[01/28] vhost: introduce vhost transport operations structure

Message ID 1560957293-17294-2-git-send-email-ndragazis@arrikto.com
State New
Delegated to: Maxime Coquelin
Headers show
Series
  • vhost: add virtio-vhost-user transport
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Checks

Context Check Description
ci/Intel-compilation fail Compilation issues
ci/intel-Performance-Testing success Performance Testing PASS
ci/mellanox-Performance-Testing success Performance Testing PASS
ci/checkpatch success coding style OK

Commit Message

Nikos Dragazis June 19, 2019, 3:14 p.m.
This is the first of a series of patches, whose purpose is to add
support for the virtio-vhost-user transport. This is a vhost-user
transport implementation that is different from the default AF_UNIX
transport. It uses the virtio-vhost-user PCI device in order to tunnel
vhost-user protocol messages over virtio. This lets guests act as vhost
device backends for other guests.

File descriptor passing is specific to the AF_UNIX vhost-user protocol
transport.  In order to add support for additional transports, it is
necessary to extract transport-specific code from the main vhost-user
code.

This patch introduces struct vhost_transport_ops and associates each
device with a transport.  Core vhost-user code calls into
vhost_transport_ops to perform transport-specific operations.

Notifying callfd is a transport-specific operation, so it belongs to
trans_af_unix.c.

Several more patches follow this one to complete the task of moving
AF_UNIX transport code out of core vhost-user code.

Signed-off-by: Nikos Dragazis <ndragazis@arrikto.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 lib/librte_vhost/Makefile        |  2 +-
 lib/librte_vhost/trans_af_unix.c | 20 ++++++++++++++++++++
 lib/librte_vhost/vhost.c         |  1 +
 lib/librte_vhost/vhost.h         | 34 +++++++++++++++++++++++++++++-----
 4 files changed, 51 insertions(+), 6 deletions(-)
 create mode 100644 lib/librte_vhost/trans_af_unix.c

Comments

Aaron Conole June 19, 2019, 8:14 p.m. | #1
Nikos Dragazis <ndragazis@arrikto.com> writes:

> This is the first of a series of patches, whose purpose is to add
> support for the virtio-vhost-user transport. This is a vhost-user
> transport implementation that is different from the default AF_UNIX
> transport. It uses the virtio-vhost-user PCI device in order to tunnel
> vhost-user protocol messages over virtio. This lets guests act as vhost
> device backends for other guests.
>
> File descriptor passing is specific to the AF_UNIX vhost-user protocol
> transport.  In order to add support for additional transports, it is
> necessary to extract transport-specific code from the main vhost-user
> code.
>
> This patch introduces struct vhost_transport_ops and associates each
> device with a transport.  Core vhost-user code calls into
> vhost_transport_ops to perform transport-specific operations.
>
> Notifying callfd is a transport-specific operation, so it belongs to
> trans_af_unix.c.
>
> Several more patches follow this one to complete the task of moving
> AF_UNIX transport code out of core vhost-user code.
>
> Signed-off-by: Nikos Dragazis <ndragazis@arrikto.com>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---

You'll need to also accommodate the meson build - probably with
something like:

diff --git a/lib/librte_vhost/meson.build b/lib/librte_vhost/meson.build
index 3090bbe08..81b70683b 100644
--- a/lib/librte_vhost/meson.build
+++ b/lib/librte_vhost/meson.build
@@ -14,6 +14,6 @@ allow_experimental_apis = true
 cflags += '-fno-strict-aliasing'
 sources = files('fd_man.c', 'iotlb.c', 'socket.c', 'vdpa.c',
                'vhost.c', 'vhost_user.c',
-               'virtio_net.c', 'vhost_crypto.c')
+               'virtio_net.c', 'vhost_crypto.c', 'trans_af_unix.c')
 headers = files('rte_vhost.h', 'rte_vdpa.h', 'rte_vhost_crypto.h')
 deps += ['ethdev', 'cryptodev', 'hash', 'pci']


