Re: [dpdk-dev] [PATCH 05/21] vhost: add support to slave requests channel

[Tiwei Bie <tiwei.bie@intel.com>]

On Thu, Aug 31, 2017 at 11:50:07AM +0200, Maxime Coquelin wrote:
> Currently, only QEMU sends requests, the backend sends
> replies. In some cases, the backend may need to send
> requests to QEMU, like IOTLB miss events when IOMMU is
> supported.
> 
> This patch introduces a new channel for such requests.
> QEMU sends a file descriptor of a new socket using
> VHOST_USER_SET_SLAVE_REQ_FD.
> 
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> ---
>  lib/librte_vhost/vhost.h      |  2 ++
>  lib/librte_vhost/vhost_user.c | 27 +++++++++++++++++++++++++++
>  lib/librte_vhost/vhost_user.h | 10 +++++++++-
>  3 files changed, 38 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
> index 18ad69c85..2340b0c2a 100644
> --- a/lib/librte_vhost/vhost.h
> +++ b/lib/librte_vhost/vhost.h
> @@ -196,6 +196,8 @@ struct virtio_net {
>  	uint32_t		nr_guest_pages;
>  	uint32_t		max_guest_pages;
>  	struct guest_page       *guest_pages;
> +
> +	int			slave_req_fd;
>  } __rte_cache_aligned;
>  
>  
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index 8984dcb6a..7b3c2f32a 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -76,6 +76,7 @@ static const char *vhost_message_str[VHOST_USER_MAX] = {
>  	[VHOST_USER_SET_VRING_ENABLE]  = "VHOST_USER_SET_VRING_ENABLE",
>  	[VHOST_USER_SEND_RARP]  = "VHOST_USER_SEND_RARP",
>  	[VHOST_USER_NET_SET_MTU]  = "VHOST_USER_NET_SET_MTU",
> +	[VHOST_USER_SET_SLAVE_REQ_FD]  = "VHOST_USER_SET_SLAVE_REQ_FD",
>  };
>  
>  static uint64_t
> @@ -122,6 +123,11 @@ vhost_backend_cleanup(struct virtio_net *dev)
>  		munmap((void *)(uintptr_t)dev->log_addr, dev->log_size);
>  		dev->log_addr = 0;
>  	}
> +
> +	if (dev->slave_req_fd >= 0) {
> +		close(dev->slave_req_fd);
> +		dev->slave_req_fd = -1;

The slave_req_fd should also be initialized to -1 when allocating
the virtio_net structure. Currently, it's missing.

Best regards,
Tiwei Bie