Re: virtio-serial: An interface for host-guest communication

Message ID	20090814081518.GA7418@amit-x200.redhat.com
State	Superseded
Headers	show Return-Path: <qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org> Date: Fri, 14 Aug 2009 13:45:18 +0530 From: Amit Shah <amit.shah@redhat.com> To: Anthony Liguori <anthony@codemonkey.ws> Subject: Re: [Qemu-devel] Re: virtio-serial: An interface for host-guest communication Message-ID: <20090814081518.GA7418@amit-x200.redhat.com> References: <20090806173740.GA1178@shareable.org> <20090807063800.GA16769@amit-x200.redhat.com> <4A7C36D3.3040305@codemonkey.ws> <20090810065508.GA4499@amit-x200.redhat.com> <4A7FECCA.8080804@redhat.com> <4A801A7B.1020208@codemonkey.ws> <4A80287C.7050400@redhat.com> <4A802CA7.9020701@codemonkey.ws> <4A803E07.7080407@redhat.com> <4A8051F3.7040400@codemonkey.ws> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4A8051F3.7040400@codemonkey.ws> User-Agent: Mutt/1.5.19 (2009-01-05) Cc: Rusty Russell <rusty@rustcorp.com.au>, virtualization@lists.linux-foundation.org, Gerd Hoffmann <kraxel@redhat.com>, kvm@vger.kernel.org, qemu-devel@nongnu.org Precedence: list Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org

diff --git a/drivers/char/Makefile b/drivers/char/Makefile index 5e1915b..ab9c914 100644 --- a/drivers/char/Makefile +++ b/drivers/char/Makefile @@ -53,7 +53,6 @@ obj-$(CONFIG_HVC_IRQ) += hvc_irq.o obj-$(CONFIG_HVC_XEN) += hvc_xen.o obj-$(CONFIG_HVC_IUCV) += hvc_iucv.o obj-$(CONFIG_HVC_UDBG) += hvc_udbg.o -obj-$(CONFIG_VIRTIO_CONSOLE) += virtio_console.o obj-$(CONFIG_VIRTIO_SERIAL) += virtio_serial.o obj-$(CONFIG_RAW_DRIVER) += raw.o obj-$(CONFIG_SGI_SNSC) += snsc.o snsc_event.o diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index c74dacf..f82c036 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -43,39 +43,6 @@ static struct virtio_device *vdev; static unsigned int in_len; static char *in, *inbuf; -/* The operations for our console. */ -static struct hv_ops virtio_cons; - -/* The hvc device */ -static struct hvc_struct *hvc; - -/*D:310 The put_chars() callback is pretty straightforward. - * - * We turn the characters into a scatter-gather list, add it to the output - * queue and then kick the Host. Then we sit here waiting for it to finish: - * inefficient in theory, but in practice implementations will do it - * immediately (lguest's Launcher does). */ -static int put_chars(u32 vtermno, const char *buf, int count) -{ - struct scatterlist sg[1]; - unsigned int len; - - /* This is a convenient routine to initialize a single-elem sg list */ - sg_init_one(sg, buf, count); - - /* add_buf wants a token to identify this buffer: we hand it any - * non-NULL pointer, since there's only ever one buffer. */ - if (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, (void *)1) == 0) { - /* Tell Host to go! */ - out_vq->vq_ops->kick(out_vq); - /* Chill out until it's done with the buffer. */ - 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; -} /* Create a scatter-gather list representing our input buffer and put it in the * queue. */ @@ -90,94 +57,7 @@ static void add_inbuf(void) in_vq->vq_ops->kick(in_vq); } -/*D:350 get_chars() is the callback from the hvc_console infrastructure when - * an interrupt is received. - * - * Most of the code deals with the fact that the hvc_console() infrastructure - * only asks us for 16 bytes at a time. We keep in_offset and in_used fields - * for partially-filled buffers. */ -static int get_chars(u32 vtermno, char *buf, int count) -{ - /* If we don't have an input queue yet, we can't get input. */ - BUG_ON(!in_vq); - - /* No buffer? Try