Re: [Qemu-devel] [PATCH v4 11/29] vhost+postcopy: Transmit 'listen' to client

["Marc-André Lureau" <marcandre.lureau@gmail.com>]

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>
>
> Notify the vhost-user client on reception of the 'postcopy-listen'
> event from the source.

minor nit, please change with "vhost-user slave", since that's the
terminology we use for vhost-user protocol. (server/client is for the
socket layer relation)

>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> Reviewed-by: Peter Xu <peterx@redhat.com>
> ---
>  contrib/libvhost-user/libvhost-user.c | 19 +++++++++++++++++++
>  contrib/libvhost-user/libvhost-user.h |  2 ++
>  docs/interop/vhost-user.txt           | 11 +++++++++++
>  hw/virtio/trace-events                |  3 +++
>  hw/virtio/vhost-user.c                | 34 ++++++++++++++++++++++++++++++++++
>  migration/postcopy-ram.h              |  1 +
>  migration/savevm.c                    |  7 +++++++
>  7 files changed, 77 insertions(+)
>
> diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c
> index 0b563fc5ae..beec7695a8 100644
> --- a/contrib/libvhost-user/libvhost-user.c
> +++ b/contrib/libvhost-user/libvhost-user.c
> @@ -98,6 +98,7 @@ vu_request_to_string(unsigned int req)
>          REQ(VHOST_USER_GET_CONFIG),
>          REQ(VHOST_USER_SET_CONFIG),
>          REQ(VHOST_USER_POSTCOPY_ADVISE),
> +        REQ(VHOST_USER_POSTCOPY_LISTEN),
>          REQ(VHOST_USER_MAX),
>      };
>  #undef REQ
> @@ -933,6 +934,22 @@ out:
>      return true; /* = send a reply */
>  }
>
> +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)
>  {
> @@ -1006,6 +1023,8 @@ 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 074b7860f6..ed505cf0c1 100644
> --- a/contrib/libvhost-user/libvhost-user.h
> +++ b/contrib/libvhost-user/libvhost-user.h
> @@ -86,6 +86,7 @@ typedef enum VhostUserRequest {
>      VHOST_USER_CREATE_CRYPTO_SESSION = 26,
>      VHOST_USER_CLOSE_CRYPTO_SESSION = 27,
>      VHOST_USER_POSTCOPY_ADVISE  = 28,
> +    VHOST_USER_POSTCOPY_LISTEN  = 29,
>      VHOST_USER_MAX
>  } VhostUserRequest;
>
> @@ -285,6 +286,7 @@ 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 acc4186c79..7cc7006ef3 100644
> --- a/docs/interop/vhost-user.txt
> +++ b/docs/interop/vhost-user.txt
> @@ -709,6 +709,17 @@ 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: 29
> +      Master payload: N/A
> +
> +      Master advises slave that a transition to postcopy mode has happened.
> +      The slave must ensure that shared memory is registered with userfaultfd
> +      to cause faulting of non-present pages.
> +
> +      This is always sent sometime after a VHOST_USER_POSTCOPY_ADVISE, and
> +      thus only when VHOST_USER_PROTOCOL_F_PAGEFAULT is supported.
> +
>  Slave message types
>  -------------------
>
> diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
> index 742ff0f90b..06ec03d6e7 100644
> --- a/hw/virtio/trace-events
> +++ b/hw/virtio/trace-events
> @@ -6,6 +6,9 @@ vhost_region_add_section(const char *name, uint64_t gpa, uint64_t size, uint64_t
>  vhost_region_add_section_abut(const char *name, uint64_t new_size) "%s: 0x%"PRIx64
>  vhost_section(const char *name, int r) "%s:%d"
>
> +# 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 9f74111e92..ee200f703e 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -20,6 +20,7 @@
>  #include "sysemu/cryptodev.h"
>  #include "migration/migration.h"
>  #include "migration/postcopy-ram.h"
> +#include "trace.h"
>
>  #include <sys/ioctl.h>
>  #include <sys/socket.h>
> @@ -79,6 +80,7 @@ typedef enum VhostUserRequest {
>      VHOST_USER_CREATE_CRYPTO_SESSION = 26,
>      VHOST_USER_CLOSE_CRYPTO_SESSION = 27,
>      VHOST_USER_POSTCOPY_ADVISE  = 28,
> +    VHOST_USER_POSTCOPY_LISTEN  = 29,
>      VHOST_USER_MAX
>  } VhostUserRequest;
>
> @@ -172,6 +174,8 @@ struct vhost_user {
>      int slave_fd;
>      NotifierWithReturn postcopy_notifier;
>      struct PostCopyFD  postcopy_fd;
> +    /* True once we've entered postcopy_listen */
> +    bool               postcopy_listen;
>  };
>
>  static bool ioeventfd_enabled(void)
> @@ -858,6 +862,33 @@ 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)
> +{
> +    struct vhost_user *u = dev->opaque;
> +    int ret;
> +    VhostUserMsg msg = {
> +        .hdr.request = VHOST_USER_POSTCOPY_LISTEN,
> +        .hdr.flags = VHOST_USER_VERSION | VHOST_USER_NEED_REPLY_MASK,
> +    };
> +    u->postcopy_listen = true;
> +    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)
>  {
> @@ -880,6 +911,9 @@ 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 f21eef6702..c8ced3470b 100644
> --- a/migration/postcopy-ram.h
> +++ b/migration/postcopy-ram.h
> @@ -131,6 +131,7 @@ 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 1f2bf12a28..305c3ceaf5 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -1618,6 +1618,8 @@ 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;
> @@ -1643,6 +1645,11 @@ static int loadvm_postcopy_handle_listen(MigrationIncomingState *mis)
>          }
>      }
>
> +    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;
> --
> 2.14.3
>
>



-- 
Marc-André Lureau