>  lib/librte_vhost/Makefile        |  2 +-
>  lib/librte_vhost/trans_af_unix.c | 20 ++++++++++++++++++++
>  lib/librte_vhost/vhost.c         |  1 +
>  lib/librte_vhost/vhost.h         | 34 +++++++++++++++++++++++++++++-----
>  4 files changed, 51 insertions(+), 6 deletions(-)
>  create mode 100644 lib/librte_vhost/trans_af_unix.c
>
> diff --git a/lib/librte_vhost/Makefile b/lib/librte_vhost/Makefile
> index 8623e91..5ff5fb2 100644
> --- a/lib/librte_vhost/Makefile
> +++ b/lib/librte_vhost/Makefile
> @@ -23,7 +23,7 @@ LDLIBS += -lrte_eal -lrte_mempool -lrte_mbuf -lrte_ethdev -lrte_net
>  
>  # all source are stored in SRCS-y
>  SRCS-$(CONFIG_RTE_LIBRTE_VHOST) := fd_man.c iotlb.c socket.c vhost.c \
> -					vhost_user.c virtio_net.c vdpa.c
> +					vhost_user.c virtio_net.c vdpa.c trans_af_unix.c
>  
>  # install includes
>  SYMLINK-$(CONFIG_RTE_LIBRTE_VHOST)-include += rte_vhost.h rte_vdpa.h
> diff --git a/lib/librte_vhost/trans_af_unix.c b/lib/librte_vhost/trans_af_unix.c
> new file mode 100644
> index 0000000..3f0c308
> --- /dev/null
> +++ b/lib/librte_vhost/trans_af_unix.c
> @@ -0,0 +1,20 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2010-2018 Intel Corporation
> + * Copyright(c) 2017 Red Hat, Inc.
> + * Copyright(c) 2019 Arrikto Inc.
> + */
> +
> +#include "vhost.h"
> +
> +static int
> +af_unix_vring_call(struct virtio_net *dev __rte_unused,
> +		   struct vhost_virtqueue *vq)
> +{
> +	if (vq->callfd >= 0)
> +		eventfd_write(vq->callfd, (eventfd_t)1);
> +	return 0;
> +}
> +
> +const struct vhost_transport_ops af_unix_trans_ops = {
> +	.vring_call = af_unix_vring_call,
> +};
> diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
> index 981837b..a36bc01 100644
> --- a/lib/librte_vhost/vhost.c
> +++ b/lib/librte_vhost/vhost.c
> @@ -507,6 +507,7 @@ vhost_new_device(void)
>  	dev->vid = i;
>  	dev->flags = VIRTIO_DEV_BUILTIN_VIRTIO_NET;
>  	dev->slave_req_fd = -1;
> +	dev->trans_ops = &af_unix_trans_ops;
>  	dev->vdpa_dev_id = -1;
>  	dev->postcopy_ufd = -1;
>  	rte_spinlock_init(&dev->slave_req_lock);
> diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
> index 884befa..077f213 100644
> --- a/lib/librte_vhost/vhost.h
> +++ b/lib/librte_vhost/vhost.h
> @@ -286,6 +286,30 @@ struct guest_page {
>  	uint64_t size;
>  };
>  
> +struct virtio_net;
> +
> +/**
> + * A structure containing function pointers for transport-specific operations.
> + */
> +struct vhost_transport_ops {
> +	/**
> +	 * Notify the guest that used descriptors have been added to the vring.
> +	 * The VRING_AVAIL_F_NO_INTERRUPT flag and event idx have already been checked
> +	 * so this function just needs to perform the notification.
> +	 *
> +	 * @param dev
> +	 *  vhost device
> +	 * @param vq
> +	 *  vhost virtqueue
> +	 * @return
> +	 *  0 on success, -1 on failure
> +	 */
> +	int (*vring_call)(struct virtio_net *dev, struct vhost_virtqueue *vq);
> +};
> +
> +/** The traditional AF_UNIX vhost-user protocol transport. */
> +extern const struct vhost_transport_ops af_unix_trans_ops;
> +
>  /**
>   * Device structure contains all configuration information relating
>   * to the device.
> @@ -312,6 +336,7 @@ struct virtio_net {
>  	uint16_t		mtu;
>  
>  	struct vhost_device_ops const *notify_ops;
> +	struct vhost_transport_ops const *trans_ops;
>  
>  	uint32_t		nr_guest_pages;
>  	uint32_t		max_guest_pages;
> @@ -544,12 +569,11 @@ vhost_vring_call_split(struct virtio_net *dev, struct vhost_virtqueue *vq)
>  		if ((vhost_need_event(vhost_used_event(vq), new, old) &&
>  					(vq->callfd >= 0)) ||
>  				unlikely(!signalled_used_valid))
> -			eventfd_write(vq->callfd, (eventfd_t) 1);
> +			dev->trans_ops->vring_call(dev, vq);
>  	} else {
>  		/* Kick the guest if necessary. */
> -		if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
> -				&& (vq->callfd >= 0))
> -			eventfd_write(vq->callfd, (eventfd_t)1);
> +		if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
> +			dev->trans_ops->vring_call(dev, vq);
>  	}
>  }
>  
> @@ -601,7 +625,7 @@ vhost_vring_call_packed(struct virtio_net *dev, struct vhost_virtqueue *vq)
>  		kick = true;
>  kick:
>  	if (kick)
> -		eventfd_write(vq->callfd, (eventfd_t)1);
> +		dev->trans_ops->vring_call(dev, vq);
>  }
>  
>  static __rte_always_inline void
Bruce Richardson June 20, 2019, 10:30 a.m. | #2
On Wed, Jun 19, 2019 at 04:14:09PM -0400, Aaron Conole wrote:
> Nikos Dragazis <ndragazis@arrikto.com> writes:
> 
> > This is the first of a series of patches, whose purpose is to add
> > support for the virtio-vhost-user transport. This is a vhost-user
> > transport implementation that is different from the default AF_UNIX
> > transport. It uses the virtio-vhost-user PCI device in order to tunnel
> > vhost-user protocol messages over virtio. This lets guests act as vhost
> > device backends for other guests.
> >
> > File descriptor passing is specific to the AF_UNIX vhost-user protocol
> > transport.  In order to add support for additional transports, it is
> > necessary to extract transport-specific code from the main vhost-user
> > code.
> >
> > This patch introduces struct vhost_transport_ops and associates each
> > device with a transport.  Core vhost-user code calls into
> > vhost_transport_ops to perform transport-specific operations.
> >
> > Notifying callfd is a transport-specific operation, so it belongs to
> > trans_af_unix.c.
> >
> > Several more patches follow this one to complete the task of moving
> > AF_UNIX transport code out of core vhost-user code.
> >
> > Signed-off-by: Nikos Dragazis <ndragazis@arrikto.com>
> > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> > ---
> 
> You'll need to also accommodate the meson build - probably with
> something like:
> 
> diff --git a/lib/librte_vhost/meson.build b/lib/librte_vhost/meson.build
> index 3090bbe08..81b70683b 100644
> --- a/lib/librte_vhost/meson.build
> +++ b/lib/librte_vhost/meson.build
> @@ -14,6 +14,6 @@ allow_experimental_apis = true
>  cflags += '-fno-strict-aliasing'
>  sources = files('fd_man.c', 'iotlb.c', 'socket.c', 'vdpa.c',
>                 'vhost.c', 'vhost_user.c',
> -               'virtio_net.c', 'vhost_crypto.c')
> +               'virtio_net.c', 'vhost_crypto.c', 'trans_af_unix.c')
>  headers = files('rte_vhost.h', 'rte_vdpa.h', 'rte_vhost_crypto.h')
>  deps += ['ethdev', 'cryptodev', 'hash', 'pci']
> 
> 