to get one. */ - if (!in_len) { - in = in_vq->vq_ops->get_buf(in_vq, &in_len); - if (!in) - return 0; - } - - /* You want more than we have to give? Well, try wanting less! */ - if (in_len < count) - count = in_len; - - /* Copy across to their buffer and increment offset. */ - memcpy(buf, in, count); - in += count; - in_len -= count; - /* Finished? Re-register buffer so Host will use it again. */ - if (in_len == 0) - add_inbuf(); - - return count; -} -/*:*/ - -/*D:320 Console drivers are initialized very early so boot messages can go out, - * so we do things slightly differently from the generic virtio initialization - * of the net and block drivers. - * - * At this stage, the console is output-only. It's too early to set up a - * virtqueue, so we let the drivers do some boutique early-output thing. */ -int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int)) -{ - virtio_cons.put_chars = put_chars; - return hvc_instantiate(0, 0, &virtio_cons); -} - -/* - * virtio console configuration. This supports: - * - console resize - */ -static void virtcons_apply_config(struct virtio_device *dev) -{ - struct winsize ws; - - if (virtio_has_feature(dev, VIRTIO_CONSOLE_F_SIZE)) { - dev->config->get(dev, - offsetof(struct virtio_console_config, cols), - &ws.ws_col, sizeof(u16)); - dev->config->get(dev, - offsetof(struct virtio_console_config, rows), - &ws.ws_row, sizeof(u16)); - hvc_resize(hvc, ws); - } -} - -/* - * we support only one console, the hvc struct is a global var - * We set the configuration at this point, since we now have a tty - */ -static int notifier_add_vio(struct hvc_struct *hp, int data) -{ - hp->irq_requested = 1; - virtcons_apply_config(vdev); - - return 0; -} - -static void notifier_del_vio(struct hvc_struct *hp, int data) -{ - hp->irq_requested = 0; -} - -static void hvc_handle_input(struct virtqueue *vq) -{ - if (hvc_poll(hvc)) - hvc_kick(); -} /*D:370 Once we're further in boot, we get probed like any other virtio device. * At this stage we set up the output virtqueue. @@ -212,27 +92,7 @@ static int __devinit virtcons_probe(struct virtio_device *dev) in_vq = vqs[0]; out_vq = vqs[1]; - /* Start using the new console output. */ - virtio_cons.get_chars = get_chars; - virtio_cons.put_chars = put_chars; - virtio_cons.notifier_add = notifier_add_vio; - virtio_cons.notifier_del = notifier_del_vio; - virtio_cons.notifier_hangup = notifier_del_vio; - /* The first argument of hvc_alloc() is the virtual console number, so - * we use zero. The second argument is the parameter for the - * notification mechanism (like irq number). We currently leave this - * as zero, virtqueues have implicit notifications. - * - * The third argument is a "struct hv_ops" containing the put_chars() - * get_chars(), notifier_add() and notifier_del() pointers. - * The final argument is the output buffer size: we can do any size, - * so we put PAGE_SIZE here. */ - hvc = hvc_alloc(0, 0, &virtio_cons, PAGE_SIZE); - if (IS_ERR(hvc)) { - err = PTR_ERR(hvc); - goto free_vqs; - } /* Register the input buffer the first time. */ add_inbuf(); diff --git a/drivers/char/virtio_serial.c b/drivers/char/virtio_serial.c index ef2d730..ff6ad06 100644 --- a/drivers/char/virtio_serial.c +++ b/drivers/char/virtio_serial.c @@ -37,6 +37,7 @@ #include <linux/virtio.h> #include <linux/virtio_serial.h> #include <linux/workqueue.h> +#include "hvc_console.h" struct virtio_serial_struct { struct work_struct rx_work; @@ -131,27 +132,13 @@ static int send_control_event(struct virtio_serial_control *sercontrol) return ret; } -static ssize_t virtserial_read(struct file *filp, char __user *ubuf, - size_t