[dpdk-dev] [PATCH 3/3] vhost: support VFIO based accelerator

Maxime Coquelin maxime.coquelin at redhat.com
Tue Mar 6 15:24:27 CET 2018



On 03/06/2018 11:43 AM, Tiwei Bie wrote:
> This commit adds the VFIO based accelerator support to
> vhost. A new API is provided to support asking QEMU to
> do further setup to allow notifications and interrupts
> being delivered directly between the driver in guest
> and the vDPA device in host.
> 
> Signed-off-by: Tiwei Bie <tiwei.bie at intel.com>
> ---
>   lib/librte_vhost/rte_vhost.h           |  28 ++++++
>   lib/librte_vhost/rte_vhost_version.map |   1 +
>   lib/librte_vhost/vhost_user.c          | 166 +++++++++++++++++++++++++++++++++
>   lib/librte_vhost/vhost_user.h          |   9 ++
>   4 files changed, 204 insertions(+)
> 
> diff --git a/lib/librte_vhost/rte_vhost.h b/lib/librte_vhost/rte_vhost.h
> index d5589c543..68842e908 100644
> --- a/lib/librte_vhost/rte_vhost.h
> +++ b/lib/librte_vhost/rte_vhost.h
> @@ -35,6 +35,7 @@ extern "C" {
>   #define RTE_VHOST_USER_PROTOCOL_F_REPLY_ACK	3
>   #define RTE_VHOST_USER_PROTOCOL_F_NET_MTU	4
>   #define RTE_VHOST_USER_PROTOCOL_F_SLAVE_REQ	5
> +#define RTE_VHOST_USER_PROTOCOL_F_VFIO		8
>   #define RTE_VHOST_USER_F_PROTOCOL_FEATURES	30
>   
>   /**
> @@ -591,6 +592,33 @@ rte_vhost_get_vdpa_eid(int vid);
>   int __rte_experimental
>   rte_vhost_get_vdpa_did(int vid);
>   
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this API may change without prior notice
> + *
> + * Enable or disable the VFIO based accelerator for vhost-user.
> + *
> + * This function is to ask QEMU to do further setup to better
> + * support the vDPA device at vhost user backend. With this
> + * setup, the notifications and interrupts will be delivered
> + * directly between the driver in guest and the vDPA device
> + * in host if platform supports e.g. EPT and Posted interrupt.
> + * It's nice to have, and not mandatory.
> + *
> + * @param vid
> + *  vhost device ID
> + * @param int
> + *  Enable or disable
> + *
> + * @return
> + *   0: success
> + *   -ENODEV: no such vhost device
> + *   -ENOTSUP: device does not support VFIO based accelerator feature
> + *   -EINVAL: there is no accelerator assigned to this vhost device
> + *   -EFAULT: failed to talk with QEMU
> + */
> +int rte_vhost_vfio_accelerator_ctrl(int vid, int enable);
> +
>   #ifdef __cplusplus
>   }
>   #endif
> diff --git a/lib/librte_vhost/rte_vhost_version.map b/lib/librte_vhost/rte_vhost_version.map
> index 36257e51b..ca970170f 100644
> --- a/lib/librte_vhost/rte_vhost_version.map
> +++ b/lib/librte_vhost/rte_vhost_version.map
> @@ -72,6 +72,7 @@ EXPERIMENTAL {
>   	rte_vhost_set_vring_base;
>   	rte_vhost_get_vdpa_eid;
>   	rte_vhost_get_vdpa_did;
> +	rte_vhost_vfio_accelerator_ctrl;
>   	rte_vdpa_register_engine;
>   	rte_vdpa_unregister_engine;
>   	rte_vdpa_find_engine_id;
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index e3a1dfbfb..a65598d80 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -35,6 +35,7 @@
>   #include <rte_common.h>
>   #include <rte_malloc.h>
>   #include <rte_log.h>
> +#include <rte_vhost.h>
>   
>   #include "iotlb.h"
>   #include "vhost.h"
> @@ -1628,6 +1629,27 @@ vhost_user_msg_handler(int vid, int fd)
>   	return 0;
>   }
>   
> +static int process_slave_message_reply(struct virtio_net *dev,
> +				       const VhostUserMsg *msg)
> +{
> +	VhostUserMsg msg_reply;
> +
> +	if ((msg->flags & VHOST_USER_NEED_REPLY) == 0)
> +		return 0;
> +
> +	if (read_vhost_message(dev->slave_req_fd, &msg_reply) < 0)
> +		return -1;
> +
> +	if (msg_reply.request.slave != msg->request.slave) {
> +		RTE_LOG(ERR, VHOST_CONFIG,
> +			"received unexpected msg type (%u), expected %u\n",
> +			msg_reply.request.slave, msg->request.slave);
> +		return -1;
> +	}
> +
> +	return msg_reply.payload.u64;
> +}
> +
>   int
>   vhost_user_iotlb_miss(struct virtio_net *dev, uint64_t iova, uint8_t perm)
>   {
> @@ -1653,3 +1675,147 @@ vhost_user_iotlb_miss(struct virtio_net *dev, uint64_t iova, uint8_t perm)
>   
>   	return 0;
>   }
> +
> +static int vhost_user_slave_set_vring_file(struct virtio_net *dev,
> +					   uint32_t request,
> +					   struct vhost_vring_file *file)
Why passing the request as an argument?
It seems to be called only with the same request ID.

> +{
> +	int *fdp = NULL;
> +	size_t fd_num = 0;
> +	int ret;
> +	struct VhostUserMsg msg = {
> +		.request.slave = request,
> +		.flags = VHOST_USER_VERSION | VHOST_USER_NEED_REPLY,
> +		.payload.u64 = file->index & VHOST_USER_VRING_IDX_MASK,
> +		.size = sizeof(msg.payload.u64),
> +	};
> +
> +	if (file->fd < 0)
> +		msg.payload.u64 |= VHOST_USER_VRING_NOFD_MASK;
> +	else {
> +		fdp = &file->fd;
> +		fd_num = 1;
> +	}
> +
> +	ret = send_vhost_message(dev->slave_req_fd, &msg, fdp, fd_num);
> +	if (ret < 0) {
> +		RTE_LOG(ERR, VHOST_CONFIG,
> +			"Failed to send slave message %u (%d)\n",
> +			request, ret);
> +		return ret;
> +	}
> +
> +	return process_slave_message_reply(dev, &msg);

Maybe not needed right now, but we'll need a lock to avoid concurrent
requests sending and waiting for reply.

Thanks,
Maxime


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