Adding support for generic ports that will write to userspace will need some code changes.
Consolidate the write routine into send_buf() and put_chars() now just calls into the new function. Signed-off-by: Amit Shah <[email protected]> --- drivers/char/virtio_console.c | 79 +++++++++++++++++++++++++++++++--------- 1 files changed, 61 insertions(+), 18 deletions(-) diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index 5096d92..9400b96 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -107,6 +107,9 @@ struct port { */ spinlock_t inbuf_lock; + /* Buffer that's used to pass data from the guest to the host */ + struct port_buffer *outbuf; + /* The IO vqs for this port */ struct virtqueue *in_vq, *out_vq; @@ -233,6 +236,55 @@ static bool port_has_data(struct port *port) return ret; } +static ssize_t send_buf(struct port *port, const char *in_buf, size_t in_count) +{ + struct scatterlist sg[1]; + struct virtqueue *out_vq; + struct port_buffer *buf; + ssize_t ret; + unsigned int tmplen; + + out_vq = port->out_vq; + buf = port->outbuf; + + if (in_count > buf->size) + in_count = buf->size; + + /* + * Since we're not sure when the host will actually + * consume the data and tell us about it, we have to + * copy the data here in case the caller frees the + * in_buf. + */ + memcpy(buf->buf, in_buf, in_count); + + buf->len = in_count; + + sg_init_one(sg, buf->buf, buf->len); + ret = out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, buf); + + /* Tell Host to go! */ + out_vq->vq_ops->kick(out_vq); + + if (ret < 0) { + buf->len = 0; + goto fail; + } + + /* + * Wait till the host acknowledges it pushed out the data we + * sent. Also ensure we return to userspace the number of + * bytes that were successfully consumed by the host. + */ + while (!out_vq->vq_ops->get_buf(out_vq, &tmplen)) + cpu_relax(); + + buf->len = tmplen; +fail: + /* We're expected to return the amount of data we wrote */ + return buf->len; +} + /* * Give out the data that's requested from the buffer that we have * queued up. @@ -280,10 +332,7 @@ static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count) */ static int put_chars(u32 vtermno, const char *buf, int count) { - struct scatterlist sg[1]; struct port *port; - struct virtqueue *out_vq; - unsigned int len; port = find_port_by_vtermno(vtermno); if (!port) @@ -292,20 +341,7 @@ static int put_chars(u32 vtermno, const char *buf, int count) if (unlikely(early_put_chars)) return early_put_chars(vtermno, buf, count); - out_vq = port->out_vq; - /* This is a convenient routine to initialize a single-elem sg list */ - sg_init_one(sg, buf, count); - - /* This shouldn't fail: if it does, we lose chars. */ - if (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, port) >= 0) { - /* Tell Host to go! */ - out_vq->vq_ops->kick(out_vq); - while (!out_vq->vq_ops->get_buf(out_vq, &len)) - cpu_relax(); - } - - /* We're expected to return the amount of data we wrote: all of it. */ - return count; + return send_buf(port, buf, count); } /* @@ -475,16 +511,23 @@ static int __devinit add_port(struct ports_device *portdev) err = -ENOMEM; goto free_port; } + port->outbuf = alloc_buf(PAGE_SIZE); + if (!port->outbuf) { + err = -ENOMEM; + goto free_inbuf; + } /* Register the input buffer the first time. */ add_inbuf(port->in_vq, inbuf); err = init_port_console(port); if (err) - goto free_inbuf; + goto free_outbuf; return 0; +free_outbuf: + free_buf(port->outbuf); free_inbuf: free_buf(inbuf); free_port: -- 1.6.2.5 _______________________________________________ Virtualization mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/virtualization