Yep, except I think we should try and keep the files in alphabetical order,
with only a couple of entries per line [so place trans_af_unix.c on a new
line with vdpa.c].
Nikos Dragazis June 20, 2019, 6:19 p.m. | #3
On 19/6/19 11:14 μ.μ., Aaron Conole wrote:
> Nikos Dragazis <ndragazis@arrikto.com> writes:
>
>> This is the first of a series of patches, whose purpose is to add
>> support for the virtio-vhost-user transport. This is a vhost-user
>> transport implementation that is different from the default AF_UNIX
>> transport. It uses the virtio-vhost-user PCI device in order to tunnel
>> vhost-user protocol messages over virtio. This lets guests act as vhost
>> device backends for other guests.
>>
>> File descriptor passing is specific to the AF_UNIX vhost-user protocol
>> transport.  In order to add support for additional transports, it is
>> necessary to extract transport-specific code from the main vhost-user
>> code.
>>
>> This patch introduces struct vhost_transport_ops and associates each
>> device with a transport.  Core vhost-user code calls into
>> vhost_transport_ops to perform transport-specific operations.
>>
>> Notifying callfd is a transport-specific operation, so it belongs to
>> trans_af_unix.c.
>>
>> Several more patches follow this one to complete the task of moving
>> AF_UNIX transport code out of core vhost-user code.
>>
>> Signed-off-by: Nikos Dragazis <ndragazis@arrikto.com>
>> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
>> ---
> You'll need to also accommodate the meson build - probably with
> something like:
>
> diff --git a/lib/librte_vhost/meson.build b/lib/librte_vhost/meson.build
> index 3090bbe08..81b70683b 100644
> --- a/lib/librte_vhost/meson.build
> +++ b/lib/librte_vhost/meson.build
> @@ -14,6 +14,6 @@ allow_experimental_apis = true
>  cflags += '-fno-strict-aliasing'
>  sources = files('fd_man.c', 'iotlb.c', 'socket.c', 'vdpa.c',
>                 'vhost.c', 'vhost_user.c',
> -               'virtio_net.c', 'vhost_crypto.c')
> +               'virtio_net.c', 'vhost_crypto.c', 'trans_af_unix.c')
>  headers = files('rte_vhost.h', 'rte_vdpa.h', 'rte_vhost_crypto.h')
>  deps += ['ethdev', 'cryptodev', 'hash', 'pci']

Thanks for the pointer. I will incorporate the change in the second
version of the patch series along with any other potential comments.

>
>
>>  lib/librte_vhost/Makefile        |  2 +-
>>  lib/librte_vhost/trans_af_unix.c | 20 ++++++++++++++++++++
>>  lib/librte_vhost/vhost.c         |  1 +
>>  lib/librte_vhost/vhost.h         | 34 +++++++++++++++++++++++++++++-----
>>  4 files changed, 51 insertions(+), 6 deletions(-)
>>  create mode 100644 lib/librte_vhost/trans_af_unix.c
>>
>> diff --git a/lib/librte_vhost/Makefile b/lib/librte_vhost/Makefile
>> index 8623e91..5ff5fb2 100644
>> --- a/lib/librte_vhost/Makefile
>> +++ b/lib/librte_vhost/Makefile
>> @@ -23,7 +23,7 @@ LDLIBS += -lrte_eal -lrte_mempool -lrte_mbuf -lrte_ethdev -lrte_net
>>  
>>  # all source are stored in SRCS-y
>>  SRCS-$(CONFIG_RTE_LIBRTE_VHOST) := fd_man.c iotlb.c socket.c vhost.c \
>> -					vhost_user.c virtio_net.c vdpa.c
>> +					vhost_user.c virtio_net.c vdpa.c trans_af_unix.c
>>  
>>  # install includes
>>  SYMLINK-$(CONFIG_RTE_LIBRTE_VHOST)-include += rte_vhost.h rte_vdpa.h
>> diff --git a/lib/librte_vhost/trans_af_unix.c b/lib/librte_vhost/trans_af_unix.c
>> new file mode 100644
>> index 0000000..3f0c308
>> --- /dev/null
>> +++ b/lib/librte_vhost/trans_af_unix.c
>> @@ -0,0 +1,20 @@
>> +/* SPDX-License-Identifier: BSD-3-Clause
>> + * Copyright(c) 2010-2018 Intel Corporation
>> + * Copyright(c) 2017 Red Hat, Inc.
>> + * Copyright(c) 2019 Arrikto Inc.
>> + */
>> +
>> +#include "vhost.h"
>> +
>> +static int
>> +af_unix_vring_call(struct virtio_net *dev __rte_unused,
>> +		   struct vhost_virtqueue *vq)
>> +{
>> +	if (vq->callfd >= 0)
>> +		eventfd_write(vq->callfd, (eventfd_t)1);
>> +	return 0;
>> +}
>> +
>> +const struct vhost_transport_ops af_unix_trans_ops = {
>> +	.vring_call = af_unix_vring_call,
>> +};
>> diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
>> index 981837b..a36bc01 100644
>> --- a/lib/librte_vhost/vhost.c
>> +++ b/lib/librte_vhost/vhost.c
>> @@ -507,6 +507,7 @@ vhost_new_device(void)
>>  	dev->vid = i;
>>  	dev->flags = VIRTIO_DEV_BUILTIN_VIRTIO_NET;
>>  	dev->slave_req_fd = -1;
>> +	dev->trans_ops = &af_unix_trans_ops;
>>  	dev->vdpa_dev_id = -1;
>>  	dev->postcopy_ufd = -1;
>>  	rte_spinlock_init(&dev->slave_req_lock);
>> diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
>> index 884befa..077f213 100644
>> --- a/lib/librte_vhost/vhost.h
>> +++ b/lib/librte_vhost/vhost.h
>> @@ -286,6 +286,30 @@ struct guest_page {
>>  	uint64_t size;
>>  };
>>  
>> +struct virtio_net;
>> +
>> +/**
>> + * A structure containing function pointers for transport-specific operations.
>> + */
>> +struct vhost_transport_ops {
>> +	/**
>> +	 * Notify the guest that used descriptors have been added to the vring.
>> +	 * The VRING_AVAIL_F_NO_INTERRUPT flag and event idx have already been checked
>> +	 * so this function just needs to perform the notification.
>> +	 *
>> +	 * @param dev
>> +	 *  vhost device
>> +	 * @param vq
>> +	 *  vhost virtqueue
>> +	 * @return
>> +	 *  0 on success, -1 on failure
>> +	 */
>> +	int (*vring_call)(struct virtio_net *dev, struct vhost_virtqueue *vq);
>> +};
>> +
>> +/** The traditional AF_UNIX vhost-user protocol transport. */
>> +extern const struct vhost_transport_ops af_unix_trans_ops;
>> +
>>  /**
>>   * Device structure contains all configuration information relating
>>   * to the device.
>> @@ -312,6 +336,7 @@ struct virtio_net {
>>  	uint16_t		mtu;
>>  
>>  	struct vhost_device_ops const *notify_ops;
>> +	struct vhost_transport_ops const *trans_ops;
>>  
>>  	uint32_t		nr_guest_pages;
>>  	uint32_t		max_guest_pages;
>> @@ -544,12 +569,11 @@ vhost_vring_call_split(struct virtio_net *dev, struct vhost_virtqueue *vq)
>>  		if ((vhost_need_event(vhost_used_event(vq), new, old) &&
>>  					(vq->callfd >= 0)) ||
>>  				unlikely(!signalled_used_valid))
>> -			eventfd_write(vq->callfd, (eventfd_t) 1);
>> +			dev->trans_ops->vring_call(dev, vq);
>>  	} else {
>>  		/* Kick the guest if necessary. */
>> -		if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
>> -				&& (vq->callfd >= 0))
>> -			eventfd_write(vq->callfd, (eventfd_t)1);
>> +		if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
>> +			dev->trans_ops->vring_call(dev, vq);
>>  	}
>>  }
>>  
>> @@ -601,7 +625,7 @@ vhost_vring_call_packed(struct virtio_net *dev, struct vhost_virtqueue *vq)
>>  		kick = true;
>>  kick:
>>  	if (kick)
>> -		eventfd_write(vq->callfd, (eventfd_t)1);
>> +		dev->trans_ops->vring_call(dev, vq);
>>  }
>>  
>>  static __rte_always_inline void
Nikos Dragazis June 20, 2019, 6:24 p.m. | #4
On 20/6/19 1:30 μ.μ., Bruce Richardson wrote:
> On Wed, Jun 19, 2019 at 04:14:09PM -0400, Aaron Conole wrote:
>> Nikos Dragazis <ndragazis@arrikto.com> writes:
>>
>>> This is the first of a series of patches, whose purpose is to add
>>> support for the virtio-vhost-user transport. This is a vhost-user
>>> transport implementation that is different from the default AF_UNIX
>>> transport. It uses the virtio-vhost-user PCI device in order to tunnel
>>> vhost-user protocol messages over virtio. This lets guests act as vhost
>>> device backends for other guests.
>>>
>>> File descriptor passing is specific to the AF_UNIX vhost-user protocol
>>> transport.  In order to add support for additional transports, it is
>>> necessary to extract transport-specific code from the main vhost-user
>>> code.
>>>
>>> This patch introduces struct vhost_transport_ops and associates each
>>> device with a transport.  Core vhost-user code calls into
>>> vhost_transport_ops to perform transport-specific operations.
>>>
>>> Notifying callfd is a transport-specific operation, so it belongs to
>>> trans_af_unix.c.
>>>
>>> Several more patches follow this one to complete the task of moving
>>> AF_UNIX transport code out of core vhost-user code.
>>>
>>> Signed-off-by: Nikos Dragazis <ndragazis@arrikto.com>
>>> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
>>> ---
>> You'll need to also accommodate the meson build - probably with
>> something like:
>>
>> diff --git a/lib/librte_vhost/meson.build b/lib/librte_vhost/meson.build
>> index 3090bbe08..81b70683b 100644
>> --- a/lib/librte_vhost/meson.build
>> +++ b/lib/librte_vhost/meson.build
>> @@ -14,6 +14,6 @@ allow_experimental_apis = true
>>  cflags += '-fno-strict-aliasing'
>>  sources = files('fd_man.c', 'iotlb.c', 'socket.c', 'vdpa.c',
>>                 'vhost.c', 'vhost_user.c',
>> -               'virtio_net.c', 'vhost_crypto.c')
>> +               'virtio_net.c', 'vhost_crypto.c', 'trans_af_unix.c')
>>  headers = files('rte_vhost.h', 'rte_vdpa.h', 'rte_vhost_crypto.h')
>>  deps += ['ethdev', 'cryptodev', 'hash', 'pci']
>>
>>
> Yep, except I think we should try and keep the files in alphabetical order,
> with only a couple of entries per line [so place trans_af_unix.c on a new
> line with vdpa.c].

Ack

Patch

diff --git a/lib/librte_vhost/Makefile b/lib/librte_vhost/Makefile
index 8623e91..5ff5fb2 100644
--- a/lib/librte_vhost/Makefile
+++ b/lib/librte_vhost/Makefile
@@ -23,7 +23,7 @@  LDLIBS += -lrte_eal -lrte_mempool -lrte_mbuf -lrte_ethdev -lrte_net
 
 # all source are stored in SRCS-y
 SRCS-$(CONFIG_RTE_LIBRTE_VHOST) := fd_man.c iotlb.c socket.c vhost.c \
-					vhost_user.c virtio_net.c vdpa.c
+					vhost_user.c virtio_net.c vdpa.c trans_af_unix.c
 
 # install includes
 SYMLINK-$(CONFIG_RTE_LIBRTE_VHOST)-include += rte_vhost.h rte_vdpa.h
diff --git a/lib/librte_vhost/trans_af_unix.c b/lib/librte_vhost/trans_af_unix.c
new file mode 100644
index 0000000..3f0c308
--- /dev/null
+++ b/lib/librte_vhost/trans_af_unix.c
@@ -0,0 +1,20 @@ 
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2010-2018 Intel Corporation
+ * Copyright(c) 2017 Red Hat, Inc.
+ * Copyright(c) 2019 Arrikto Inc.
+ */
+
+#include "vhost.h"
+
+static int
+af_unix_vring_call(struct virtio_net *dev __rte_unused,
+		   struct vhost_virtqueue *vq)
+{
+	if (vq->callfd >= 0)
+		eventfd_write(vq->callfd, (eventfd_t)1);
+	return 0;
+}
+
+const struct vhost_transport_ops af_unix_trans_ops = {
+	.vring_call = af_unix_vring_call,
+};
diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
index 981837b..a36bc01 100644
--- a/lib/librte_vhost/vhost.c
+++ b/lib/librte_vhost/vhost.c
@@ -507,6 +507,7 @@  vhost_new_device(void)
 	dev->vid = i;
 	dev->flags = VIRTIO_DEV_BUILTIN_VIRTIO_NET;
 	dev->slave_req_fd = -1;
+	dev->trans_ops = &af_unix_trans_ops;
 	dev->vdpa_dev_id = -1;
 	dev->postcopy_ufd = -1;
 	rte_spinlock_init(&dev->slave_req_lock);
diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
index 884befa..077f213 100644
--- a/lib/librte_vhost/vhost.h
+++ b/lib/librte_vhost/vhost.h
@@ -286,6 +286,30 @@  struct guest_page {
 	uint64_t size;
 };
 
+struct virtio_net;
+
+/**
+ * A structure containing function pointers for transport-specific operations.
+ */
+struct vhost_transport_ops {
+	/**
+	 * Notify the guest that used descriptors have been added to the vring.
+	 * The VRING_AVAIL_F_NO_INTERRUPT flag and event idx have already been checked
+	 * so this function just needs to perform the notification.
+	 *
+	 * @param dev
+	 *  vhost device
+	 * @param vq
+	 *  vhost virtqueue
+	 * @return
+	 *  0 on success, -1 on failure
+	 */
+	int (*vring_call)(struct virtio_net *dev, struct vhost_virtqueue *vq);
+};
+
+/** The traditional AF_UNIX vhost-user protocol transport. */
+extern const struct vhost_transport_ops af_unix_trans_ops;
+
 /**
  * Device structure contains all configuration information relating
  * to the device.
@@ -312,6 +336,7 @@  struct virtio_net {
 	uint16_t		mtu;
 
 	struct vhost_device_ops const *notify_ops;
+	struct vhost_transport_ops const *trans_ops;
 
 	uint32_t		nr_guest_pages;
 	uint32_t		max_guest_pages;
@@ -544,12 +569,11 @@  vhost_vring_call_split(struct virtio_net *dev, struct vhost_virtqueue *vq)
 		if ((vhost_need_event(vhost_used_event(vq), new, old) &&
 					(vq->callfd >= 0)) ||
 				unlikely(!signalled_used_valid))
-			eventfd_write(vq->callfd, (eventfd_t) 1);
+			dev->trans_ops->vring_call(dev, vq);
 	} else {
 		/* Kick the guest if necessary. */
-		if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
-				&& (vq->callfd >= 0))
-			eventfd_write(vq->callfd, (eventfd_t)1);
+		if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
+			dev->trans_ops->vring_call(dev, vq);
 	}
 }
 
@@ -601,7 +625,7 @@  vhost_vring_call_packed(struct virtio_net *dev, struct vhost_virtqueue *vq)
 		kick = true;
 kick:
 	if (kick)
-		eventfd_write(vq->callfd, (eventfd_t)1);
+		dev->trans_ops->vring_call(dev, vq);
 }
 
 static __rte_always_inline void