Re: [dpdk-dev] [PATCH v3 6/8] vhost: add support for virtio get status message

["Xia, Chenbo" <chenbo.xia@intel.com>]

> -----Original Message-----
> From: Adrian Moreno <amorenoz@redhat.com>
> Sent: Monday, July 6, 2020 7:25 PM
> To: dev@dpdk.org; Xia, Chenbo <chenbo.xia@intel.com>; Ye, Xiaolong
> <xiaolong.ye@intel.com>; shahafs@mellanox.com; matan@mellanox.com;
> maxime.coquelin@redhat.com; Wang, Xiao W <xiao.w.wang@intel.com>;
> viacheslavo@mellanox.com
> Cc: jasowang@redhat.com; lulu@redhat.com; Adrian Moreno
> <amorenoz@redhat.com>
> Subject: [PATCH v3 6/8] vhost: add support for virtio get status message
> 
> This patch adds support to the new Virtio device get status Vhost-user message.
> 
> The driver can send this new message to read the device status.
> 
> One of the uses of this message is to ensure the feature negotiation has
> succeded.  According to the virtio spec, after completing the feature negotiation,
> the driver sets the FEATURE_OK status bit and re-reads it to ensure the device
> has accepted the features.
> 
> This patch also clears the FEATURE_OK status bit if the feature negotiation has
> failed to let the driver know about his failure.
> 
> Signed-off-by: Adrian Moreno <amorenoz@redhat.com>
> ---
>  lib/librte_vhost/vhost.h      |  2 ++
>  lib/librte_vhost/vhost_user.c | 32 ++++++++++++++++++++++++++++++++
> lib/librte_vhost/vhost_user.h |  1 +
>  3 files changed, 35 insertions(+)
> 
> diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h index
> 25d31c71b..e743821cc 100644
> --- a/lib/librte_vhost/vhost.h
> +++ b/lib/librte_vhost/vhost.h
> @@ -32,6 +32,8 @@
>  #define VIRTIO_DEV_BUILTIN_VIRTIO_NET 4
>  /* Used to indicate that the device has its own data path and configured */
> #define VIRTIO_DEV_VDPA_CONFIGURED 8
> +/* Used to indicate that the feature negotiation failed */ #define
> +VIRTIO_DEV_FEATURES_FAILED 16
> 
>  /* Backend value set by guest. */
>  #define VIRTIO_DEV_STOPPED -1
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c index
> 8d3d13913..5b6f4fb62 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -88,6 +88,7 @@ static const char *vhost_message_str[VHOST_USER_MAX]
> = {
>  	[VHOST_USER_GET_INFLIGHT_FD] = "VHOST_USER_GET_INFLIGHT_FD",
>  	[VHOST_USER_SET_INFLIGHT_FD] = "VHOST_USER_SET_INFLIGHT_FD",
>  	[VHOST_USER_SET_STATUS] = "VHOST_USER_SET_STATUS",
> +	[VHOST_USER_GET_STATUS] = "VHOST_USER_GET_STATUS",
>  };
> 
>  static int send_vhost_reply(int sockfd, struct VhostUserMsg *msg); @@ -339,6
> +340,9 @@ vhost_user_set_features(struct virtio_net **pdev, struct
> VhostUserMsg *msg,
>  		VHOST_LOG_CONFIG(ERR,
>  			"(%d) received invalid negotiated features.\n",
>  			dev->vid);
> +		dev->flags |= VIRTIO_DEV_FEATURES_FAILED;
> +		dev->status &= ~VIRTIO_DEVICE_STATUS_FEATURES_OK;
> +
>  		return RTE_VHOST_MSG_RESULT_ERR;
>  	}
> 
> @@ -402,6 +406,7 @@ vhost_user_set_features(struct virtio_net **pdev, struct
> VhostUserMsg *msg,
>  	if (vdpa_dev)
>  		vdpa_dev->ops->set_features(dev->vid);
> 
> +	dev->flags &= ~VIRTIO_DEV_FEATURES_FAILED;
>  	return RTE_VHOST_MSG_RESULT_OK;
>  }
> 
> @@ -2458,6 +2463,22 @@ vhost_user_postcopy_end(struct virtio_net **pdev,
> struct VhostUserMsg *msg,
>  	return RTE_VHOST_MSG_RESULT_REPLY;
>  }
> 
> +static int
> +vhost_user_get_status(struct virtio_net **pdev, struct VhostUserMsg *msg,
> +		      int main_fd __rte_unused)
> +{
> +	struct virtio_net *dev = *pdev;
> +
> +	if (validate_msg_fds(msg, 0) != 0)
> +		return RTE_VHOST_MSG_RESULT_ERR;
> +
> +	msg->payload.u64 = dev->status;
> +	msg->size = sizeof(msg->payload.u64);
> +	msg->fd_num = 0;
> +
> +	return RTE_VHOST_MSG_RESULT_REPLY;
> +}
> +
>  static int
>  vhost_user_set_status(struct virtio_net **pdev, struct VhostUserMsg *msg,
>  			int main_fd __rte_unused)
> @@ -2476,6 +2497,16 @@ vhost_user_set_status(struct virtio_net **pdev,
> struct VhostUserMsg *msg,
> 
>  	dev->status = msg->payload.u64;
> 
> +	if ((dev->status & VIRTIO_DEVICE_STATUS_FEATURES_OK) &&
> +	    (dev->flags & VIRTIO_DEV_FEATURES_FAILED)) {
> +		VHOST_LOG_CONFIG(ERR, "FEATURES_OK bit is set but feature
> negotiation failed\n");
> +		/*
> +		 * Clear the bit to let the driver know about the feature
> +		 * negotiation failure
> +		 */
> +		dev->status &= ~VIRTIO_DEVICE_STATUS_FEATURES_OK;
> +	}
> +
>  	VHOST_LOG_CONFIG(INFO, "New device status(0x%08x):\n"
>  			"\t-ACKNOWLEDGE: %u\n"
>  			"\t-DRIVER: %u\n"
> @@ -2527,6 +2558,7 @@ static vhost_message_handler_t
> vhost_message_handlers[VHOST_USER_MAX] = {
>  	[VHOST_USER_GET_INFLIGHT_FD] = vhost_user_get_inflight_fd,
>  	[VHOST_USER_SET_INFLIGHT_FD] = vhost_user_set_inflight_fd,
>  	[VHOST_USER_SET_STATUS] = vhost_user_set_status,
> +	[VHOST_USER_GET_STATUS] = vhost_user_get_status,
>  };
> 
>  /* return bytes# of read on success or negative val on failure. */ diff --git
> a/lib/librte_vhost/vhost_user.h b/lib/librte_vhost/vhost_user.h index
> 82885ab5e..16fe03f88 100644
> --- a/lib/librte_vhost/vhost_user.h
> +++ b/lib/librte_vhost/vhost_user.h
> @@ -58,6 +58,7 @@ typedef enum VhostUserRequest {
>  	VHOST_USER_GET_INFLIGHT_FD = 31,
>  	VHOST_USER_SET_INFLIGHT_FD = 32,
>  	VHOST_USER_SET_STATUS = 39,
> +	VHOST_USER_GET_STATUS = 40,
>  	VHOST_USER_MAX = 41
>  } VhostUserRequest;
> 
> --
> 2.26.2

Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>