[dpdk-dev,v4,3/5] vhost: add apis for datapath configuration

Message ID 20180310100148.12030-4-zhihong.wang@intel.com (mailing list archive)
State Superseded, archived
Headers

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/Intel-compilation fail Compilation issues

Commit Message

Zhihong Wang March 10, 2018, 10:01 a.m. UTC
  This patch adds APIs for datapath configuration.

The did of the vhost-user socket can be set to identify the backend device,
in this case each vhost-user socket can have only 1 connection. The did is
set to -1 by default when the software datapath is used.

Signed-off-by: Zhihong Wang <zhihong.wang@intel.com>
---
Changes in v4:

 1. Remove the "engine" concept in the lib.

 lib/librte_vhost/rte_vhost.h           | 35 +++++++++++++++++++++++++++++++++
 lib/librte_vhost/rte_vhost_version.map |  3 +++
 lib/librte_vhost/socket.c              | 36 ++++++++++++++++++++++++++++++++++
 lib/librte_vhost/vhost.c               | 25 +++++++++++++++++++++++
 lib/librte_vhost/vhost.h               |  9 +++++++++
 5 files changed, 108 insertions(+)
  

Comments

Maxime Coquelin March 31, 2018, 7:04 a.m. UTC | #1
On 03/10/2018 11:01 AM, Zhihong Wang wrote:
> This patch adds APIs for datapath configuration.
> 
> The did of the vhost-user socket can be set to identify the backend device,
> in this case each vhost-user socket can have only 1 connection. The did is
> set to -1 by default when the software datapath is used.
> 
> Signed-off-by: Zhihong Wang <zhihong.wang@intel.com>
> ---
> Changes in v4:
> 
>   1. Remove the "engine" concept in the lib.
> 
>   lib/librte_vhost/rte_vhost.h           | 35 +++++++++++++++++++++++++++++++++
>   lib/librte_vhost/rte_vhost_version.map |  3 +++
>   lib/librte_vhost/socket.c              | 36 ++++++++++++++++++++++++++++++++++
>   lib/librte_vhost/vhost.c               | 25 +++++++++++++++++++++++
>   lib/librte_vhost/vhost.h               |  9 +++++++++
>   5 files changed, 108 insertions(+)
> 
> diff --git a/lib/librte_vhost/rte_vhost.h b/lib/librte_vhost/rte_vhost.h
> index 671ea5053..d50f4c67d 100644
> --- a/lib/librte_vhost/rte_vhost.h
> +++ b/lib/librte_vhost/rte_vhost.h
> @@ -200,6 +200,30 @@ int rte_vhost_driver_register(const char *path, uint64_t flags);
>   int rte_vhost_driver_unregister(const char *path);
>   
>   /**
> + * Set the device id, enforce single connection per socket
> + *
> + * @param path
> + *  The vhost-user socket file path
> + * @param did
> + *  Device id
> + * @return
> + *  0 on success, -1 on failure
> + */
> +int __rte_experimental
> +rte_vhost_driver_set_vdpa_did(const char *path, int did);

IIUC, we call this to attach a VDPA device to a Vhost-user port?

What about having this named explicitly? Something like:

rte_vhost_driver_attach_vdpa_did(const char *path, int did)
rte_vhost_driver_detach_vdpa_did(const char *path)

The later would set to did -1

This is not mandatory though

> +
> +/**
> + * Get the device id
> + *
> + * @param path
> + *  The vhost-user socket file path
> + * @return
> + *  Device id, -1 on failure
> + */
> +int __rte_experimental
> +rte_vhost_driver_get_vdpa_did(const char *path);
> +
> +/**
>    * Set the feature bits the vhost-user driver supports.
>    *
>    * @param path
> @@ -464,6 +488,17 @@ int rte_vhost_vring_call(int vid, uint16_t vring_idx);
>    */
>   uint32_t rte_vhost_rx_queue_count(int vid, uint16_t qid);
>   
> +/**
> + * Get vdpa device id for vhost device.
> + *
> + * @param vid
> + *  vhost device ID
> + * @return
> + *  device id
> + */
> +int __rte_experimental
> +rte_vhost_get_vdpa_did(int vid);
> +
>   #ifdef __cplusplus
>   }
>   #endif
> diff --git a/lib/librte_vhost/rte_vhost_version.map b/lib/librte_vhost/rte_vhost_version.map
> index 7bcffb490..6e2d5364a 100644
> --- a/lib/librte_vhost/rte_vhost_version.map
> +++ b/lib/librte_vhost/rte_vhost_version.map
> @@ -64,4 +64,7 @@ EXPERIMENTAL {
>   	rte_vdpa_register_device;
>   	rte_vdpa_unregister_device;
>   	rte_vdpa_find_device_id;
> +	rte_vhost_driver_set_vdpa_did;
> +	rte_vhost_driver_get_vdpa_did;
> +	rte_vhost_get_vdpa_did;
>   } DPDK_18.02;
> diff --git a/lib/librte_vhost/socket.c b/lib/librte_vhost/socket.c
> index cfc31e179..3d58da94e 100644
> --- a/lib/librte_vhost/socket.c
> +++ b/lib/librte_vhost/socket.c
> @@ -52,6 +52,13 @@ struct vhost_user_socket {
>   	uint64_t supported_features;
>   	uint64_t features;
>   
> +	/*
> +	 * Device id to identify a specific backend device.
> +	 * It's set to -1 for the default software implementation.
> +	 * If valid, one socket can have 1 connection only.
> +	 */
> +	int did;
I would rename it to something like vdpa_did or even better,
vdpa_dev_id. At least prefix it with vdpa not to confuse the user.

> +
>   	struct vhost_device_ops const *notify_ops;
>   };
>   
> @@ -545,6 +552,35 @@ find_vhost_user_socket(const char *path)
>   }
>   
>   int
> +rte_vhost_driver_set_vdpa_did(const char *path, int did)
> +{
> +	struct vhost_user_socket *vsocket;
> +
> +	pthread_mutex_lock(&vhost_user.mutex);
> +	vsocket = find_vhost_user_socket(path);
> +	if (vsocket)
> +		vsocket->did = did;

I guess it is possible to know whether the did exists
at that time. Maybe we could check this?

> +	pthread_mutex_unlock(&vhost_user.mutex);
> +
> +	return vsocket ? 0 : -1;
> +}
> +
> +int
> +rte_vhost_driver_get_vdpa_did(const char *path)
> +{
> +	struct vhost_user_socket *vsocket;
> +	int did = -1;
> +
> +	pthread_mutex_lock(&vhost_user.mutex);
> +	vsocket = find_vhost_user_socket(path);
> +	if (vsocket)
> +		did = vsocket->did;
> +	pthread_mutex_unlock(&vhost_user.mutex);
> +
> +	return did;
> +}
> +
> +int
>   rte_vhost_driver_disable_features(const char *path, uint64_t features)
>   {
>   	struct vhost_user_socket *vsocket;
> diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
> index f6f12a03b..1740cc1ab 100644
> --- a/lib/librte_vhost/vhost.c
> +++ b/lib/librte_vhost/vhost.c
> @@ -283,6 +283,7 @@ vhost_new_device(void)
>   	dev->vid = i;
>   	dev->flags = VIRTIO_DEV_BUILTIN_VIRTIO_NET;
>   	dev->slave_req_fd = -1;
> +	dev->did = -1;
>   
>   	return i;
>   }
> @@ -311,6 +312,20 @@ vhost_destroy_device(int vid)
>   }
>   
>   void
> +vhost_set_vdpa_did(int vid, int did)
> +{
> +	struct virtio_net *dev = get_device(vid);
> +
> +	if (did < 0)
> +		return;
> +
> +	if (dev == NULL)
> +		return;
> +
> +	dev->did = did;
> +}
> +
> +void
>   vhost_set_ifname(int vid, const char *if_name, unsigned int if_len)
>   {
>   	struct virtio_net *dev;
> @@ -614,3 +629,13 @@ rte_vhost_rx_queue_count(int vid, uint16_t qid)
>   
>   	return *((volatile uint16_t *)&vq->avail->idx) - vq->last_avail_idx;
>   }
> +
> +int rte_vhost_get_vdpa_did(int vid)
> +{
> +	struct virtio_net *dev = get_device(vid);
> +
> +	if (dev == NULL)
> +		return -1;
> +
> +	return dev->did;
> +}
> diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
> index 2e28e4026..2970c1eab 100644
> --- a/lib/librte_vhost/vhost.h
> +++ b/lib/librte_vhost/vhost.h
> @@ -19,6 +19,7 @@
>   #include <rte_rwlock.h>
>   
>   #include "rte_vhost.h"
> +#include "rte_vdpa.h"
>   
>   /* Used to indicate that the device is running on a data core */
>   #define VIRTIO_DEV_RUNNING 1
> @@ -239,6 +240,12 @@ struct virtio_net {
>   	struct guest_page       *guest_pages;
>   
>   	int			slave_req_fd;
> +
> +	/*
> +	 * Device id to identify a specific backend device.
> +	 * It's set to -1 for the default software implementation.
> +	 */
> +	int			did;

Same as for struct vhost_user_socket, it would be less confusing to
prefix it with vdpa.

>   } __rte_cache_aligned;
>   
>   
> @@ -365,6 +372,8 @@ void free_vq(struct vhost_virtqueue *vq);
>   
>   int alloc_vring_queue(struct virtio_net *dev, uint32_t vring_idx);
>   
> +void vhost_set_vdpa_did(int vid, int did);
> +
>   void vhost_set_ifname(int, const char *if_name, unsigned int if_len);
>   void vhost_enable_dequeue_zero_copy(int vid);
>   void vhost_set_builtin_virtio_net(int vid, bool enable);
>
  
Zhihong Wang April 2, 2018, 2:01 a.m. UTC | #2
> -----Original Message-----

> From: Maxime Coquelin [mailto:maxime.coquelin@redhat.com]

> Sent: Saturday, March 31, 2018 3:04 PM

> To: Wang, Zhihong <zhihong.wang@intel.com>; dev@dpdk.org

> Cc: Tan, Jianfeng <jianfeng.tan@intel.com>; Bie, Tiwei

> <tiwei.bie@intel.com>; yliu@fridaylinux.org; Liang, Cunming

> <cunming.liang@intel.com>; Wang, Xiao W <xiao.w.wang@intel.com>; Daly,

> Dan <dan.daly@intel.com>

> Subject: Re: [PATCH v4 3/5] vhost: add apis for datapath configuration

> 

> 

> 

> On 03/10/2018 11:01 AM, Zhihong Wang wrote:

> > This patch adds APIs for datapath configuration.

> >

> > The did of the vhost-user socket can be set to identify the backend device,

> > in this case each vhost-user socket can have only 1 connection. The did is

> > set to -1 by default when the software datapath is used.

> >

> > Signed-off-by: Zhihong Wang <zhihong.wang@intel.com>

> > ---

> > Changes in v4:

> >

> >   1. Remove the "engine" concept in the lib.

> >

> >   lib/librte_vhost/rte_vhost.h           | 35

> +++++++++++++++++++++++++++++++++

> >   lib/librte_vhost/rte_vhost_version.map |  3 +++

> >   lib/librte_vhost/socket.c              | 36

> ++++++++++++++++++++++++++++++++++

> >   lib/librte_vhost/vhost.c               | 25 +++++++++++++++++++++++

> >   lib/librte_vhost/vhost.h               |  9 +++++++++

> >   5 files changed, 108 insertions(+)

> >

> > diff --git a/lib/librte_vhost/rte_vhost.h b/lib/librte_vhost/rte_vhost.h

> > index 671ea5053..d50f4c67d 100644

> > --- a/lib/librte_vhost/rte_vhost.h

> > +++ b/lib/librte_vhost/rte_vhost.h

> > @@ -200,6 +200,30 @@ int rte_vhost_driver_register(const char *path,

> uint64_t flags);

> >   int rte_vhost_driver_unregister(const char *path);

> >

> >   /**

> > + * Set the device id, enforce single connection per socket

> > + *

> > + * @param path

> > + *  The vhost-user socket file path

> > + * @param did

> > + *  Device id

> > + * @return

> > + *  0 on success, -1 on failure

> > + */

> > +int __rte_experimental

> > +rte_vhost_driver_set_vdpa_did(const char *path, int did);

> 

> IIUC, we call this to attach a VDPA device to a Vhost-user port?

> 

> What about having this named explicitly? Something like:

> 

> rte_vhost_driver_attach_vdpa_did(const char *path, int did)

> rte_vhost_driver_detach_vdpa_did(const char *path)

> 

> The later would set to did -1


Great. This does make things clearer.

> 

> This is not mandatory though

> 

> > +

> > +/**

> > + * Get the device id

> > + *

> > + * @param path

> > + *  The vhost-user socket file path

> > + * @return

> > + *  Device id, -1 on failure

> > + */

> > +int __rte_experimental

> > +rte_vhost_driver_get_vdpa_did(const char *path);

> > +

> > +/**

> >    * Set the feature bits the vhost-user driver supports.

> >    *

> >    * @param path

> > @@ -464,6 +488,17 @@ int rte_vhost_vring_call(int vid, uint16_t vring_idx);

> >    */

> >   uint32_t rte_vhost_rx_queue_count(int vid, uint16_t qid);

> >

> > +/**

> > + * Get vdpa device id for vhost device.

> > + *

> > + * @param vid

> > + *  vhost device ID

> > + * @return

> > + *  device id

> > + */

> > +int __rte_experimental

> > +rte_vhost_get_vdpa_did(int vid);

> > +

> >   #ifdef __cplusplus

> >   }

> >   #endif

> > diff --git a/lib/librte_vhost/rte_vhost_version.map

> b/lib/librte_vhost/rte_vhost_version.map

> > index 7bcffb490..6e2d5364a 100644

> > --- a/lib/librte_vhost/rte_vhost_version.map

> > +++ b/lib/librte_vhost/rte_vhost_version.map

> > @@ -64,4 +64,7 @@ EXPERIMENTAL {

> >   	rte_vdpa_register_device;

> >   	rte_vdpa_unregister_device;

> >   	rte_vdpa_find_device_id;

> > +	rte_vhost_driver_set_vdpa_did;

> > +	rte_vhost_driver_get_vdpa_did;

> > +	rte_vhost_get_vdpa_did;

> >   } DPDK_18.02;

> > diff --git a/lib/librte_vhost/socket.c b/lib/librte_vhost/socket.c

> > index cfc31e179..3d58da94e 100644

> > --- a/lib/librte_vhost/socket.c

> > +++ b/lib/librte_vhost/socket.c

> > @@ -52,6 +52,13 @@ struct vhost_user_socket {

> >   	uint64_t supported_features;

> >   	uint64_t features;

> >

> > +	/*

> > +	 * Device id to identify a specific backend device.

> > +	 * It's set to -1 for the default software implementation.

> > +	 * If valid, one socket can have 1 connection only.

> > +	 */

> > +	int did;

> I would rename it to something like vdpa_did or even better,

> vdpa_dev_id. At least prefix it with vdpa not to confuse the user.


Good suggestion.

> 

> > +

> >   	struct vhost_device_ops const *notify_ops;

> >   };

> >

> > @@ -545,6 +552,35 @@ find_vhost_user_socket(const char *path)

> >   }

> >

> >   int

> > +rte_vhost_driver_set_vdpa_did(const char *path, int did)

> > +{

> > +	struct vhost_user_socket *vsocket;

> > +

> > +	pthread_mutex_lock(&vhost_user.mutex);

> > +	vsocket = find_vhost_user_socket(path);

> > +	if (vsocket)

> > +		vsocket->did = did;

> 

> I guess it is possible to know whether the did exists

> at that time. Maybe we could check this?


Ok.

> 

> > +	pthread_mutex_unlock(&vhost_user.mutex);

> > +

> > +	return vsocket ? 0 : -1;

> > +}

> > +

> > +int

> > +rte_vhost_driver_get_vdpa_did(const char *path)

> > +{

> > +	struct vhost_user_socket *vsocket;

> > +	int did = -1;

> > +

> > +	pthread_mutex_lock(&vhost_user.mutex);

> > +	vsocket = find_vhost_user_socket(path);

> > +	if (vsocket)

> > +		did = vsocket->did;

> > +	pthread_mutex_unlock(&vhost_user.mutex);

> > +

> > +	return did;

> > +}

> > +

> > +int

> >   rte_vhost_driver_disable_features(const char *path, uint64_t features)

> >   {

> >   	struct vhost_user_socket *vsocket;

> > diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c

> > index f6f12a03b..1740cc1ab 100644

> > --- a/lib/librte_vhost/vhost.c

> > +++ b/lib/librte_vhost/vhost.c

> > @@ -283,6 +283,7 @@ vhost_new_device(void)

> >   	dev->vid = i;

> >   	dev->flags = VIRTIO_DEV_BUILTIN_VIRTIO_NET;

> >   	dev->slave_req_fd = -1;

> > +	dev->did = -1;

> >

> >   	return i;

> >   }

> > @@ -311,6 +312,20 @@ vhost_destroy_device(int vid)

> >   }

> >

> >   void

> > +vhost_set_vdpa_did(int vid, int did)

> > +{

> > +	struct virtio_net *dev = get_device(vid);

> > +

> > +	if (did < 0)

> > +		return;

> > +

> > +	if (dev == NULL)

> > +		return;

> > +

> > +	dev->did = did;

> > +}

> > +

> > +void

> >   vhost_set_ifname(int vid, const char *if_name, unsigned int if_len)

> >   {

> >   	struct virtio_net *dev;

> > @@ -614,3 +629,13 @@ rte_vhost_rx_queue_count(int vid, uint16_t qid)

> >

> >   	return *((volatile uint16_t *)&vq->avail->idx) - vq->last_avail_idx;

> >   }

> > +

> > +int rte_vhost_get_vdpa_did(int vid)

> > +{

> > +	struct virtio_net *dev = get_device(vid);

> > +

> > +	if (dev == NULL)

> > +		return -1;

> > +

> > +	return dev->did;

> > +}

> > diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h

> > index 2e28e4026..2970c1eab 100644

> > --- a/lib/librte_vhost/vhost.h

> > +++ b/lib/librte_vhost/vhost.h

> > @@ -19,6 +19,7 @@

> >   #include <rte_rwlock.h>

> >

> >   #include "rte_vhost.h"

> > +#include "rte_vdpa.h"

> >

> >   /* Used to indicate that the device is running on a data core */

> >   #define VIRTIO_DEV_RUNNING 1

> > @@ -239,6 +240,12 @@ struct virtio_net {

> >   	struct guest_page       *guest_pages;

> >

> >   	int			slave_req_fd;

> > +

> > +	/*

> > +	 * Device id to identify a specific backend device.

> > +	 * It's set to -1 for the default software implementation.

> > +	 */

> > +	int			did;

> 

> Same as for struct vhost_user_socket, it would be less confusing to

> prefix it with vdpa.


Ok.

Thanks
-Zhihong

> 

> >   } __rte_cache_aligned;

> >

> >

> > @@ -365,6 +372,8 @@ void free_vq(struct vhost_virtqueue *vq);

> >

> >   int alloc_vring_queue(struct virtio_net *dev, uint32_t vring_idx);

> >

> > +void vhost_set_vdpa_did(int vid, int did);

> > +

> >   void vhost_set_ifname(int, const char *if_name, unsigned int if_len);

> >   void vhost_enable_dequeue_zero_copy(int vid);

> >   void vhost_set_builtin_virtio_net(int vid, bool enable);

> >
  

Patch

diff --git a/lib/librte_vhost/rte_vhost.h b/lib/librte_vhost/rte_vhost.h
index 671ea5053..d50f4c67d 100644
--- a/lib/librte_vhost/rte_vhost.h
+++ b/lib/librte_vhost/rte_vhost.h
@@ -200,6 +200,30 @@  int rte_vhost_driver_register(const char *path, uint64_t flags);
 int rte_vhost_driver_unregister(const char *path);
 
 /**
+ * Set the device id, enforce single connection per socket
+ *
+ * @param path
+ *  The vhost-user socket file path
+ * @param did
+ *  Device id
+ * @return
+ *  0 on success, -1 on failure
+ */
+int __rte_experimental
+rte_vhost_driver_set_vdpa_did(const char *path, int did);
+
+/**
+ * Get the device id
+ *
+ * @param path
+ *  The vhost-user socket file path
+ * @return
+ *  Device id, -1 on failure
+ */
+int __rte_experimental
+rte_vhost_driver_get_vdpa_did(const char *path);
+
+/**
  * Set the feature bits the vhost-user driver supports.
  *
  * @param path
@@ -464,6 +488,17 @@  int rte_vhost_vring_call(int vid, uint16_t vring_idx);
  */
 uint32_t rte_vhost_rx_queue_count(int vid, uint16_t qid);
 
+/**
+ * Get vdpa device id for vhost device.
+ *
+ * @param vid
+ *  vhost device ID
+ * @return
+ *  device id
+ */
+int __rte_experimental
+rte_vhost_get_vdpa_did(int vid);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/lib/librte_vhost/rte_vhost_version.map b/lib/librte_vhost/rte_vhost_version.map
index 7bcffb490..6e2d5364a 100644
--- a/lib/librte_vhost/rte_vhost_version.map
+++ b/lib/librte_vhost/rte_vhost_version.map
@@ -64,4 +64,7 @@  EXPERIMENTAL {
 	rte_vdpa_register_device;
 	rte_vdpa_unregister_device;
 	rte_vdpa_find_device_id;
+	rte_vhost_driver_set_vdpa_did;
+	rte_vhost_driver_get_vdpa_did;
+	rte_vhost_get_vdpa_did;
 } DPDK_18.02;
diff --git a/lib/librte_vhost/socket.c b/lib/librte_vhost/socket.c
index cfc31e179..3d58da94e 100644
--- a/lib/librte_vhost/socket.c
+++ b/lib/librte_vhost/socket.c
@@ -52,6 +52,13 @@  struct vhost_user_socket {
 	uint64_t supported_features;
 	uint64_t features;
 
