diff options
Diffstat (limited to 'drivers/char/virtio_console.c')
| -rw-r--r-- | drivers/char/virtio_console.c | 210 |
1 files changed, 189 insertions, 21 deletions
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index cdf2f5451c7..8ab9c3d4bf1 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -24,6 +24,8 @@ #include <linux/err.h> #include <linux/freezer.h> #include <linux/fs.h> +#include <linux/splice.h> +#include <linux/pagemap.h> #include <linux/init.h> #include <linux/list.h> #include <linux/poll.h> @@ -474,26 +476,53 @@ static ssize_t send_control_msg(struct port *port, unsigned int event, return 0; } +struct buffer_token { + union { + void *buf; + struct scatterlist *sg; + } u; + /* If sgpages == 0 then buf is used, else sg is used */ + unsigned int sgpages; +}; + +static void reclaim_sg_pages(struct scatterlist *sg, unsigned int nrpages) +{ + int i; + struct page *page; + + for (i = 0; i < nrpages; i++) { + page = sg_page(&sg[i]); + if (!page) + break; + put_page(page); + } + kfree(sg); +} + /* Callers must take the port->outvq_lock */ static void reclaim_consumed_buffers(struct port *port) { - void *buf; + struct buffer_token *tok; unsigned int len; if (!port->portdev) { /* Device has been unplugged. vqs are already gone. */ return; } - while ((buf = virtqueue_get_buf(port->out_vq, &len))) { - kfree(buf); + while ((tok = virtqueue_get_buf(port->out_vq, &len))) { + if (tok->sgpages) + reclaim_sg_pages(tok->u.sg, tok->sgpages); + else + kfree(tok->u.buf); + kfree(tok); port->outvq_full = false; } } -static ssize_t send_buf(struct port *port, void *in_buf, size_t in_count, - bool nonblock) +static ssize_t __send_to_port(struct port *port, struct scatterlist *sg, + int nents, size_t in_count, + struct buffer_token *tok, bool nonblock) { - struct scatterlist sg[1]; struct virtqueue *out_vq; ssize_t ret; unsigned long flags; @@ -505,8 +534,7 @@ static ssize_t send_buf(struct port *port, void *in_buf, size_t in_count, reclaim_consumed_buffers(port); - sg_init_one(sg, in_buf, in_count); - ret = virtqueue_add_buf(out_vq, sg, 1, 0, in_buf, GFP_ATOMIC); + ret = virtqueue_add_buf(out_vq, sg, nents, 0, tok, GFP_ATOMIC); /* Tell Host to go! */ virtqueue_kick(out_vq); @@ -544,6 +572,37 @@ done: return in_count; } +static ssize_t send_buf(struct port *port, void *in_buf, size_t in_count, + bool nonblock) +{ + struct scatterlist sg[1]; + struct buffer_token *tok; + + tok = kmalloc(sizeof(*tok), GFP_ATOMIC); + if (!tok) + return -ENOMEM; + tok->sgpages = 0; + tok->u.buf = in_buf; + + sg_init_one(sg, in_buf, in_count); + + return __send_to_port(port, sg, 1, in_count, tok, nonblock); +} + +static ssize_t send_pages(struct port *port, struct scatterlist *sg, int nents, + size_t in_count, bool nonblock) +{ + struct buffer_token *tok; + + tok = kmalloc(sizeof(*tok), GFP_ATOMIC); + if (!tok) + return -ENOMEM; + tok->sgpages = nents; + tok->u.sg = sg; + + return __send_to_port(port, sg, nents, in_count, tok, nonblock); +} + /* * Give out the data that's requested from the buffer that we have * queued up. @@ -665,6 +724,26 @@ static ssize_t port_fops_read(struct file *filp, char __user *ubuf, return fill_readbuf(port, ubuf, count, true); } +static int wait_port_writable(struct port *port, bool nonblock) +{ + int ret; + + if (will_write_block(port)) { + if (nonblock) + return -EAGAIN; + + ret = wait_event_freezable(port->waitqueue, + !will_write_block(port)); + if (ret < 0) + return ret; + } + /* Port got hot-unplugged. */ + if (!port->guest_connected) + return -ENODEV; + + return 0; +} + static ssize_t port_fops_write(struct file *filp, const char __user *ubuf, size_t count, loff_t *offp) { @@ -681,18 +760,9 @@ static ssize_t port_fops_write(struct file *filp, const char __user *ubuf, nonblock = filp->f_flags & O_NONBLOCK; - if (will_write_block(port)) { - if (nonblock) - return -EAGAIN; - - ret = wait_event_freezable(port->waitqueue, - !will_write_block(port)); - if (ret < 0) - return ret; - } - /* Port got hot-unplugged. */ - if (!port->guest_connected) - return -ENODEV; + ret = wait_port_writable(port, nonblock); + if (ret < 0) + return ret; count = min((size_t)(32 * 1024), count); @@ -725,6 +795,93 @@ out: return ret; } +struct sg_list { + unsigned int n; + unsigned int size; + size_t len; + struct scatterlist *sg; +}; + +static int pipe_to_sg(struct pipe_inode_info *pipe, struct pipe_buffer *buf, + struct splice_desc *sd) +{ + struct sg_list *sgl = sd->u.data; + unsigned int offset, len; + + if (sgl->n == sgl->size) + return 0; + + /* Try lock this page */ + if (buf->ops->steal(pipe, buf) == 0) { + /* Get reference and unlock page for moving */ + get_page(buf->page); + unlock_page(buf->page); + + len = min(buf->len, sd->len); + sg_set_page(&(sgl->sg[sgl->n]), buf->page, len, buf->offset); + } else { + /* Failback to copying a page */ + struct page *page = alloc_page(GFP_KERNEL); + char *src = buf->ops->map(pipe, buf, 1); + char *dst; + + if (!page) + return -ENOMEM; + dst = kmap(page); + + offset = sd->pos & ~PAGE_MASK; + + len = sd->len; + if (len + offset > PAGE_SIZE) + len = PAGE_SIZE - offset; + + memcpy(dst + offset, src + buf->offset, len); + + kunmap(page); + buf->ops->unmap(pipe, buf, src); + + sg_set_page(&(sgl->sg[sgl->n]), page, len, offset); + } + sgl->n++; + sgl->len += len; + + return len; +} + +/* Faster zero-copy write by splicing */ +static ssize_t port_fops_splice_write(struct pipe_inode_info *pipe, + struct file *filp, loff_t *ppos, + size_t len, unsigned int flags) +{ + struct port *port = filp->private_data; + struct sg_list sgl; + ssize_t ret; + struct splice_desc sd = { + .total_len = len, + .flags = flags, + .pos = *ppos, + .u.data = &sgl, + }; + + ret = wait_port_writable(port, filp->f_flags & O_NONBLOCK); + if (ret < 0) + return ret; + + sgl.n = 0; + sgl.len = 0; + sgl.size = pipe->nrbufs; + sgl.sg = kmalloc(sizeof(struct scatterlist) * sgl.size, GFP_KERNEL); + if (unlikely(!sgl.sg)) + return -ENOMEM; + + sg_init_table(sgl.sg, sgl.size); + ret = __splice_from_pipe(pipe, &sd, pipe_to_sg); + if (likely(ret > 0)) + ret = send_pages(port, sgl.sg, sgl.n, sgl.len, true); + + return ret; +} + static unsigned int port_fops_poll(struct file *filp, poll_table *wait) { struct port *port; @@ -856,6 +1013,7 @@ static const struct file_operations port_fops = { .open = port_fops_open, .read = port_fops_read, .write = port_fops_write, + .splice_write = port_fops_splice_write, .poll = port_fops_poll, .release = port_fops_release, .fasync = port_fops_fasync, @@ -1941,7 +2099,17 @@ static int __init init(void) INIT_LIST_HEAD(&pdrvdata.consoles); INIT_LIST_HEAD(&pdrvdata.portdevs); - return register_virtio_driver(&virtio_console); + err = register_virtio_driver(&virtio_console); + if (err < 0) { + pr_err("Error %d registering virtio driver\n", err); + goto free; + } + return 0; +free: + if (pdrvdata.debugfs_dir) + debugfs_remove_recursive(pdrvdata.debugfs_dir); + class_destroy(pdrvdata.class); + return err; } static void __exit fini(void) |