Re: [PATCH v3 5/5] vhost: add an RPMsg API
On Thu, Jun 18, 2020 at 04:14:12PM +0200, Guennadi Liakhovetski wrote: > On Thu, Jun 18, 2020 at 03:52:42PM +0200, Vincent Whitchurch wrote: > > Note that "the Linux side" is ambiguous for AMP since both sides can be > > Linux, as they happen to be in my case. I'm running virtio/rpmsg > > between two physical processors (of different architectures), both > > running Linux. > > Ok, interesting, I didn't know such configurations were used too. I > understood > the Linux rpmsg implementation in the way, that it's assumed, that the "host" > has to boot the "device" by sending an ELF formatted executable image to it, > is > that optional? You aren't sending a complete Linux image to the device side, > are you? I do pack the zImage, the dtb, and the initramfs into an ELF (along with a tiny "bootloader" with just a handful of instructions), but the remoteproc framework is not tied to the ELF format since ->parse_fw() and friends are overridable by the remoteproc driver. > > virtio has distinct driver and device roles so the completely different > > APIs on each side are understandable. But I don't see that distinction > > in the rpmsg API which is why it seems like a good idea to me to make it > > work from both sides of the link and allow the reuse of drivers like > > rpmsg-char, instead of imposing virtio's distinction on rpmsg. > > Understand. In principle I'm open to this idea, but before I implement it it > would be good to know what maintainers think? Certainly. ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v3 5/5] vhost: add an RPMsg API
On Thu, Jun 18, 2020 at 03:52:42PM +0200, Vincent Whitchurch wrote: > On Thu, Jun 18, 2020 at 12:39:40PM +0200, Guennadi Liakhovetski wrote: > > On Thu, Jun 18, 2020 at 11:33:24AM +0200, Vincent Whitchurch wrote: > > > By the "normal rpmsg API" I mean register_rpmsg_driver(), rpmsg_send(), > > > etc. That API is not tied to virtio in any way and there are other > > > non-virtio backends for this API in the tree. So it seems quite natural > > > to implement a vhost backend for this API so that both sides of the link > > > can use the same API but different backends, instead of forcing them to > > > use of different APIs. > > > > Ok, I see what you mean now. But I'm not sure this is useful or desired. > > I'm > > not an expert in KVM / VirtIO, I've only been working in the area for less > > than a year, so, I might well be wrong. > > > > You're proposing to use the rpmsg API in vhost drivers. As far as I > > understand so far that API was only designated for the Linux side (in case > > of > > AMPs) which corresponds to VM guests in virtualisation case. So, I'm not > > sure > > we want to use the same API for the hosts? This can be done as you have > > illustrated, but is it desirable? The vhost API is far enough from the > > VirtIO > > driver API, so I'm not sure why we want the same API for rpmsg? > > Note that "the Linux side" is ambiguous for AMP since both sides can be > Linux, as they happen to be in my case. I'm running virtio/rpmsg > between two physical processors (of different architectures), both > running Linux. Ok, interesting, I didn't know such configurations were used too. I understood the Linux rpmsg implementation in the way, that it's assumed, that the "host" has to boot the "device" by sending an ELF formatted executable image to it, is that optional? You aren't sending a complete Linux image to the device side, are you? > virtio has distinct driver and device roles so the completely different > APIs on each side are understandable. But I don't see that distinction > in the rpmsg API which is why it seems like a good idea to me to make it > work from both sides of the link and allow the reuse of drivers like > rpmsg-char, instead of imposing virtio's distinction on rpmsg. Understand. In principle I'm open to this idea, but before I implement it it would be good to know what maintainers think? Thanks Guennadi ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v3 5/5] vhost: add an RPMsg API
On Thu, Jun 18, 2020 at 12:39:40PM +0200, Guennadi Liakhovetski wrote: > On Thu, Jun 18, 2020 at 11:33:24AM +0200, Vincent Whitchurch wrote: > > By the "normal rpmsg API" I mean register_rpmsg_driver(), rpmsg_send(), > > etc. That API is not tied to virtio in any way and there are other > > non-virtio backends for this API in the tree. So it seems quite natural > > to implement a vhost backend for this API so that both sides of the link > > can use the same API but different backends, instead of forcing them to > > use of different APIs. > > Ok, I see what you mean now. But I'm not sure this is useful or desired. I'm > not an expert in KVM / VirtIO, I've only been working in the area for less > than a year, so, I might well be wrong. > > You're proposing to use the rpmsg API in vhost drivers. As far as I > understand so far that API was only designated for the Linux side (in case of > AMPs) which corresponds to VM guests in virtualisation case. So, I'm not sure > we want to use the same API for the hosts? This can be done as you have > illustrated, but is it desirable? The vhost API is far enough from the VirtIO > driver API, so I'm not sure why we want the same API for rpmsg? Note that "the Linux side" is ambiguous for AMP since both sides can be Linux, as they happen to be in my case. I'm running virtio/rpmsg between two physical processors (of different architectures), both running Linux. virtio has distinct driver and device roles so the completely different APIs on each side are understandable. But I don't see that distinction in the rpmsg API which is why it seems like a good idea to me to make it work from both sides of the link and allow the reuse of drivers like rpmsg-char, instead of imposing virtio's distinction on rpmsg. ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v3 5/5] vhost: add an RPMsg API
On Thu, Jun 18, 2020 at 11:33:24AM +0200, Vincent Whitchurch wrote:
> On Thu, Jun 18, 2020 at 11:03:42AM +0200, Guennadi Liakhovetski wrote:
> > On Wed, Jun 17, 2020 at 09:17:42PM +0200, Vincent Whitchurch wrote:
> > > On Wed, May 27, 2020 at 08:05:41PM +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 a VirtIO server. This patch adds a vhost-based RPMsg
> > > > server implementation.
> > >
> > > This looks really useful, but why is it implemented as an API and not as
> > > a real vhost driver which implements an rpmsg bus? If you implement it
> > > as a vhost driver which implements rpmsg_device_ops and
> > > rpmsg_endpoint_ops, then wouldn't you be able to implement your
> > > vhost-sof driver using the normal rpmsg APIs?
> >
> > Sorry, not sure what you mean by the "normal rpmsg API?" Do you mean the
> > VirtIO RPMsg API? But that's the opposite side of the link - that's the
> > guest side in the VM case and the Linux side in the remoteproc case. What
> > this API is adding is a vhost RPMsg API. The kernel vhost framework
> > itself is essentially a library of functions. Kernel vhost drivers simply
> > create a misc device and use the vhost functions for some common
> > functionality. This RPMsg vhost API stays in the same concept and provides
> > further functions for RPMsg specific vhost operation.
>
> By the "normal rpmsg API" I mean register_rpmsg_driver(), rpmsg_send(),
> etc. That API is not tied to virtio in any way and there are other
> non-virtio backends for this API in the tree. So it seems quite natural
> to implement a vhost backend for this API so that both sides of the link
> can use the same API but different backends, instead of forcing them to
> use of different APIs.
Ok, I see what you mean now. But I'm not sure this is useful or desired. I'm
not an expert in KVM / VirtIO, I've only been working in the area for less
than a year, so, I might well be wrong.
You're proposing to use the rpmsg API in vhost drivers. As far as I
understand so far that API was only designated for the Linux side (in case of
AMPs) which corresponds to VM guests in virtualisation case. So, I'm not sure
we want to use the same API for the hosts? This can be done as you have
illustrated, but is it desirable? The vhost API is far enough from the VirtIO
driver API, so I'm not sure why we want the same API for rpmsg?
Thanks
Guennadi
> > > I tried quickly hooking up this code to such a vhost driver and I was
> > > able to communicate between host and guest systems with both
> > > rpmsg-client-sample and rpmsg-char which almost no modifications to
> > > those drivers.
> >
> > You mean you used this patch to create RPMsg vhost drivers? Without
> > creating a vhost RPMsg bus? Nice, glad to hear that!
>
> Not quite, I hacked togther a single generic vhost-rpmsg-bus driver
> which just wraps the API in this patch and implements a basic
> rpmsg_device_ops and rpmsg_endpoint_ops. Then with the following
> patches and no other vhost-specific API use, I was able to load and use
> the same rpmsg-char and rpmsg-client-sample drivers on both host and
> guest kernels.
>
> Userspace sets up the vhost using vhost-rpmsg-bus' misc device and
> triggers creation of an rpdev which leads to a probe of the (for
> example) rpmsg-client-sample driver on the host (server), which, in
> turn, via NS announcement, triggers a creation of an rpdev and a probe
> of the rpmsg-client-sample driver on the guest (client).
>
> diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
> index a76b963a7e5..7a03978d002 100644
> --- a/drivers/rpmsg/rpmsg_char.c
> +++ b/drivers/rpmsg/rpmsg_char.c
> @@ -104,6 +104,11 @@ static int rpmsg_ept_cb(struct rpmsg_device *rpdev, void
> *buf, int len,
> struct rpmsg_eptdev *eptdev = priv;
> struct sk_buff *skb;
>
> + if (rpdev->dst == RPMSG_ADDR_ANY) {
> + printk("%s: got client address %#x from first rx!\n", __func__,
> addr);
> + rpdev->dst = addr;
> + }
> +
> skb = alloc_skb(len, GFP_ATOMIC);
> if (!skb)
> return -ENOMEM;
> @@ -235,6 +240,12 @@ static ssize_t rpmsg_eptdev_write(struct file *filp,
> const char __user *buf,
> goto unlock_eptdev;
> }
>
> + if (eptdev->rpdev->dst == RPMSG_ADDR_ANY) {
> + ret = -EPIPE;
> + WARN(1, "Cannot write first on server, must wait for
> client!\n");
> + goto unlock_eptdev;
> + }
> +
> if (filp->f_flags & O_NONBLOCK)
> ret = rpmsg_trysend(eptdev->ept, kbuf, len);
> else
> diff --git a/samples/rpmsg/rpmsg_client_sample.c
> b/samples/rpmsg/rpmsg_client_sample.c
> index f161dfd3e70..5d8ca84dce0 100644
> --- a/samples/rpmsg/rpmsg_client_sample.c
> +++ b/samples/rpmsg/rpmsg_client_sample.c
> @@ -46,6 +46,9 @@ static int
Re: [PATCH v3 5/5] vhost: add an RPMsg API
On Thu, Jun 18, 2020 at 11:03:42AM +0200, Guennadi Liakhovetski wrote:
> On Wed, Jun 17, 2020 at 09:17:42PM +0200, Vincent Whitchurch wrote:
> > On Wed, May 27, 2020 at 08:05:41PM +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 a VirtIO server. This patch adds a vhost-based RPMsg
> > > server implementation.
> >
> > This looks really useful, but why is it implemented as an API and not as
> > a real vhost driver which implements an rpmsg bus? If you implement it
> > as a vhost driver which implements rpmsg_device_ops and
> > rpmsg_endpoint_ops, then wouldn't you be able to implement your
> > vhost-sof driver using the normal rpmsg APIs?
>
> Sorry, not sure what you mean by the "normal rpmsg API?" Do you mean the
> VirtIO RPMsg API? But that's the opposite side of the link - that's the
> guest side in the VM case and the Linux side in the remoteproc case. What
> this API is adding is a vhost RPMsg API. The kernel vhost framework
> itself is essentially a library of functions. Kernel vhost drivers simply
> create a misc device and use the vhost functions for some common
> functionality. This RPMsg vhost API stays in the same concept and provides
> further functions for RPMsg specific vhost operation.
By the "normal rpmsg API" I mean register_rpmsg_driver(), rpmsg_send(),
etc. That API is not tied to virtio in any way and there are other
non-virtio backends for this API in the tree. So it seems quite natural
to implement a vhost backend for this API so that both sides of the link
can use the same API but different backends, instead of forcing them to
use of different APIs.
> > I tried quickly hooking up this code to such a vhost driver and I was
> > able to communicate between host and guest systems with both
> > rpmsg-client-sample and rpmsg-char which almost no modifications to
> > those drivers.
>
> You mean you used this patch to create RPMsg vhost drivers? Without
> creating a vhost RPMsg bus? Nice, glad to hear that!
Not quite, I hacked togther a single generic vhost-rpmsg-bus driver
which just wraps the API in this patch and implements a basic
rpmsg_device_ops and rpmsg_endpoint_ops. Then with the following
patches and no other vhost-specific API use, I was able to load and use
the same rpmsg-char and rpmsg-client-sample drivers on both host and
guest kernels.
Userspace sets up the vhost using vhost-rpmsg-bus' misc device and
triggers creation of an rpdev which leads to a probe of the (for
example) rpmsg-client-sample driver on the host (server), which, in
turn, via NS announcement, triggers a creation of an rpdev and a probe
of the rpmsg-client-sample driver on the guest (client).
diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
index a76b963a7e5..7a03978d002 100644
--- a/drivers/rpmsg/rpmsg_char.c
+++ b/drivers/rpmsg/rpmsg_char.c
@@ -104,6 +104,11 @@ static int rpmsg_ept_cb(struct rpmsg_device *rpdev, void
*buf, int len,
struct rpmsg_eptdev *eptdev = priv;
struct sk_buff *skb;
+ if (rpdev->dst == RPMSG_ADDR_ANY) {
+ printk("%s: got client address %#x from first rx!\n", __func__,
addr);
+ rpdev->dst = addr;
+ }
+
skb = alloc_skb(len, GFP_ATOMIC);
if (!skb)
return -ENOMEM;
@@ -235,6 +240,12 @@ static ssize_t rpmsg_eptdev_write(struct file *filp, const
char __user *buf,
goto unlock_eptdev;
}
+ if (eptdev->rpdev->dst == RPMSG_ADDR_ANY) {
+ ret = -EPIPE;
+ WARN(1, "Cannot write first on server, must wait for
client!\n");
+ goto unlock_eptdev;
+ }
+
if (filp->f_flags & O_NONBLOCK)
ret = rpmsg_trysend(eptdev->ept, kbuf, len);
else
diff --git a/samples/rpmsg/rpmsg_client_sample.c
b/samples/rpmsg/rpmsg_client_sample.c
index f161dfd3e70..5d8ca84dce0 100644
--- a/samples/rpmsg/rpmsg_client_sample.c
+++ b/samples/rpmsg/rpmsg_client_sample.c
@@ -46,6 +46,9 @@ static int rpmsg_sample_cb(struct rpmsg_device *rpdev, void
*data, int len,
return 0;
}
+ if (rpdev->dst == RPMSG_ADDR_ANY)
+ rpdev->dst = src;
+
/* send a new message now */
ret = rpmsg_send(rpdev->ept, MSG, strlen(MSG));
if (ret)
@@ -68,11 +71,13 @@ static int rpmsg_sample_probe(struct rpmsg_device *rpdev)
dev_set_drvdata(&rpdev->dev, idata);
- /* send a message to our remote processor */
- ret = rpmsg_send(rpdev->ept, MSG, strlen(MSG));
- if (ret) {
- dev_err(&rpdev->dev, "rpmsg_send failed: %d\n", ret);
- return ret;
+ if (rpdev->dst != RPMSG_ADDR_ANY) {
+ /* send a message to our remote processor */
+ ret = rpmsg_send(rpdev->ept, MSG, strlen(MSG));
+ if (ret) {
+
Re: [PATCH v3 5/5] vhost: add an RPMsg API
Hi Vincent, On Wed, Jun 17, 2020 at 09:17:42PM +0200, Vincent Whitchurch wrote: > On Wed, May 27, 2020 at 08:05:41PM +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 a VirtIO server. This patch adds a vhost-based RPMsg > > server implementation. > > This looks really useful, but why is it implemented as an API and not as > a real vhost driver which implements an rpmsg bus? If you implement it > as a vhost driver which implements rpmsg_device_ops and > rpmsg_endpoint_ops, then wouldn't you be able to implement your > vhost-sof driver using the normal rpmsg APIs? Sorry, not sure what you mean by the "normal rpmsg API?" Do you mean the VirtIO RPMsg API? But that's the opposite side of the link - that's the guest side in the VM case and the Linux side in the remoteproc case. What this API is adding is a vhost RPMsg API. The kernel vhost framework itself is essentially a library of functions. Kernel vhost drivers simply create a misc device and use the vhost functions for some common functionality. This RPMsg vhost API stays in the same concept and provides further functions for RPMsg specific vhost operation. > I tried quickly hooking up this code to such a vhost driver and I was > able to communicate between host and guest systems with both > rpmsg-client-sample and rpmsg-char which almost no modifications to > those drivers. You mean you used this patch to create RPMsg vhost drivers? Without creating a vhost RPMsg bus? Nice, glad to hear that! Thanks Guennadi ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v3 5/5] vhost: add an RPMsg API
On Wed, May 27, 2020 at 08:05:41PM +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 a VirtIO server. This patch adds a vhost-based RPMsg > server implementation. This looks really useful, but why is it implemented as an API and not as a real vhost driver which implements an rpmsg bus? If you implement it as a vhost driver which implements rpmsg_device_ops and rpmsg_endpoint_ops, then wouldn't you be able to implement your vhost-sof driver using the normal rpmsg APIs? I tried quickly hooking up this code to such a vhost driver and I was able to communicate between host and guest systems with both rpmsg-client-sample and rpmsg-char which almost no modifications to those drivers. ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
[PATCH v3 5/5] vhost: add an RPMsg API
Linux supports running the RPMsg protocol over the VirtIO transport
protocol, but currently there is only support for VirtIO clients and
no support for a VirtIO server. This patch adds a vhost-based RPMsg
server implementation.
Signed-off-by: Guennadi Liakhovetski
---
drivers/vhost/Kconfig | 7 +
drivers/vhost/Makefile | 3 +
drivers/vhost/rpmsg.c | 382
drivers/vhost/vhost_rpmsg.h | 74 +
4 files changed, 466 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 2c75d16..8b91f3e 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
+ depends on VHOST
+ help
+ Vhost RPMsg API allows vhost drivers to communicate with VirtIO
+ drivers, 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 f3e1897..9cf459d 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 ..ea77e1f
--- /dev/null
+++ b/drivers/vhost/rpmsg.c
@@ -0,0 +1,382 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright(c) 2020 Intel Corporation. All rights reserved.
+ *
+ * Author: Guennadi Liakhovetski
+ *
+ * Vhost RPMsg VirtIO interface. It provides a set of functions to match the
+ * guest side RPMsg VirtIO API, provided by drivers/rpmsg/virtio_rpmsg_bus.c
+ * These functions handle creation of 2 virtual queues, handling of endpoint
+ * addresses, sending a name-space announcement to the guest as well as any
+ * user messages. This API can be used by any vhost driver to handle RPMsg
+ * specific processing.
+ * Specific 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
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+
+#include "vhost.h"
+#include "vhost_rpmsg.h"
+
+/*
+ * All virtio-rpmsg virtual queue kicks always come with just one buffer -
+ * either input or output
+ */
+static int vhost_rpmsg_get_single(struct vhost_virtqueue *vq)
+{
+ 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] && (out || in != 1)) {
+ vq_err(vq,
+ "%s(): invalid %d input and %d output in response
queue\n",
+ __func__, in, out);
+ goto return_buf;
+ }
+
+ if (vq == &vr->vq[VIRTIO_RPMSG_REQUEST] && (in || out != 1)) {
+ vq_err(vq,
+ "%s(): invalid %d input and %d output in request
queue\n",
+ __func__, in, out);
+ goto return_buf;
+ }
+
+ return head;
+
+return_buf:
+ /*
+* FIXME: might need to return the buffer using vhost_add_used()
+* or vhost_discard_vq_desc(). vhost_discard_vq_desc() is
+* described as "being useful for error handling," but it makes
+* the thus discarded buffers "unseen," so next time we look we
+* retrieve them again?
+*/
+ 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;
+ size_t tmp;
+
+ if (qid >=
