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

[Arnaud Pouliquen]

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...

Main differences (except interesting RX/TX size split) seems that you
- don't use the virtio_config_ops->get
- define a new feature VIRTIO_RPMSG_F_NS.

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 */
>