+	/*
+	 * Device id to identify a specific backend device.
+	 * It's set to -1 for the default software implementation.
+	 * If valid, one socket can have 1 connection only.
+	 */
+	int did;
+
 	struct vhost_device_ops const *notify_ops;
 };
 
@@ -545,6 +552,35 @@  find_vhost_user_socket(const char *path)
 }
 
 int
+rte_vhost_driver_set_vdpa_did(const char *path, int did)
+{
+	struct vhost_user_socket *vsocket;
+
+	pthread_mutex_lock(&vhost_user.mutex);
+	vsocket = find_vhost_user_socket(path);
+	if (vsocket)
+		vsocket->did = did;
+	pthread_mutex_unlock(&vhost_user.mutex);
+
+	return vsocket ? 0 : -1;
+}
+
+int
+rte_vhost_driver_get_vdpa_did(const char *path)
+{
+	struct vhost_user_socket *vsocket;
+	int did = -1;
+
+	pthread_mutex_lock(&vhost_user.mutex);
+	vsocket = find_vhost_user_socket(path);
+	if (vsocket)
+		did = vsocket->did;
+	pthread_mutex_unlock(&vhost_user.mutex);
+
+	return did;
+}
+
+int
 rte_vhost_driver_disable_features(const char *path, uint64_t features)
 {
 	struct vhost_user_socket *vsocket;
diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
index f6f12a03b..1740cc1ab 100644
--- a/lib/librte_vhost/vhost.c
+++ b/lib/librte_vhost/vhost.c
@@ -283,6 +283,7 @@  vhost_new_device(void)
 	dev->vid = i;
 	dev->flags = VIRTIO_DEV_BUILTIN_VIRTIO_NET;
 	dev->slave_req_fd = -1;
+	dev->did = -1;
 
 	return i;
 }
@@ -311,6 +312,20 @@  vhost_destroy_device(int vid)
 }
 
 void
+vhost_set_vdpa_did(int vid, int did)
+{
+	struct virtio_net *dev = get_device(vid);
+
+	if (did < 0)
+		return;
+
+	if (dev == NULL)
+		return;
+
+	dev->did = did;
+}
+
+void
 vhost_set_ifname(int vid, const char *if_name, unsigned int if_len)
 {
 	struct virtio_net *dev;
@@ -614,3 +629,13 @@  rte_vhost_rx_queue_count(int vid, uint16_t qid)
 
 	return *((volatile uint16_t *)&vq->avail->idx) - vq->last_avail_idx;
 }
+
+int rte_vhost_get_vdpa_did(int vid)
+{
+	struct virtio_net *dev = get_device(vid);
+
+	if (dev == NULL)
+		return -1;
+
+	return dev->did;
+}
diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
index 2e28e4026..2970c1eab 100644
--- a/lib/librte_vhost/vhost.h
+++ b/lib/librte_vhost/vhost.h
@@ -19,6 +19,7 @@ 
 #include <rte_rwlock.h>
 
 #include "rte_vhost.h"
+#include "rte_vdpa.h"
 
 /* Used to indicate that the device is running on a data core */
 #define VIRTIO_DEV_RUNNING 1
@@ -239,6 +240,12 @@  struct virtio_net {
 	struct guest_page       *guest_pages;
 
 	int			slave_req_fd;
+
+	/*
+	 * Device id to identify a specific backend device.
+	 * It's set to -1 for the default software implementation.
+	 */
+	int			did;
 } __rte_cache_aligned;
 
 
@@ -365,6 +372,8 @@  void free_vq(struct vhost_virtqueue *vq);
 
 int alloc_vring_queue(struct virtio_net *dev, uint32_t vring_idx);
 
+void vhost_set_vdpa_did(int vid, int did);
+
 void vhost_set_ifname(int, const char *if_name, unsigned int if_len);
 void vhost_enable_dequeue_zero_copy(int vid);
 void vhost_set_builtin_virtio_net(int vid, bool enable);