->payload.u64);
> 
> Left over? Why send back a u64 with 0xcafe value?

I think because I didn't realise it could be an empty reply;  OK, v5
coming up with that removed once we're done with this set.

> > +    return true; /* = send a reply */
> > +}
> > +
> >  static bool
> >  vu_process_message(VuDev *dev, VhostUserMsg *vmsg)
> >  {
> > @@ -927,6 +939,8 @@ vu_process_message(VuDev *dev, VhostUserMsg *vmsg)
> >          return vu_set_config(dev, vmsg);
> >      case VHOST_USER_NONE:
> >          break;
> > +    case VHOST_USER_POSTCOPY_ADVISE:
> > +        return vu_set_postcopy_advise(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 96db29c4ce..00d78a8810 100644
> > --- a/contrib/libvhost-user/libvhost-user.h
> > +++ b/contrib/libvhost-user/libvhost-user.h
> > @@ -83,6 +83,9 @@ typedef enum VhostUserRequest {
> >      VHOST_USER_SET_VRING_ENDIAN = 23,
> >      VHOST_USER_GET_CONFIG = 24,
> >      VHOST_USER_SET_CONFIG = 25,
> > +    VHOST_USER_CREATE_CRYPTO_SESSION = 26,
> > +    VHOST_USER_CLOSE_CRYPTO_SESSION = 27,
> > +    VHOST_USER_POSTCOPY_ADVISE  = 28,
> >      VHOST_USER_MAX
> >  } VhostUserRequest;
> >
> > diff --git a/docs/interop/vhost-user.txt b/docs/interop/vhost-user.txt
> > index 91a572d781..acc4186c79 100644
> > --- a/docs/interop/vhost-user.txt
> > +++ b/docs/interop/vhost-user.txt
> > @@ -699,6 +699,16 @@ Master message types
> >       feature has been successfully negotiated.
> >       It's a required feature for crypto devices.
> >
> > + * VHOST_USER_POSTCOPY_ADVISE
> > +      Id: 28
> > +      Master payload: N/A
> > +      Slave payload: userfault fd + u64
> 
> If the reply is modified, update doc as well
> 
> > +
> > +      When VHOST_USER_PROTOCOL_F_PAGEFAULT is supported, the
> > +      master advises slave that a migration with postcopy enabled is underway,
> > +      the slave must open a userfaultfd for later use.
> > +      Note that at this stage the migration is still in precopy mode.
> > +
> >  Slave message types
> >  -------------------
> >
> > diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> > index aab35c4845..431858b219 100644
> > --- a/hw/virtio/vhost-user.c
> > +++ b/hw/virtio/vhost-user.c
> > @@ -78,6 +78,7 @@ typedef enum VhostUserRequest {
> >      VHOST_USER_SET_CONFIG = 25,
> >      VHOST_USER_CREATE_CRYPTO_SESSION = 26,
> >      VHOST_USER_CLOSE_CRYPTO_SESSION = 27,
> > +    VHOST_USER_POSTCOPY_ADVISE  = 28,
> >      VHOST_USER_MAX
> >  } VhostUserRequest;
> >
> > @@ -795,6 +796,50 @@ out:
> >      return ret;
> >  }
> >
> > +/*
> > + * Called at the start of an inbound postcopy on reception of the
> > + * 'advise' command.
> > + */
> > +static int vhost_user_postcopy_advise(struct vhost_dev *dev, Error **errp)
> > +{
> > +    struct vhost_user *u = dev->opaque;
> > +    CharBackend *chr = u->chr;
> > +    int ufd;
> > +    VhostUserMsg msg = {
> > +        .hdr.request = VHOST_USER_POSTCOPY_ADVISE,
> > +        .hdr.flags = VHOST_USER_VERSION,
> > +    };
> > +
> > +    if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
> > +        error_setg(errp, "Failed to send postcopy_advise to vhost");
> > +        return -1;
> > +    }
> > +
> > +    if (vhost_user_read(dev, &msg) < 0) {
> > +        error_setg(errp, "Failed to get postcopy_advise reply from vhost");
> > +        return -1;
> > +    }
> > +
> > +    if (msg.hdr.request != VHOST_USER_POSTCOPY_ADVISE) {
> > +        error_setg(errp, "Unexpected msg type. Expected %d received %d",
> > +                     VHOST_USER_POSTCOPY_ADVISE, msg.hdr.request);
> > +        return -1;
> > +    }
> > +
> > +    if (msg.hdr.size != sizeof(msg.payload.u64)) {
> > +        error_setg(errp, "Received bad msg size.");
> > +        return -1;
> > +    }
> > +    ufd = qemu_chr_fe_get_msgfd(chr);
> > +    if (ufd < 0) {
> > +        error_setg(errp, "%s: Failed to get ufd", __func__);
> > +        return -1;
> > +    }
> > +
> > +    /* TODO: register ufd with userfault thread */
> > +    return 0;
> > +}
> > +
> >  static int vhost_user_postcopy_notifier(NotifierWithReturn *notifier,
> >                                          void *opaque)
> >  {
> > @@ -814,6 +859,9 @@ static int vhost_user_postcopy_notifier(NotifierWithReturn *notifier,
> >          }
> >          break;
> >
> > +    case POSTCOPY_NOTIFY_INBOUND_ADVISE:
> > +        return vhost_user_postcopy_advise(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 2e879bbacb..0421c98d57 100644
> > --- a/migration/postcopy-ram.h
> > +++ b/migration/postcopy-ram.h
> > @@ -130,6 +130,7 @@ void postcopy_infrastructure_init(void);
> >   */
> >  enum PostcopyNotifyReason {
> >      POSTCOPY_NOTIFY_PROBE = 0,
> > +    POSTCOPY_NOTIFY_INBOUND_ADVISE,
> >  };
> >
> >  struct PostcopyNotifyData {
> > diff --git a/migration/savevm.c b/migration/savevm.c
> > index 358c5b51e2..1f2bf12a28 100644
> > --- a/migration/savevm.c
> > +++ b/migration/savevm.c
> > @@ -1386,6 +1386,7 @@ static int loadvm_postcopy_handle_advise(MigrationIncomingState *mis,
> >  {
> >      PostcopyState ps = postcopy_state_set(POSTCOPY_INCOMING_ADVISE);
> >      uint64_t remote_pagesize_summary, local_pagesize_summary, remote_tps;
> > +    Error *local_err = NULL;
> >
> >      trace_loadvm_postcopy_handle_advise();
> >      if (ps != POSTCOPY_INCOMING_NONE) {
> > @@ -1451,6 +1452,11 @@ static int loadvm_postcopy_handle_advise(MigrationIncomingState *mis,
> >          return -1;
> >      }
> >
> > +    if (postcopy_notify(POSTCOPY_NOTIFY_INBOUND_ADVISE, &local_err)) {
> > +        error_report_err(local_err);
> > +        return -1;
> > +    }
> > +
> >      if (ram_postcopy_incoming_init(mis)) {
> >          return -1;
> >      }
> > --
> > 2.14.3
> >
> >
> 
> 
> 
> -- 
> Marc-André Lureau
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK