Re: [PATCH 3/3] rpmsg: virtio_rpmsg_bus: get buffer size from config space

From: xiang xiao
Date: Thu May 09 2019 - 09:01:33 EST

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In reply to: Arnaud Pouliquen: "Re: [PATCH 3/3] rpmsg: virtio_rpmsg_bus: get buffer size from config space"
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On Thu, May 9, 2019 at 8:36 PM Arnaud Pouliquen <arnaud.pouliquen@xxxxxx> wrote:
>
> Hello Xiang,
>
> Similar mechanism has been proposed by Loic 2 years ago (link to the
> series here https://lkml.org/lkml/2017/3/28/349).
>
> Did you see them? Regarding history, patches seem just on hold...
>

Just saw this patchset, so it's common problem hit by many vendor,
rpmsg framework need to address it.:)

> Main differences (except interesting RX/TX size split) seems that you
> - don't use the virtio_config_ops->get

virtio_cread call virtio_config_ops->get internally, the ideal is same
for both patch, just the implementation detail is different.

> - define a new feature VIRTIO_RPMSG_F_NS.

I add this flag to keep the compatibility with old remote peer, and
also follow the common virito driver practice.

>
> Regards
> Arnaud
>
>
> On 1/31/19 4:41 PM, Xiang Xiao wrote:
> > 512 bytes isn't always suitable for all case, let firmware
> > maker decide the best value from resource table.
> > enable by VIRTIO_RPMSG_F_BUFSZ feature bit.
> >
> > Signed-off-by: Xiang Xiao <xiaoxiang@xxxxxxxxxx>
> > ---
> > drivers/rpmsg/virtio_rpmsg_bus.c | 50 +++++++++++++++++++++++++--------------
> > include/uapi/linux/virtio_rpmsg.h | 24 +++++++++++++++++++
> > 2 files changed, 56 insertions(+), 18 deletions(-)
> > create mode 100644 include/uapi/linux/virtio_rpmsg.h
> >
> > diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c
> > index 59c4554..049dd97 100644
> > --- a/drivers/rpmsg/virtio_rpmsg_bus.c
> > +++ b/drivers/rpmsg/virtio_rpmsg_bus.c
> > @@ -16,6 +16,7 @@
> > #include <linux/virtio.h>
> > #include <linux/virtio_ids.h>
> > #include <linux/virtio_config.h>
> > +#include <linux/virtio_rpmsg.h>
> > #include <linux/scatterlist.h>
> > #include <linux/dma-mapping.h>
> > #include <linux/slab.h>
> > @@ -38,7 +39,8 @@
> > * @sbufs: kernel address of tx buffers
> > * @num_rbufs: total number of buffers for rx
> > * @num_sbufs: total number of buffers for tx
> > - * @buf_size: size of one rx or tx buffer
> > + * @rbuf_size: size of one rx buffer
> > + * @sbuf_size: size of one tx buffer
> > * @last_sbuf: index of last tx buffer used
> > * @rbufs_dma: dma base addr of rx buffers
> > * @sbufs_dma: dma base addr of tx buffers
> > @@ -61,7 +63,8 @@ struct virtproc_info {
> > void *rbufs, *sbufs;
> > unsigned int num_rbufs;
> > unsigned int num_sbufs;
> > - unsigned int buf_size;
> > + unsigned int rbuf_size;
> > + unsigned int sbuf_size;
> > int last_sbuf;
> > dma_addr_t rbufs_dma;
> > dma_addr_t sbufs_dma;
> > @@ -73,9 +76,6 @@ struct virtproc_info {
> > struct rpmsg_endpoint *ns_ept;
> > };
> >
> > -/* The feature bitmap for virtio rpmsg */
> > -#define VIRTIO_RPMSG_F_NS 0 /* RP supports name service notifications */
> > -
> > /**
> > * struct rpmsg_hdr - common header for all rpmsg messages
> > * @src: source address
> > @@ -452,7 +452,7 @@ static void *get_a_tx_buf(struct virtproc_info *vrp)
> >
> > /* either pick the next unused tx buffer */
> > if (vrp->last_sbuf < vrp->num_sbufs)
> > - ret = vrp->sbufs + vrp->buf_size * vrp->last_sbuf++;
> > + ret = vrp->sbufs + vrp->sbuf_size * vrp->last_sbuf++;
> > /* or recycle a used one */
> > else
> > ret = virtqueue_get_buf(vrp->svq, &len);
> > @@ -578,7 +578,7 @@ static int rpmsg_send_offchannel_raw(struct rpmsg_device *rpdev,
> > * messaging), or to improve the buffer allocator, to support
> > * variable-length buffer sizes.
> > */
> > - if (len > vrp->buf_size - sizeof(struct rpmsg_hdr)) {
> > + if (len > vrp->sbuf_size - sizeof(struct rpmsg_hdr)) {
> > dev_err(dev, "message is too big (%d)\n", len);
> > return -EMSGSIZE;
> > }
> > @@ -718,7 +718,7 @@ static int rpmsg_recv_single(struct virtproc_info *vrp, struct device *dev,
> > * We currently use fixed-sized buffers, so trivially sanitize
> > * the reported payload length.
> > */
> > - if (len > vrp->buf_size ||
> > + if (len > vrp->rbuf_size ||
> > msg->len > (len - sizeof(struct rpmsg_hdr))) {
> > dev_warn(dev, "inbound msg too big: (%d, %d)\n", len, msg->len);
> > return -EINVAL;
> > @@ -751,7 +751,7 @@ static int rpmsg_recv_single(struct virtproc_info *vrp, struct device *dev,
> > dev_warn(dev, "msg received with no recipient\n");
> >
> > /* publish the real size of the buffer */
> > - rpmsg_sg_init(&sg, msg, vrp->buf_size);
> > + rpmsg_sg_init(&sg, msg, vrp->rbuf_size);
> >
> > /* add the buffer back to the remote processor's virtqueue */
> > err = virtqueue_add_inbuf(vrp->rvq, &sg, 1, msg, GFP_KERNEL);
> > @@ -907,11 +907,24 @@ static int rpmsg_probe(struct virtio_device *vdev)
> > else
> > vrp->num_sbufs = MAX_RPMSG_NUM_BUFS;
> >
> > - vrp->buf_size = MAX_RPMSG_BUF_SIZE;
> > + /* try to get buffer size from config space */
> > + if (virtio_has_feature(vdev, VIRTIO_RPMSG_F_BUFSZ)) {
> > + /* note: virtio_rpmsg_config is defined from remote view */
> > + virtio_cread(vdev, struct virtio_rpmsg_config,
> > + txbuf_size, &vrp->rbuf_size);
> > + virtio_cread(vdev, struct virtio_rpmsg_config,
> > + rxbuf_size, &vrp->sbuf_size);
> > + }
> > +
> > + /* use the default if resource table doesn't provide one */
> > + if (!vrp->rbuf_size)
> > + vrp->rbuf_size = MAX_RPMSG_BUF_SIZE;
> > + if (!vrp->sbuf_size)
> > + vrp->sbuf_size = MAX_RPMSG_BUF_SIZE;
> >
> > /* allocate coherent memory for the buffers */
> > vrp->rbufs = dma_alloc_coherent(vdev->dev.parent->parent,
> > - vrp->num_rbufs * vrp->buf_size,
> > + vrp->num_rbufs * vrp->rbuf_size,
> > &vrp->rbufs_dma, GFP_KERNEL);
> > if (!vrp->rbufs) {
> > err = -ENOMEM;
> > @@ -922,7 +935,7 @@ static int rpmsg_probe(struct virtio_device *vdev)
> > vrp->rbufs, &vrp->rbufs_dma);
> >
> > vrp->sbufs = dma_alloc_coherent(vdev->dev.parent->parent,
> > - vrp->num_sbufs * vrp->buf_size,
> > + vrp->num_sbufs * vrp->sbuf_size,
> > &vrp->sbufs_dma, GFP_KERNEL);
> > if (!vrp->sbufs) {
> > err = -ENOMEM;
> > @@ -935,9 +948,9 @@ static int rpmsg_probe(struct virtio_device *vdev)
> > /* set up the receive buffers */
> > for (i = 0; i < vrp->num_rbufs; i++) {
> > struct scatterlist sg;
> > - void *cpu_addr = vrp->rbufs + i * vrp->buf_size;
> > + void *cpu_addr = vrp->rbufs + i * vrp->rbuf_size;
> >
> > - rpmsg_sg_init(&sg, cpu_addr, vrp->buf_size);
> > + rpmsg_sg_init(&sg, cpu_addr, vrp->rbuf_size);
> >
> > err = virtqueue_add_inbuf(vrp->rvq, &sg, 1, cpu_addr,
> > GFP_KERNEL);
> > @@ -984,11 +997,11 @@ static int rpmsg_probe(struct virtio_device *vdev)
> >
> > free_sbufs:
> > dma_free_coherent(vdev->dev.parent->parent,
> > - vrp->num_sbufs * vrp->buf_size,
> > + vrp->num_sbufs * vrp->sbuf_size,
> > vrp->sbufs, vrp->sbufs_dma);
> > free_rbufs:
> > dma_free_coherent(vdev->dev.parent->parent,
> > - vrp->num_rbufs * vrp->buf_size,
> > + vrp->num_rbufs * vrp->rbuf_size,
> > vrp->rbufs, vrp->rbufs_dma);
> > vqs_del:
> > vdev->config->del_vqs(vrp->vdev);
> > @@ -1023,10 +1036,10 @@ static void rpmsg_remove(struct virtio_device *vdev)
> > vdev->config->del_vqs(vrp->vdev);
> >
> > dma_free_coherent(vdev->dev.parent->parent,
> > - vrp->num_sbufs * vrp->buf_size,
> > + vrp->num_sbufs * vrp->sbuf_size,
> > vrp->sbufs, vrp->sbufs_dma);
> > dma_free_coherent(vdev->dev.parent->parent,
> > - vrp->num_rbufs * vrp->buf_size,
> > + vrp->num_rbufs * vrp->rbuf_size,
> > vrp->rbufs, vrp->rbufs_dma);
> >
> > kfree(vrp);
> > @@ -1039,6 +1052,7 @@ static struct virtio_device_id id_table[] = {
> >
> > static unsigned int features[] = {
> > VIRTIO_RPMSG_F_NS,
> > + VIRTIO_RPMSG_F_BUFSZ,
> > };
> >
> > static struct virtio_driver virtio_ipc_driver = {
> > diff --git a/include/uapi/linux/virtio_rpmsg.h b/include/uapi/linux/virtio_rpmsg.h
> > new file mode 100644
> > index 0000000..24fa0dd
> > --- /dev/null
> > +++ b/include/uapi/linux/virtio_rpmsg.h
> > @@ -0,0 +1,24 @@
> > +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> > +/*
> > + * Copyright (C) Pinecone Inc. 2019
> > + * Copyright (C) Xiang Xiao <xiaoxiang@xxxxxxxxxxxx>
> > + */
> > +
> > +#ifndef _UAPI_LINUX_VIRTIO_RPMSG_H
> > +#define _UAPI_LINUX_VIRTIO_RPMSG_H
> > +
> > +#include <linux/types.h>
> > +
> > +/* The feature bitmap for virtio rpmsg */
> > +#define VIRTIO_RPMSG_F_NS 0 /* RP supports name service notifications */
> > +#define VIRTIO_RPMSG_F_BUFSZ 2 /* RP get buffer size from config space */
> > +
> > +struct virtio_rpmsg_config {
> > + /* The tx/rx individual buffer size(if VIRTIO_RPMSG_F_BUFSZ) */
> > + __u32 txbuf_size;
> > + __u32 rxbuf_size;
> > + __u32 reserved[14]; /* Reserve for the future use */
> > + /* Put the customize config here */
> > +} __attribute__((packed));
> > +
> > +#endif /* _UAPI_LINUX_VIRTIO_RPMSG_H */
> >

Next message: Steven Rostedt: "Re: [PATCH 02/25] tracing: Improve "if" macro code generation"
Previous message: Christophe Leroy: "[PATCH] powerpc/32s: fix flush_hash_pages() on SMP"
In reply to: Arnaud Pouliquen: "Re: [PATCH 3/3] rpmsg: virtio_rpmsg_bus: get buffer size from config space"
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