On Fri, Sep 18, 2020 at 11:02:29AM +0200, Guennadi Liakhovetski wrote:
> Hi Mathieu,
>
> On Thu, Sep 17, 2020 at 04:01:38PM -0600, Mathieu Poirier wrote:
> > On Thu, Sep 10, 2020 at 01:13:51PM +0200, Guennadi Liakhovetski wrote:
> > > Linux supports running the RPMsg protocol over the VirtIO transport
> > > protocol, but currently there is only support for VirtIO clients and
> > > no support for VirtIO servers. This patch adds a vhost-based RPMsg
> > > server implementation, which makes it possible to use RPMsg over
> > > VirtIO between guest VMs and the host.
> >
> > I now get the client/server concept you are describing above but that happened
> > only after a lot of mental gymnastics. If you drop the whole client/server
> > concept and concentrate on what this patch does, things will go better. I would
> > personally go with what you have in the Kconfig:
> >
> > > + Vhost RPMsg API allows vhost drivers to communicate with VirtIO
> > > + drivers on guest VMs, using the RPMsg over VirtIO protocol.
> >
> > It is concise but describes exactly what this patch provide.
>
> Ok, thanks, will try to improve.
>
> > > Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@xxxxxxxxxxxxxxx>
> > > ---
> > > drivers/vhost/Kconfig | 7 +
> > > drivers/vhost/Makefile | 3 +
> > > drivers/vhost/rpmsg.c | 370 ++++++++++++++++++++++++++++++++++++
> > > drivers/vhost/vhost_rpmsg.h | 74 ++++++++
> > > 4 files changed, 454 insertions(+)
> > > create mode 100644 drivers/vhost/rpmsg.c
> > > create mode 100644 drivers/vhost/vhost_rpmsg.h
> > >
> > > diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
> > > index 587fbae06182..ee1a19b7ab3d 100644
> > > --- a/drivers/vhost/Kconfig
> > > +++ b/drivers/vhost/Kconfig
> > > @@ -38,6 +38,13 @@ config VHOST_NET
> > > To compile this driver as a module, choose M here: the module will
> > > be called vhost_net.
> > >
> > > +config VHOST_RPMSG
> > > + tristate
> > > + select VHOST
> > > + help
> > > + Vhost RPMsg API allows vhost drivers to communicate with VirtIO
> > > + drivers on guest VMs, using the RPMsg over VirtIO protocol.
> > > +
> >
> > I suppose you intend this to be selectable from another config option?
>
> yes.
>
> > > config VHOST_SCSI
> > > tristate "VHOST_SCSI TCM fabric driver"
> > > depends on TARGET_CORE && EVENTFD
> > > diff --git a/drivers/vhost/Makefile b/drivers/vhost/Makefile
> > > index f3e1897cce85..9cf459d59f97 100644
> > > --- a/drivers/vhost/Makefile
> > > +++ b/drivers/vhost/Makefile
> > > @@ -2,6 +2,9 @@
> > > obj-$(CONFIG_VHOST_NET) += vhost_net.o
> > > vhost_net-y := net.o
> > >
> > > +obj-$(CONFIG_VHOST_RPMSG) += vhost_rpmsg.o
> > > +vhost_rpmsg-y := rpmsg.o
> > > +
> > > obj-$(CONFIG_VHOST_SCSI) += vhost_scsi.o
> > > vhost_scsi-y := scsi.o
> > >
> > > diff --git a/drivers/vhost/rpmsg.c b/drivers/vhost/rpmsg.c
> > > new file mode 100644
> > > index 000000000000..0ddee5b5f017
> > > --- /dev/null
> > > +++ b/drivers/vhost/rpmsg.c
> > > @@ -0,0 +1,370 @@
> > > +// SPDX-License-Identifier: GPL-2.0-only
> > > +/*
> > > + * Copyright(c) 2020 Intel Corporation. All rights reserved.
> > > + *
> > > + * Author: Guennadi Liakhovetski <guennadi.liakhovetski@xxxxxxxxxxxxxxx>
> > > + *
> > > + * Vhost RPMsg VirtIO interface provides a set of functions to be used on the
> > > + * host side as a counterpart to the guest side RPMsg VirtIO API, provided by
> > > + * drivers/rpmsg/virtio_rpmsg_bus.c. This API can be used by any vhost driver to
> > > + * handle RPMsg specific virtqueue processing.
> > > + * Vhost drivers, using this API will use their own VirtIO device IDs, that
> > > + * should then also be added to the ID table in virtio_rpmsg_bus.c
> > > + */
> > > +
> > > +#include <linux/compat.h>
> > > +#include <linux/file.h>
> > > +#include <linux/miscdevice.h>
> >
> > As far as I can tell the above two are not needed.
>
> Look like left-over, will remove.
>
> > > +#include <linux/module.h>
> > > +#include <linux/mutex.h>
> > > +#include <linux/rpmsg/virtio.h>
> > > +#include <linux/vhost.h>
> > > +#include <uapi/linux/rpmsg.h>
> > > +
> > > +#include "vhost.h"
> > > +#include "vhost_rpmsg.h"
> > > +
> > > +/*
> > > + * All virtio-rpmsg virtual queue kicks always come with just one buffer -
> > > + * either input or output, but we can also handle split messages
> > > + */
> > > +static int vhost_rpmsg_get_msg(struct vhost_virtqueue *vq, unsigned int *cnt)
> > > +{
> > > + struct vhost_rpmsg *vr = container_of(vq->dev, struct vhost_rpmsg, dev);
> > > + unsigned int out, in;
> > > + int head = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov), &out, &in,
> > > + NULL, NULL);
> > > + if (head < 0) {
> > > + vq_err(vq, "%s(): error %d getting buffer\n",
> > > + __func__, head);
> > > + return head;
> > > + }
> > > +
> > > + /* Nothing new? */
> > > + if (head == vq->num)
> > > + return head;
> > > +
> > > + if (vq == &vr->vq[VIRTIO_RPMSG_RESPONSE]) {
> > > + if (out) {
> > > + vq_err(vq, "%s(): invalid %d output in response queue\n",
> > > + __func__, out);
> > > + goto return_buf;
> > > + }
> > > +
> > > + *cnt = in;
> > > + }
> > > +
> > > + if (vq == &vr->vq[VIRTIO_RPMSG_REQUEST]) {
> > > + if (in) {
> > > + vq_err(vq, "%s(): invalid %d input in request queue\n",
> > > + __func__, in);
> > > + goto return_buf;
> > > + }
> > > +
> > > + *cnt = out;
> > > + }
> > > +
> > > + return head;
> > > +
> > > +return_buf:
> > > + vhost_add_used(vq, head, 0);
> > > +
> > > + return -EINVAL;
> > > +}
> > > +
> > > +static const struct vhost_rpmsg_ept *vhost_rpmsg_ept_find(struct vhost_rpmsg *vr, int addr)
> > > +{
> > > + unsigned int i;
> > > +
> > > + for (i = 0; i < vr->n_epts; i++)
> > > + if (vr->ept[i].addr == addr)
> > > + return vr->ept + i;
> > > +
> > > + return NULL;
> > > +}
> > > +
> > > +/*
> > > + * if len < 0, then for reading a request, the complete virtual queue buffer
> > > + * size is prepared, for sending a response, the length in the iterator is used
> > > + */
> > > +int vhost_rpmsg_start_lock(struct vhost_rpmsg *vr, struct vhost_rpmsg_iter *iter,
> > > + unsigned int qid, ssize_t len)
> > > + __acquires(vq->mutex)
> > > +{
> > > + struct vhost_virtqueue *vq = vr->vq + qid;
> > > + unsigned int cnt;
> > > + ssize_t ret;
> > > + size_t tmp;
> > > +
> > > + if (qid >= VIRTIO_RPMSG_NUM_OF_VQS)
> > > + return -EINVAL;
> > > +
> > > + iter->vq = vq;
> > > +
> > > + mutex_lock(&vq->mutex);
> > > + vhost_disable_notify(&vr->dev, vq);
> > > +
> > > + iter->head = vhost_rpmsg_get_msg(vq, &cnt);
> > > + if (iter->head == vq->num)
> > > + iter->head = -EAGAIN;
> > > +
> > > + if (iter->head < 0) {
> > > + ret = iter->head;
> > > + goto unlock;
> > > + }
> > > +
> > > + tmp = iov_length(vq->iov, cnt);
> > > + if (tmp < sizeof(iter->rhdr)) {
> > > + vq_err(vq, "%s(): size %zu too small\n", __func__, tmp);
> > > + ret = -ENOBUFS;
> > > + goto return_buf;
> > > + }
> > > +
> > > + switch (qid) {
> > > + case VIRTIO_RPMSG_REQUEST:
> > > + if (len >= 0) {
> > > + if (tmp < sizeof(iter->rhdr) + len) {
> > > + ret = -ENOBUFS;
> > > + goto return_buf;
> > > + }
> > > +
> > > + tmp = len + sizeof(iter->rhdr);
> > > + }
> > > +
> > > + /* len is now the size of the payload */
> > > + iov_iter_init(&iter->iov_iter, WRITE, vq->iov, cnt, tmp);
> > > +
> > > + /* Read the RPMSG header with endpoint addresses */
> > > + tmp = copy_from_iter(&iter->rhdr, sizeof(iter->rhdr), &iter->iov_iter);
> > > + if (tmp != sizeof(iter->rhdr)) {
> > > + vq_err(vq, "%s(): got %zu instead of %zu\n", __func__,
> > > + tmp, sizeof(iter->rhdr));
> > > + ret = -EIO;
> > > + goto return_buf;
> > > + }
> > > +
> > > + iter->ept = vhost_rpmsg_ept_find(vr, vhost32_to_cpu(vq, iter->rhdr.dst));
> > > + if (!iter->ept) {
> > > + vq_err(vq, "%s(): no endpoint with address %d\n",
> > > + __func__, vhost32_to_cpu(vq, iter->rhdr.dst));
> > > + ret = -ENOENT;
> > > + goto return_buf;
> > > + }
> > > +
> > > + /* Let the endpoint read the payload */
> > > + if (iter->ept->read) {
> > > + ret = iter->ept->read(vr, iter);
> > > + if (ret < 0)
> > > + goto return_buf;
> > > +
> > > + iter->rhdr.len = cpu_to_vhost16(vq, ret);
> > > + } else {
> > > + iter->rhdr.len = 0;
> > > + }
> > > +
> > > + /* Prepare for the response phase */
> > > + iter->rhdr.dst = iter->rhdr.src;
> > > + iter->rhdr.src = cpu_to_vhost32(vq, iter->ept->addr);
> >
> > I'm a little puzzled here - what will the response look like? And why is it
> > prepared here? From what I can see doing so introduces coupling with function
> > handle_rpmsg_req_single(). I think confirmation of reception should be handled
> > by endpoints rather than in the core.
>
> RPMsg always contain a header, so we keep the header in the iterator. If the
> caller wants to reply to the request, the easiest way to do that is to reuse the
> iterator. In that case obviously you have to swap source and destination
> addresses. This can be done either in the request handler of the API, or by the
> caller, or in the API response handler. It would be silly to have the user do
> that, that would be repeated code. But I agree, it's a bit unclean to modify the
> header before returning it to the user, without knowing, whether the user will
> use it, in which case it might be surprised to see most fields from the request
> unchanged and only addresses swapped. I'll move this to response with a check
> for a reused iterator.
>
> > > +
> > > + break;
> > > + case VIRTIO_RPMSG_RESPONSE:
> > > + if (!iter->ept && iter->rhdr.dst != cpu_to_vhost32(vq, RPMSG_NS_ADDR)) {
> > > + /*
> > > + * Usually the iterator is configured when processing a
> > > + * message on the request queue, but it's also possible
> > > + * to send a message on the response queue without a
> > > + * preceding request, in that case the iterator must
> > > + * contain source and destination addresses.
> > > + */
> > > + iter->ept = vhost_rpmsg_ept_find(vr, vhost32_to_cpu(vq, iter->rhdr.src));
> > > + if (!iter->ept) {
> > > + ret = -ENOENT;
> > > + goto return_buf;
> > > + }
> > > + }
> > > +
> > > + if (len >= 0) {
> > > + if (tmp < sizeof(iter->rhdr) + len) {
> > > + ret = -ENOBUFS;
> > > + goto return_buf;
> > > + }
> > > +
> > > + iter->rhdr.len = cpu_to_vhost16(vq, len);
> > > + tmp = len + sizeof(iter->rhdr);
> > > + }
> > > +
> > > + /* len is now the size of the payload */
> > > + iov_iter_init(&iter->iov_iter, READ, vq->iov, cnt, tmp);
> > > +
> > > + /* Write the RPMSG header with endpoint addresses */
> > > + tmp = copy_to_iter(&iter->rhdr, sizeof(iter->rhdr), &iter->iov_iter);
> > > + if (tmp != sizeof(iter->rhdr)) {
> > > + ret = -EIO;
> > > + goto return_buf;
> > > + }
> > > +
> > > + /* Let the endpoint write the payload */
> >
> > I would specifically mention that namespace payloads are taken care of by
> > vhost_rpmsg_ns_announce(). That makes it easier for people to connect the dots.
>
> Ok
>
> > > + if (iter->ept && iter->ept->write) {
> > > + ret = iter->ept->write(vr, iter);
> > > + if (ret < 0)
> > > + goto return_buf;
> > > + }
> > > +
> > > + break;
> > > + }
> > > +
> > > + return 0;
> > > +
> > > +return_buf:
> > > + vhost_add_used(vq, iter->head, 0);
> > > +unlock:
> > > + vhost_enable_notify(&vr->dev, vq);
> > > + mutex_unlock(&vq->mutex);
> > > +
> > > + return ret;
> > > +}
> > > +EXPORT_SYMBOL_GPL(vhost_rpmsg_start_lock);
> > > +
> > > +size_t vhost_rpmsg_copy(struct vhost_rpmsg *vr, struct vhost_rpmsg_iter *iter,
> > > + void *data, size_t size)
> > > +{
> > > + /*
> > > + * We could check for excess data, but copy_{to,from}_iter() don't do
> > > + * that either
> > > + */
> > > + if (iter->vq == vr->vq + VIRTIO_RPMSG_RESPONSE)
> > > + return copy_to_iter(data, size, &iter->iov_iter);
> > > +
> > > + return copy_from_iter(data, size, &iter->iov_iter);
> > > +}
> > > +EXPORT_SYMBOL_GPL(vhost_rpmsg_copy);
> > > +
> > > +int vhost_rpmsg_finish_unlock(struct vhost_rpmsg *vr,
> > > + struct vhost_rpmsg_iter *iter)
> > > + __releases(vq->mutex)
> > > +{
> > > + if (iter->head >= 0)
> > > + vhost_add_used_and_signal(iter->vq->dev, iter->vq, iter->head,
> > > + vhost16_to_cpu(iter->vq, iter->rhdr.len) +
> > > + sizeof(iter->rhdr));
> > > +
> > > + vhost_enable_notify(&vr->dev, iter->vq);
> > > + mutex_unlock(&iter->vq->mutex);
> > > +
> > > + return iter->head;
> > > +}
> > > +EXPORT_SYMBOL_GPL(vhost_rpmsg_finish_unlock);
> > > +
> > > +/*
> > > + * Return false to terminate the external loop only if we fail to obtain either
> > > + * a request or a response buffer
> > > + */
> > > +static bool handle_rpmsg_req_single(struct vhost_rpmsg *vr,
> > > + struct vhost_virtqueue *vq)
> > > +{
> > > + struct vhost_rpmsg_iter iter;
> > > + int ret = vhost_rpmsg_start_lock(vr, &iter, VIRTIO_RPMSG_REQUEST, -EINVAL);
> > > + if (!ret)
> > > + ret = vhost_rpmsg_finish_unlock(vr, &iter);
> > > + if (ret < 0) {
> > > + if (ret != -EAGAIN)
> > > + vq_err(vq, "%s(): RPMSG processing failed %d\n",
> > > + __func__, ret);
> > > + return false;
> > > + }
> > > +
> > > + if (!iter.ept->write)
> > > + return true;
> > > +
> > > + ret = vhost_rpmsg_start_lock(vr, &iter, VIRTIO_RPMSG_RESPONSE, -EINVAL);
> > > + if (!ret)
> > > + ret = vhost_rpmsg_finish_unlock(vr, &iter);
> > > + if (ret < 0) {
> > > + vq_err(vq, "%s(): RPMSG finalising failed %d\n", __func__, ret);
> > > + return false;
> > > + }
> >
> > As I said before dealing with the "response" queue here seems to be introducing
> > coupling with vhost_rpmsg_start_lock()... Endpoints should be doing that.
>
> Sorry, could you elaborate a bit, what do you mean by coupling?
>
> > > +
> > > + return true;
> > > +}
> > > +
> > > +static void handle_rpmsg_req_kick(struct vhost_work *work)
> > > +{
> > > + struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
> > > + poll.work);
> > > + struct vhost_rpmsg *vr = container_of(vq->dev, struct vhost_rpmsg, dev);
> > > +
> > > + while (handle_rpmsg_req_single(vr, vq))
> > > + ;
> > > +}
> > > +
> > > +/*
> > > + * initialise two virtqueues with an array of endpoints,
> > > + * request and response callbacks
> > > + */
> > > +void vhost_rpmsg_init(struct vhost_rpmsg *vr, const struct vhost_rpmsg_ept *ept,
> > > + unsigned int n_epts)
> > > +{
> > > + unsigned int i;
> > > +
> > > + for (i = 0; i < ARRAY_SIZE(vr->vq); i++)
> > > + vr->vq_p[i] = &vr->vq[i];
> > > +
> > > + /* vq[0]: host -> guest, vq[1]: host <- guest */
> > > + vr->vq[VIRTIO_RPMSG_REQUEST].handle_kick = handle_rpmsg_req_kick;
> > > + vr->vq[VIRTIO_RPMSG_RESPONSE].handle_kick = NULL;
> >
> > The comment depicts vq[0] followed by vq[1] but the code initialise vq[1] before
> > vq[0], which is wildly confusing. At the very least this should be:
>
> Nobody should care which of those is 0 and which is 1 :-) But indeed you have a point,
> that the protocol isn't strictly request-response based, the host can also send
> messages to the guest without preceding requests. So, TX / RX should be a better fit.
>
> >
> > vr->vq[VIRTIO_RPMSG_RESPONSE].handle_kick = NULL;
> > vr->vq[VIRTIO_RPMSG_REQUEST].handle_kick = handle_rpmsg_req_kick;
> >
> > And even better:
> >
> > /* See configuration of *vq_cbs[] in rpmsg_probe() */
> > vr->vq[VIRTIO_RPMSG_TX].handle_kick = NULL;
> > vr->vq[VIRTIO_RPMSG_RX].handle_kick = handle_rpmsg_req_kick;
> >
> > > +
> > > + vr->ept = ept;
> > > + vr->n_epts = n_epts;
> > > +
> > > + vhost_dev_init(&vr->dev, vr->vq_p, VIRTIO_RPMSG_NUM_OF_VQS,
> > > + UIO_MAXIOV, 0, 0, true, NULL);
> > > +}
> > > +EXPORT_SYMBOL_GPL(vhost_rpmsg_init);
> > > +
> > > +void vhost_rpmsg_destroy(struct vhost_rpmsg *vr)
> > > +{
> > > + if (vhost_dev_has_owner(&vr->dev))
> > > + vhost_poll_flush(&vr->vq[VIRTIO_RPMSG_REQUEST].poll);
> > > +
> > > + vhost_dev_cleanup(&vr->dev);
> > > +}
> > > +EXPORT_SYMBOL_GPL(vhost_rpmsg_destroy);
> > > +
> > > +/* send namespace */
> > > +int vhost_rpmsg_ns_announce(struct vhost_rpmsg *vr, const char *name, unsigned int src)
> > > +{
> > > + struct vhost_virtqueue *vq = &vr->vq[VIRTIO_RPMSG_RESPONSE];
> > > + struct vhost_rpmsg_iter iter = {
> > > + .rhdr = {
> > > + .src = 0,
> > > + .dst = cpu_to_vhost32(vq, RPMSG_NS_ADDR),
> > > + },
> > > + };
> > > + struct rpmsg_ns_msg ns = {
> > > + .addr = cpu_to_vhost32(vq, src),
> > > + .flags = cpu_to_vhost32(vq, RPMSG_NS_CREATE), /* for rpmsg_ns_cb() */
> > > + };
> >
> > Here we have to assume the source can be found in the endpoints registered in
> > vhost_rpmsg_init(). I would put a check to make sure that is the case and
> > return an error otherwise.
>
> Ok, will do.
>
> > > + int ret = vhost_rpmsg_start_lock(vr, &iter, VIRTIO_RPMSG_RESPONSE, sizeof(ns));
> > > +
> > > + if (ret < 0)
> > > + return ret;
> > > +
> > > + strlcpy(ns.name, name, sizeof(ns.name));
> > > +
> > > + ret = vhost_rpmsg_copy(vr, &iter, &ns, sizeof(ns));
> > > + if (ret != sizeof(ns))
> > > + vq_err(iter.vq, "%s(): added %d instead of %zu bytes\n",
> > > + __func__, ret, sizeof(ns));
> > > +
> > > + ret = vhost_rpmsg_finish_unlock(vr, &iter);
> > > + if (ret < 0)
> > > + vq_err(iter.vq, "%s(): namespace announcement failed: %d\n",
> > > + __func__, ret);
> > > +
> > > + return ret;
> > > +}
> > > +EXPORT_SYMBOL_GPL(vhost_rpmsg_ns_announce);
> > > +
> > > +MODULE_LICENSE("GPL v2");
> > > +MODULE_AUTHOR("Intel, Inc.");
> > > +MODULE_DESCRIPTION("Vhost RPMsg API");
> > > diff --git a/drivers/vhost/vhost_rpmsg.h b/drivers/vhost/vhost_rpmsg.h
> > > new file mode 100644
> > > index 000000000000..c020ea14cd16
> > > --- /dev/null
> > > +++ b/drivers/vhost/vhost_rpmsg.h
> > > @@ -0,0 +1,74 @@
> > > +/* SPDX-License-Identifier: GPL-2.0 */
> > > +/*
> > > + * Copyright(c) 2020 Intel Corporation. All rights reserved.
> > > + *
> > > + * Author: Guennadi Liakhovetski <guennadi.liakhovetski@xxxxxxxxxxxxxxx>
> > > + */
> > > +
> > > +#ifndef VHOST_RPMSG_H
> > > +#define VHOST_RPMSG_H
> > > +
> > > +#include <linux/rpmsg/virtio.h>
> > > +#include <linux/uio.h>
> > > +
> > > +#include "vhost.h"
> > > +
> > > +/* RPMsg uses two VirtQueues: one for each direction */
> > > +enum {
> > > + VIRTIO_RPMSG_RESPONSE, /* RPMsg response (host->guest) buffers */
> > > + VIRTIO_RPMSG_REQUEST, /* RPMsg request (guest->host) buffers */
> >
> > As I said above things would be much clearer if this was VIRTIO_RPMSG_TX and
> > VIRTIO_RPMSG_RX.
>
> Ack.
>
> > I won't be commenting on the mechanic needed to access and send information on
> > the virtqueues as it is completely foreign to me. Other than the above I think
> > this is going somewhere.
>
> I'll wait for your clarifications about "coupling" and send a v8.
>
Please hold off on sending another revision. We need to find a solution to keep
rpmsg_hdr and rpmsg_ns_msg generic (see my reply to Arnaud).
Mathieu
> Thanks for the comments so far
> Guennadi
>
> > Thanks,
> > Mathieu
> >
> > > + /* Keep last */
> > > + VIRTIO_RPMSG_NUM_OF_VQS,
> > > +};
> > > +
> > > +struct vhost_rpmsg_ept;
> > > +
> > > +struct vhost_rpmsg_iter {
> > > + struct iov_iter iov_iter;
> > > + struct rpmsg_hdr rhdr;
> > > + struct vhost_virtqueue *vq;
> > > + const struct vhost_rpmsg_ept *ept;
> > > + int head;
> > > + void *priv;
> > > +};
> > > +
> > > +struct vhost_rpmsg {
> > > + struct vhost_dev dev;
> > > + struct vhost_virtqueue vq[VIRTIO_RPMSG_NUM_OF_VQS];
> > > + struct vhost_virtqueue *vq_p[VIRTIO_RPMSG_NUM_OF_VQS];
> > > + const struct vhost_rpmsg_ept *ept;
> > > + unsigned int n_epts;
> > > +};
> > > +
> > > +struct vhost_rpmsg_ept {
> > > + ssize_t (*read)(struct vhost_rpmsg *, struct vhost_rpmsg_iter *);
> > > + ssize_t (*write)(struct vhost_rpmsg *, struct vhost_rpmsg_iter *);
> > > + int addr;
> > > +};
> > > +
> > > +static inline size_t vhost_rpmsg_iter_len(const struct vhost_rpmsg_iter *iter)
> > > +{
> > > + return iter->rhdr.len;
> > > +}
> > > +
> > > +#define VHOST_RPMSG_ITER(_vq, _src, _dst) { \
> > > + .rhdr = { \
> > > + .src = cpu_to_vhost32(_vq, _src), \
> > > + .dst = cpu_to_vhost32(_vq, _dst), \
> > > + }, \
> > > + }
> > > +
> > > +void vhost_rpmsg_init(struct vhost_rpmsg *vr, const struct vhost_rpmsg_ept *ept,
> > > + unsigned int n_epts);
> > > +void vhost_rpmsg_destroy(struct vhost_rpmsg *vr);
> > > +int vhost_rpmsg_ns_announce(struct vhost_rpmsg *vr, const char *name,
> > > + unsigned int src);
> > > +int vhost_rpmsg_start_lock(struct vhost_rpmsg *vr,
> > > + struct vhost_rpmsg_iter *iter,
> > > + unsigned int qid, ssize_t len);
> > > +size_t vhost_rpmsg_copy(struct vhost_rpmsg *vr, struct vhost_rpmsg_iter *iter,
> > > + void *data, size_t size);
> > > +int vhost_rpmsg_finish_unlock(struct vhost_rpmsg *vr,
> > > + struct vhost_rpmsg_iter *iter);
> > > +
> > > +#endif
> > > --
> > > 2.28.0
> > >
