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

[Marc-André Lureau]

On Thu, Aug 24, 2017 at 12:27 PM, Dr. David Alan Gilbert (git)
<address@hidden> wrote:
> From: "Dr. David Alan Gilbert" <address@hidden>
>
> Notify the vhost-user client on reception of the 'postcopy-listen'
> event from the source.
>
> Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> ---
>  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

>  #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 <address@hidden>


-- 
Marc-André Lureau