Re: [dpdk-dev] [PATCH v5 1/8] lib/librte_vhost: add external backend support

[Maxime Coquelin <maxime.coquelin@redhat.com>]

Hi,

I think the title should change, as it makes to think it could be used 
by external backends that doesn't live in the librte_vhost directory.

One more comment below, otherwise that looks good to me.

Thanks,
Maxime

On 04/04/2018 12:08 PM, Fan Zhang wrote:
> This patch adds external backend support to vhost library. The patch provides
> new function prototypes for the external backend to register pre and post
> vhost-user message handlers.
> 
> Signed-off-by: Fan Zhang <roy.fan.zhang@intel.com>
> ---
>   lib/librte_vhost/vhost.c      |  2 +-
>   lib/librte_vhost/vhost.h      | 53 +++++++++++++++++++++++++++++++++++++++++--
>   lib/librte_vhost/vhost_user.c | 31 ++++++++++++++++++++++++-
>   3 files changed, 82 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
> index f6f12a03b..99f8b01fb 100644
> --- a/lib/librte_vhost/vhost.c
> +++ b/lib/librte_vhost/vhost.c
> @@ -1,5 +1,5 @@
>   /* SPDX-License-Identifier: BSD-3-Clause
> - * Copyright(c) 2010-2016 Intel Corporation
> + * Copyright(c) 2010-2017 Intel Corporation
>    */
>   
>   #include <linux/vhost.h>
> diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
> index 4981e6d0c..f28164849 100644
> --- a/lib/librte_vhost/vhost.h
> +++ b/lib/librte_vhost/vhost.h
> @@ -1,5 +1,5 @@
>   /* SPDX-License-Identifier: BSD-3-Clause
> - * Copyright(c) 2010-2014 Intel Corporation
> + * Copyright(c) 2010-2018 Intel Corporation
>    */
>   
>   #ifndef _VHOST_NET_CDEV_H_
> @@ -211,6 +211,51 @@ struct guest_page {
>   };
>   
>   /**
> + * function prototype for the vhost backend to handler specific vhost user
> + * messages prior to the master message handling
> + *
> + * @param vid
> + *  vhost device id
> + * @param msg
> + *  Message pointer.
> + * @param require_reply
> + *  If the handler requires sending a reply, this varaible shall be written 1,
> + *  otherwise 0.
> + * @param skip_master
> + *  If the handler requires skipping the master message handling, this variable
> + *  shall be written 1, otherwise 0.
> + * @return
> + *  0 on success, -1 on failure
> + */
> +typedef int (*rte_vhost_msg_pre_handle)(int vid, void *msg,
> +		uint32_t *require_reply, uint32_t *skip_master);
Also, please remove the rte_ prefix here and evrywhere else as it is
purely vhost lib internal for now.

> +
> +/**
> + * function prototype for the vhost backend to handler specific vhost user
> + * messages after the master message handling is done
> + *
> + * @param vid
> + *  vhost device id
> + * @param msg
> + *  Message pointer.
> + * @param require_reply
> + *  If the handler requires sending a reply, this varaible shall be written 1,
> + *  otherwise 0.
> + * @return
> + *  0 on success, -1 on failure
> + */
> +typedef int (*rte_vhost_msg_post_handle)(int vid, void *msg,
> +		uint32_t *require_reply);
> +
> +/**
> + * pre and post vhost user message handlers
> + */
> +struct vhost_user_extern_ops {
> +	rte_vhost_msg_pre_handle pre_msg_handle;
> +	rte_vhost_msg_post_handle post_msg_handle;
> +};
> +
> +/**
>    * Device structure contains all configuration information relating
>    * to the device.
>    */
> @@ -242,8 +287,12 @@ struct virtio_net {
>   	struct guest_page       *guest_pages;
>   
>   	int			slave_req_fd;
> -} __rte_cache_aligned;
>   
> +	/* private data for external virtio device */
> +	void			*extern_data;
> +	/* pre and post vhost user message handlers for externel backend */
> +	struct vhost_user_extern_ops extern_ops;
> +} __rte_cache_aligned;
>   
>   #define VHOST_LOG_PAGE	4096
>   
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index 66e1b82a5..a435cce17 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -1,5 +1,5 @@
>   /* SPDX-License-Identifier: BSD-3-Clause
> - * Copyright(c) 2010-2016 Intel Corporation
> + * Copyright(c) 2010-2018 Intel Corporation
>    */
>   
>   /* Security model
> @@ -1379,6 +1379,7 @@ vhost_user_msg_handler(int vid, int fd)
>   	struct VhostUserMsg msg;
>   	int ret;
>   	int unlock_required = 0;
> +	uint32_t skip_master = 0;
>   
>   	dev = get_device(vid);
>   	if (dev == NULL)
> @@ -1456,6 +1457,21 @@ vhost_user_msg_handler(int vid, int fd)
>   
>   	}
>   
> +	if (dev->extern_ops.pre_msg_handle) {
> +		uint32_t need_reply;
> +
> +		ret = (*dev->extern_ops.pre_msg_handle)(dev->vid,
> +				(void *)&msg, &need_reply, &skip_master);
> +		if (ret < 0)
> +			goto skip_to_reply;
> +
> +		if (need_reply)
> +			send_vhost_reply(fd, &msg);
> +
> +		if (skip_master)
> +			goto skip_to_post_handle;
> +	}
> +
>   	switch (msg.request.master) {
>   	case VHOST_USER_GET_FEATURES:
>   		msg.payload.u64 = vhost_user_get_features(dev);
> @@ -1556,9 +1572,22 @@ vhost_user_msg_handler(int vid, int fd)
>   	default:
>   		ret = -1;
>   		break;
> +	}
> +
> +skip_to_post_handle:
> +	if (dev->extern_ops.post_msg_handle) {
> +		uint32_t need_reply;
> +
> +		ret = (*dev->extern_ops.post_msg_handle)(
> +				dev->vid, (void *)&msg, &need_reply);
> +		if (ret < 0)
> +			goto skip_to_reply;
>   
> +		if (need_reply)
> +			send_vhost_reply(fd, &msg);
>   	}
>   
> +skip_to_reply:
>   	if (unlock_required)
>   		vhost_user_unlock_all_queue_pairs(dev);
>   
>