[Sound-open-firmware] [PATCH v7 3/3] vhost: add an RPMsg API
Guennadi Liakhovetski
guennadi.liakhovetski at linux.intel.com
Thu Sep 10 13:13:51 CEST 2020
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.
Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski at linux.intel.com>
---
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.
+
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 at linux.intel.com>
+ *
+ * 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>
+#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);
+
+ 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 */
+ 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;
+ }
+
+ 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;
+
+ 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() */
+ };
+ 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 at linux.intel.com>
+ */
+
+#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 */
+ /* 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
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