count, loff_t *offp) +static ssize_t fill_readbuf(struct virtio_serial_port *port, char *out_buf, + size_t count, bool to_user) { - struct virtio_serial_port *port; struct virtio_serial_port_buffer *buf, *buf2; - ssize_t ubuf_offset, ret; - - port = filp->private_data; - - ret = 0; - if (list_empty(&port->readbuf_head)) { - if (filp->f_flags & O_NONBLOCK) - return -EAGAIN; + ssize_t out_offset, ret; - ret = wait_event_interruptible(port->waitqueue, - !list_empty(&port->readbuf_head)); - } - if (ret < 0) - return ret; - - ubuf_offset = 0; + out_offset = 0; list_for_each_entry_safe(buf, buf2, &port->readbuf_head, next) { size_t copy_size; @@ -159,16 +146,24 @@ static ssize_t virtserial_read(struct file *filp, char __user *ubuf, if (copy_size > buf->len - buf->offset) copy_size = buf->len - buf->offset; - ret = copy_to_user(ubuf + ubuf_offset, buf->buf + buf->offset, - copy_size); + if (to_user) { + ret = copy_to_user(out_buf + out_offset, + buf->buf + buf->offset, + copy_size); + /* FIXME: Deal with ret != 0 */ + } else { + memcpy(out_buf + out_offset, + buf->buf + buf->offset, + copy_size); + ret = 0; /* Emulate copy_to_user behaviour */ + } - /* FIXME: Deal with ret != 0 */ /* Return the number of bytes actually copied */ ret = copy_size - ret; buf->offset += ret; - ubuf_offset += ret; + out_offset += ret; count -= ret; - ret = ubuf_offset; + ret = out_offset; if (buf->len - buf->offset == 0) { list_del(&buf->next); @@ -178,6 +173,30 @@ static ssize_t virtserial_read(struct file *filp, char __user *ubuf, if (!count) break; } + return out_offset; +} + +static ssize_t virtserial_read(struct file *filp, char __user *ubuf, + size_t count, loff_t *offp) +{ + struct virtio_serial_port *port; + ssize_t ret; + + port = filp->private_data; + + ret = 0; + if (list_empty(&port->readbuf_head)) { + if (filp->f_flags & O_NONBLOCK) + return -EAGAIN; + + ret = wait_event_interruptible(port->waitqueue, + !list_empty(&port->readbuf_head)); + } + if (ret < 0) + return ret; + + ret = fill_readbuf(port, ubuf, count, 1); + return ret; } @@ -196,21 +215,19 @@ struct vbuf { unsigned int nent; }; -static ssize_t virtserial_write(struct file *filp, const char __user *ubuf, - size_t count, loff_t *offp) +static ssize_t send_writebuf(struct virtio_serial_port *port, + const char *in_buf, size_t count, bool from_user) { struct virtqueue *out_vq; - struct virtio_serial_port *port; struct virtio_serial_id id; struct vbuf *vbuf; - size_t offset, size; + size_t in_offset, copy_size; ssize_t ret; unsigned int i, id_len; if (!count) return 0; - port = filp->private_data; id.id = get_id_from_port(port); out_vq = virtserial.out_vq; @@ -234,10 +251,10 @@ static ssize_t virtserial_write(struct file *filp, const char __user *ubuf, sg_init_table(vbuf->sg, vbuf->nent); i = 0; /* vbuf->bufs[i] */ - offset = 0; /* offset in the user buffer */ - while (count - offset) { - size = min(count - offset + id_len, PAGE_SIZE); - vbuf->bufs[i] = kzalloc(size, GFP_KERNEL); + in_offset = 0; /* offset in the source buffer */ + while (count - in_offset) { + copy_size = min(count - in_offset + id_len, PAGE_SIZE); + vbuf->bufs[i] = kzalloc(copy_size, GFP_KERNEL); if (!vbuf->bufs[i]) { ret = -ENOMEM; if (!i) @@ -246,12 +263,25 @@ static ssize_t virtserial_write(struct file *filp, const char __user *ubuf, } if (id_len) { memcpy(vbuf->bufs[i], &id, id_len); - size -= id_len; + copy_size -= id_len; } - ret = copy_from_user(vbuf->bufs[i] + id_len, ubuf + offset, size); - offset += size - ret; + if (from_user) + ret = copy_from_user(vbuf->bufs[i] + id_len, + in_buf + in_offset, copy_size); + else { + /* 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 string + */ + memcpy(vbuf->bufs[i] + id_len, + in_buf + in_offset, copy_size); + ret = 0; /* Emulate copy_from_user */ + } + in_offset += copy_size - ret; - sg_set_buf(&vbuf->sg[i], vbuf->bufs[i], size - ret + id_len); + sg_set_buf(&vbuf->sg[i], vbuf->bufs[i], + copy_size - ret + id_len); id_len = 0; /* Pass the port id only in the first buffer */ i++; } @@ -263,7 +293,7 @@ static ssize_t virtserial_write(struct file *filp, const char __user *ubuf, out_vq->vq_ops->kick(out_vq); /* We're expected to return the amount of data we wrote */ - return offset; + return in_offset; free_buffers: while (--i >= 0) kfree(vbuf->bufs[i]); @@ -276,6 +306,16 @@ free_vbuf: return ret; } +static ssize_t virtserial_write(struct file *filp, const char __user *ubuf, + size_t count, loff_t *offp) +{ + struct virtio_serial_port *port; + + port = filp->private_data; + + return send_writebuf(port, ubuf, count, 1); +} + static int virtserial_release(struct inode *inode, struct file *filp) { struct virtio_serial_control *sercontrol; @@ -343,6 +383,104 @@ static const struct file_operations virtserial_fops = { .release = virtserial_release, }; +/* Some routines for supporting virtio console */ + +/* The operations for our console. */ +static struct hv_ops virtio_cons; + +/* The hvc device */ +static struct hvc_struct *hvc; + +/*D:310 The console_put_chars() callback is pretty straightforward. + * + * We turn the characters into a scatter-gather list, add it to the output + * queue and then kick the Host. Then we sit here waiting for it to finish: + * inefficient in theory, but in practice implementations will do it + * immediately (lguest's Launcher does). */ +static int console_put_chars(u32 vtermno, const char *buf, int count) +{ + struct virtio_serial_port *port; + + port = get_port_from_id(VIRTIO_SERIAL_CONSOLE_PORT); + if (!port) + return 0; + + return send_writebuf(port, buf, count, 0); +} + +/*D:350 console_get_chars() is the callback from the hvc_console + * infrastructure when an interrupt is received. + * + * Most of the code deals with the fact that the hvc_console() infrastructure + * only asks us for 16 bytes at a time. We keep in_offset and in_used fields + * for partially-filled buffers. */ +static int console_get_chars(u32 vtermno, char *out_buf, int count) +{ + struct virtio_serial_port *port; + + /* If we don't have an input queue yet, we can't get input. */ + BUG_ON(!virtserial.in_vq); + + port = get_port_from_id(VIRTIO_SERIAL_CONSOLE_PORT); + if (!port) + return 0; + + if (list_empty(&port->readbuf_head)) + return 0; + + return fill_readbuf(port, out_buf, count, 0); +} +/*:*/ + +/*D:320 Console drivers are initialized very early so boot messages can go out, + * so we do things slightly differently from the generic virtio initialization + * of the net and block drivers. + * + * At this stage, the console is output-only. It's too early to set up a + * virtqueue, so we let the drivers do some boutique early-output thing. */ +int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int)) +{ + virtio_cons.put_chars = put_chars; + return hvc_instantiate(0, 0, &virtio_cons); +} + +/* + * virtio console configuration. This supports: + * - console resize + */ +static void virtcons_apply_config(struct virtio_device *dev) +{ + struct winsize ws; + + if (virtio_has_feature(dev, VIRTIO_CONSOLE_F_SIZE)) { + dev->config->get(dev, + offsetof(struct virtio_serial_config, cols), + &ws.ws_col, sizeof(u16)); + dev->config->get(dev, + offsetof(struct virtio_serial_config, rows), + &ws.ws_row, sizeof(u16)); + hvc_resize(hvc, ws); + } +} + +/* + * we support only one console, the hvc struct is a global var + * We set the configuration at this point, since we now have a tty + */ +static int console_notifier_add_vio(struct hvc_struct *hp, int data) +{ + hp->irq_requested = 1; + virtcons_apply_config(virtserial.vdev); + + return 0; +} + +static void console_notifier_del_vio(struct hvc_struct *hp, int data) +{ + hp->irq_requested = 0; +} + + static void virtio_serial_queue_work_handler(struct work_struct *work) { struct scatterlist sg[1]; @@ -410,6 +548,10 @@ static void virtio_serial_rx_work_handler(struct work_struct *work) wake_up_interruptible(&port->waitqueue); } + + if (get_id_from_port(port) == VIRTIO_SERIAL_CONSOLE_PORT && hvc_poll(hvc)) + hvc_kick(); + /* Allocate buffers for all the ones that got used up */ schedule_work(&virtserial.queue_work); } @@ -555,6 +697,33 @@ static int virtserial_add_port(u32 port_nr) list_add_tail(&port->next, &virtserial.port_head); + if (port_nr == VIRTIO_SERIAL_CONSOLE_PORT) { + /* Start using the new console output. */ + virtio_cons.get_chars = console_get_chars; + virtio_cons.put_chars = console_put_chars; + virtio_cons.notifier_add = console_notifier_add_vio; + virtio_cons.notifier_del = console_notifier_del_vio; + virtio_cons.notifier_hangup = console_notifier_del_vio; + + /* The first argument of hvc_alloc() is the virtual + * console number, so we use zero. The second + * argument is the parameter for the notification + * mechanism (like irq number). We currently leave + * this as zero, virtqueues have implicit + * notifications. + * + * The third argument is a "struct hv_ops" containing + * the put_chars() get_chars(), notifier_add() and + * notifier_del() pointers. The final argument is the + * output buffer size: we can do any size, so we put + * PAGE_SIZE here. */ + hvc = hvc_alloc(0, 0, &virtio_cons, PAGE_SIZE); + if (IS_ERR(hvc)) { + ret = PTR_ERR(hvc); + goto free_cdev; + } + } + pr_info("virtio-serial port found at id %u\n", port_nr); return 0; @@ -721,9 +890,13 @@ static struct virtio_device_id id_table[] = { { 0 }, }; +static unsigned int features[] = { + VIRTIO_CONSOLE_F_SIZE, +}; + static struct virtio_driver virtio_serial = { - // .feature_table = virtserial_features, - // .feature_table_size = ARRAY_SIZE(virtserial_features), + .feature_table = features, + .feature_table_size = ARRAY_SIZE(features), .driver.name = KBUILD_MODNAME, .driver.owner = THIS_MODULE, .id_table = id_table, diff --git a/include/linux/virtio_serial.h b/include/linux/virtio_serial.h index 26ccd83..1c9f853 100644 --- a/include/linux/virtio_serial.h +++ b/include/linux/virtio_serial.h @@ -10,7 +10,16 @@ #define VIRTIO_SERIAL_BAD_ID (~(u32)0) +/* Feature bits */ +#define VIRTIO_CONSOLE_F_SIZE 0 /* Does host provide console size? */ + struct virtio_serial_config { + /* first two values come from virtio_console */ + /* colums of the screens */ + __u16 cols; + /* rows of the screens */ + __u16 rows; + __u32 max_nr_ports; __u32 nr_active_ports; __u32 ports_map[0 /* (max_nr_ports + 31) / 32 */]; @@ -22,6 +31,9 @@ struct virtio_serial_control { __u16 value; }; +/* Predefined ports */ +#define VIRTIO_SERIAL_CONSOLE_PORT 2 + /* Some events for the control channel */ /* Guest -> Host range 1..256 */ #define VIRTIO_SERIAL_GUEST_PORT_OPEN 1 @@ -31,7 +43,7 @@ struct virtio_serial_control { #ifdef __KERNEL__ -/* Guest kernel - Guest userspace interface */ +int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int)); #endif /* __KERNEL__ */ #endif /* _LINUX_VIRTIO_SERIAL_H */

Re: virtio-serial: An interface for host-guest communication

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