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[103.229.16.4]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-29b5b26fff4sm84712425ad.68.2025.11.22.04.05.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 22 Nov 2025 04:05:17 -0800 (PST) Message-ID: <11280877-95f0-4361-9112-23bb17372e91@oss.qualcomm.com> Date: Sat, 22 Nov 2025 20:05:12 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 2/2] rpmsg: virtio_rpmsg_bus: get buffer size from config space To: Tanmay Shah , andersson@kernel.org, mathieu.poirier@linaro.org, mst@redhat.com, jasowang@redhat.com, xuanzhuo@linux.alibaba.com, eperezma@redhat.com Cc: linux-kernel@vger.kernel.org, linux-remoteproc@vger.kernel.org, virtualization@lists.linux.dev, xiaoxiang@xiaomi.com, Xiang Xiao , zhongqiu.han@oss.qualcomm.com, arnaud.pouliquen@foss.st.com References: <20251114184640.3020427-1-tanmay.shah@amd.com> <20251114184640.3020427-3-tanmay.shah@amd.com> Content-Language: en-US From: Zhongqiu Han In-Reply-To: <20251114184640.3020427-3-tanmay.shah@amd.com> Content-Type: text/plain; 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> 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 bufs_dma; > struct mutex tx_lock; > @@ -70,9 +73,6 @@ struct virtproc_info { > atomic_t sleepers; > }; > > -/* 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 > @@ -130,7 +130,7 @@ struct virtio_rpmsg_channel { > * processor. > */ > #define MAX_RPMSG_NUM_BUFS (256) > -#define MAX_RPMSG_BUF_SIZE (512) > +#define DEFAULT_RPMSG_BUF_SIZE (512) > > /* > * Local addresses are dynamically allocated on-demand. > @@ -443,7 +443,7 @@ 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); > @@ -569,7 +569,7 @@ 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; > } > @@ -680,7 +680,7 @@ static ssize_t virtio_rpmsg_get_mtu(struct rpmsg_endpoint *ept) > struct rpmsg_device *rpdev = ept->rpdev; > struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev); > > - return vch->vrp->buf_size - sizeof(struct rpmsg_hdr); > + return vch->vrp->sbuf_size - sizeof(struct rpmsg_hdr); > } > > static int rpmsg_recv_single(struct virtproc_info *vrp, struct device *dev, > @@ -706,7 +706,7 @@ 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; > @@ -739,7 +739,7 @@ static int rpmsg_recv_single(struct virtproc_info *vrp, struct device *dev, > dev_warn_ratelimited(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); > @@ -888,9 +888,39 @@ static int rpmsg_probe(struct virtio_device *vdev) > else > vrp->num_sbufs = MAX_RPMSG_NUM_BUFS; > > - vrp->buf_size = MAX_RPMSG_BUF_SIZE; > + /* > + * If VIRTIO_RPMSG_F_BUFSZ feature is supported, then configure buf > + * size from virtio device config space from the resource table. > + * If the feature is not supported, then assign default buf size. > + */ > + 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); > + > + /* The buffers must hold rpmsg header atleast */ > + if (vrp->rbuf_size < sizeof(struct rpmsg_hdr) || > + vrp->sbuf_size < sizeof(struct rpmsg_hdr)) { Hello Tanmay, May I know if the omission of = here is to accommodate the ping/pong/ack scenarios? mtu will 0 > + dev_err(&vdev->dev, > + "vdev config: rx buf sz = %d, tx buf sz = %d\n", > + vrp->rbuf_size, vrp->sbuf_size); > + err = -EINVAL; > + goto vqs_del; > + } > + > + dev_dbg(&vdev->dev, > + "vdev config: rx buf sz = 0x%x, tx buf sz = 0x%x\n", > + vrp->rbuf_size, vrp->sbuf_size); > + } else { > + vrp->rbuf_size = DEFAULT_RPMSG_BUF_SIZE; > + vrp->sbuf_size = DEFAULT_RPMSG_BUF_SIZE; > + } > > - total_buf_space = (vrp->num_rbufs + vrp->num_sbufs) * vrp->buf_size; > + total_buf_space = (vrp->num_rbufs * vrp->rbuf_size) + > + (vrp->num_sbufs * vrp->sbuf_size); > + total_buf_space = ALIGN(total_buf_space, PAGE_SIZE); > > /* allocate coherent memory for the buffers */ > bufs_va = dma_alloc_coherent(vdev->dev.parent, > @@ -908,14 +938,14 @@ static int rpmsg_probe(struct virtio_device *vdev) > vrp->rbufs = bufs_va; > > /* and second part is dedicated for TX */ > - vrp->sbufs = bufs_va + vrp->num_rbufs * vrp->buf_size; > + vrp->sbufs = bufs_va + (vrp->num_rbufs * vrp->rbuf_size); > > /* 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); > @@ -1001,8 +1031,8 @@ static int rpmsg_remove_device(struct device *dev, void *data) > static void rpmsg_remove(struct virtio_device *vdev) > { > struct virtproc_info *vrp = vdev->priv; > - unsigned int num_bufs = vrp->num_rbufs + vrp->num_sbufs; > - size_t total_buf_space = num_bufs * vrp->buf_size; > + size_t total_buf_space = (vrp->num_rbufs * vrp->rbuf_size) + > + (vrp->num_sbufs * vrp->sbuf_size); > int ret; > > virtio_reset_device(vdev); > @@ -1015,6 +1045,7 @@ static void rpmsg_remove(struct virtio_device *vdev) > > vdev->config->del_vqs(vrp->vdev); > > + total_buf_space = ALIGN(total_buf_space, PAGE_SIZE); > dma_free_coherent(vdev->dev.parent, total_buf_space, > vrp->rbufs, vrp->bufs_dma); > > @@ -1028,6 +1059,7 @@ 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/linux/virtio_rpmsg.h b/include/linux/virtio_rpmsg.h > new file mode 100644 > index 000000000000..6406bc505383 > --- /dev/null > +++ b/include/linux/virtio_rpmsg.h > @@ -0,0 +1,24 @@ > +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ Echo Arnaud's comments. If it is intended for UAPI, please keep it in include/uapi/linux > +/* > + * Copyright (C) Pinecone Inc. 2019 > + * Copyright (C) Xiang Xiao > + */ > + > +#ifndef _LINUX_VIRTIO_RPMSG_H > +#define _LINUX_VIRTIO_RPMSG_H > + > +#include > + > +/* 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 */ May I know why skip bit 1? > + > +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 */ Should we use __virtio32 instead of __u32 to avoid endianness issues? > + /* Put the customize config here */ > +} __attribute__((packed)); > + > +#endif /* _LINUX_VIRTIO_RPMSG_H */ -- Thx and BRs, Zhongqiu Han