Re: [Qemu-devel] [PATCH] vhost-user: Don't ask for reply on postcopy mem table set

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

* Ilya Maximets (i.maximets@samsung.com) wrote:
> According to documentation, NEED_REPLY_MASK should not be set
> for VHOST_USER_SET_MEM_TABLE request in postcopy mode.
> This restriction was mistakenly applied to 'reply_supported'
> variable, which is local and used only for non-postcopy case.
> 
> CC: Dr. David Alan Gilbert <dgilbert@redhat.com>
> Fixes: 9bb38019942c ("vhost+postcopy: Send address back to qemu")
> Signed-off-by: Ilya Maximets <i.maximets@samsung.com>

Yes I think that's right;   the 2nd part (in vhost_user_set_mem_table)
is easy; that's just left overs from before I split it into two.


The postcopy side we've already got the reply from the client
with the mappings, and now we've sent the OK at the end;
so there's no need for the final reply.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> ---
>  hw/virtio/vhost-user.c | 13 +------------
>  1 file changed, 1 insertion(+), 12 deletions(-)
> 
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index b041343632..c442daa562 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -374,8 +374,6 @@ static int vhost_user_set_mem_table_postcopy(struct vhost_dev *dev,
>      int fds[VHOST_MEMORY_MAX_NREGIONS];
>      int i, fd;
>      size_t fd_num = 0;
> -    bool reply_supported = virtio_has_feature(dev->protocol_features,
> -                                              VHOST_USER_PROTOCOL_F_REPLY_ACK);
>      VhostUserMsg msg_reply;
>      int region_i, msg_i;
>  
> @@ -384,10 +382,6 @@ static int vhost_user_set_mem_table_postcopy(struct vhost_dev *dev,
>          .hdr.flags = VHOST_USER_VERSION,
>      };
>  
> -    if (reply_supported) {
> -        msg.hdr.flags |= VHOST_USER_NEED_REPLY_MASK;
> -    }
> -
>      if (u->region_rb_len < dev->mem->nregions) {
>          u->region_rb = g_renew(RAMBlock*, u->region_rb, dev->mem->nregions);
>          u->region_rb_offset = g_renew(ram_addr_t, u->region_rb_offset,
> @@ -503,10 +497,6 @@ static int vhost_user_set_mem_table_postcopy(struct vhost_dev *dev,
>          return -1;
>      }
>  
> -    if (reply_supported) {
> -        return process_message_reply(dev, &msg);
> -    }
> -
>      return 0;
>  }
>  
> @@ -519,8 +509,7 @@ static int vhost_user_set_mem_table(struct vhost_dev *dev,
>      size_t fd_num = 0;
>      bool do_postcopy = u->postcopy_listen && u->postcopy_fd.handler;
>      bool reply_supported = virtio_has_feature(dev->protocol_features,
> -                                          VHOST_USER_PROTOCOL_F_REPLY_ACK) &&
> -                                          !do_postcopy;
> +                                              VHOST_USER_PROTOCOL_F_REPLY_ACK);
>  
>      if (do_postcopy) {
>          /* Postcopy has enough differences that it's best done in it's own
> -- 
> 2.17.1
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK