virtio_console: Add support for multiple ports for generic guest and host communication
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From: Amit Shah on 5 Oct 2009 10:20 On (Thu) Oct 01 2009 [12:28:30], Christian Borntraeger wrote: > > With the latest git kernel + your patch I sometmes get a completely frozen > console. In the dump there is > > <3>virtio_console virtio0: output:id 68 is not a head! > > Seems that I can reproduce it with large amounts of output (find / for example) > Without your patch everything is fine. Hey Christian, Can you try this patch? There's something funny happening with hvc still, though. It sometimes doesn't respond to input which could mean a race somewhere. When it fails, it doesn't show up a Password: prompt on the terminal (but accepts and echoes the username fine). When it does work, however, everything seems fine. It would be great if you could try this a few times on your setup. Amit diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig index 08a6f50..fc8a04e 100644 --- a/drivers/char/Kconfig +++ b/drivers/char/Kconfig @@ -679,6 +679,12 @@ config VIRTIO_CONSOLE help Virtio console for use with lguest and other hypervisors. + Also serves as a general-purpose serial device for data + transfer between the guest and host. Character devices at + /dev/vconNN will be created when corresponding ports are + found. If specified by the host, a sysfs attribute called + 'name' will be populated with a name for the port which can + be used by udev scripts to create a symlink to /dev/vconNN. config HVCS tristate "IBM Hypervisor Virtual Console Server support" diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index 0d328b5..14a68b4 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -9,10 +9,8 @@ * functions. :*/ -/*M:002 The console can be flooded: while the Guest is processing input the - * Host can send more. Buffering in the Host could alleviate this, but it is a - * difficult problem in general. :*/ /* Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation + * Copyright (C) 2009, Amit Shah, Red Hat, Inc. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by @@ -28,116 +26,520 @@ * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ + +#include <linux/cdev.h> +#include <linux/device.h> #include <linux/err.h> +#include <linux/fs.h> #include <linux/init.h> +#include <linux/poll.h> +#include <linux/sched.h> +#include <linux/spinlock.h> #include <linux/virtio.h> #include <linux/virtio_ids.h> #include <linux/virtio_console.h> +#include <linux/workqueue.h> #include "hvc_console.h" -/*D:340 These represent our input and output console queues, and the virtio - * operations for them. */ -static struct virtqueue *in_vq, *out_vq; -static struct virtio_device *vdev; +/* This struct stores data that's common to all the ports */ +struct virtio_console_struct { + /* + * Workqueue handlers where we process deferred work after an + * interrupt + */ + struct work_struct rx_work; + struct work_struct tx_work; + struct work_struct config_work; -/* This is our input buffer, and how much data is left in it. */ -static unsigned int in_len; -static char *in, *inbuf; + struct list_head port_head; + struct list_head unused_read_head; + struct list_head unused_write_head; -/* The operations for our console. */ -static struct hv_ops virtio_cons; + /* To protect the list of unused write buffers and the out_vq */ + spinlock_t write_list_lock; + + struct virtio_device *vdev; + struct class *class; + /* The input and the output queues */ + struct virtqueue *in_vq, *out_vq; + + /* The current config space is stored here */ + struct virtio_console_config config; +}; + +/* This struct holds individual buffers received for each port */ +struct virtio_console_port_buffer { + struct list_head next; + + char *buf; + + /* length of the buffer */ + size_t len; + /* offset in the buf from which to consume data */ + size_t offset; +}; + +/* This struct holds the per-port data */ +struct virtio_console_port { + /* Next port in the list, head is in the virtio_console_struct */ + struct list_head next; + + /* Pointer to the virtio_console device */ + struct virtio_console_struct *vcon; + + /* Buffer management */ + struct list_head readbuf_head; + + /* + * To protect the readbuf_head list. Has to be a spinlock + * because it can be called from interrupt context + * (cons_get_char()) + */ + spinlock_t readbuf_list_lock; + + /* A waitqueue for poll() or blocking read operations */ + wait_queue_head_t waitqueue; + + /* Each port associates with a separate char device */ + struct cdev cdev; + struct device *dev; + + /* The hvc device, if this port is associated with a console */ + struct hvc_struct *hvc; + + /* The 'name' of the port that we expose via sysfs properties */ + char *name; + + /* The 'id' to identify the port with the Host */ + u32 id; -/* The hvc device */ -static struct hvc_struct *hvc; + /* + * If this port is a console port, this number identifies the + * number that we used to register with hvc in + * hvc_instantiate() and hvc_alloc(). + */ + u32 vtermno; -/*D:310 The put_chars() callback is pretty straightforward. + /* Is the host device open */ + bool host_connected; +}; + +static struct virtio_console_struct virtconsole; + +/* + * This is used to keep track of the number of hvc consoles spawned. + * This number is given as first argument to hvc_alloc(). We could as + * well pass on the minor number of the char device but to correctly + * map an initial console spawned via hvc_instantiate to the console + * being hooked up via hvc_alloc, we need to pass the same vtermno. * - * 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) + * With this int, we just assume the first console being initialised + * was the first one that got used as the initial console. + */ +static unsigned int hvc_vtermno; + +static struct virtio_console_port *get_port_from_vtermno(u32 vtermno) { - 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(); + struct virtio_console_port *port; + + list_for_each_entry(port, &virtconsole.port_head, next) { + if (port->hvc && port->vtermno == vtermno) + return port; } + return NULL; +} + +static struct virtio_console_port *get_port_from_devt(dev_t devt) +{ + struct virtio_console_port *port; - /* We're expected to return the amount of data we wrote: all of it. */ - return count; + list_for_each_entry(port, &virtconsole.port_head, next) { + if (port->dev->devt == devt) + return port; + } + return NULL; } -/* Create a scatter-gather list representing our input buffer and put it in the - * queue. */ -static void add_inbuf(void) +static struct virtio_console_port *get_port_from_id(u32 id) { - struct scatterlist sg[1]; - sg_init_one(sg, inbuf, PAGE_SIZE); + struct virtio_console_port *port; - /* We should always be able to add one buffer to an empty queue. */ - if (in_vq->vq_ops->add_buf(in_vq, sg, 0, 1, inbuf) < 0) - BUG(); - in_vq->vq_ops->kick(in_vq); + list_for_each_entry(port, &virtconsole.port_head, next) { + if (port->id == id) + return port; + } + return NULL; } -/*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) +static int get_id_from_port(struct virtio_console_port *port) { - /* If we don't have an input queue yet, we can't get input. */ - BUG_ON(!in_vq); + return port->id; +} - /* No buffer? Try to get one. */ - if (!in_len) { - in = in_vq->vq_ops->get_buf(in_vq, &in_len); - if (!in) +static bool is_console_port(struct virtio_console_port *port) +{ + if (port->hvc) + return true; + return false; +} + +static inline bool use_multiport(struct virtio_console_struct *vcon) +{ + /* + * This condition can be true when put_chars is called from + * early_init + */ + if (!vcon->vdev) + return 0; + return vcon->vdev->features[0] & (1 << VIRTIO_CONSOLE_F_MULTIPORT); +} + +static inline bool is_internal(u32 flags) +{ + return flags & VIRTIO_CONSOLE_ID_INTERNAL; +} + +/* + * Give out the data that's requested from the buffers that we have + * queued up per port + */ +static ssize_t fill_readbuf(struct virtio_console_port *port, + char *out_buf, size_t out_count, bool to_user) +{ + struct virtio_console_port_buffer *buf, *buf2; + ssize_t out_offset, ret; + + out_offset = 0; + /* + * Not taking the port->readbuf_list_lock here relying on the + * fact that buffers are taken out from the list only in this + * function so buf2 should be available all the time. + * + * Also, copy_to_user() might sleep. + */ + list_for_each_entry_safe(buf, buf2, &port->readbuf_head, next) { + size_t copy_size; + + copy_size = out_count; + if (copy_size > buf->len - buf->offset) + copy_size = buf->len - buf->offset; + + 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 */ + } + + /* Return the number of bytes actually copied */ + ret = copy_size - ret; + buf->offset += ret; + out_offset += ret; + out_count -= ret; + + if (buf->len - buf->offset == 0) { + spin_lock(&port->readbuf_list_lock); + list_del(&buf->next); + spin_unlock(&port->readbuf_list_lock); + kfree(buf->buf); + kfree(buf); + } + if (!out_count) + break; + } + return out_offset; +} + +/* The condition that must be true for polling to end */ +static bool wait_is_over(struct virtio_console_port *port) +{ + return !list_empty(&port->readbuf_head) || !port->host_connected; +} + +static ssize_t virtconsole_read(struct file *filp, char __user *ubuf, + size_t count, loff_t *offp) +{ + struct virtio_console_port *port; + ssize_t ret; + + port = filp->private_data; + + if (list_empty(&port->readbuf_head)) { + /* + * If nothing's connected on the host just return 0 in + * case of list_empty; this tells the userspace app + * that there's no connection + */ + if (!port->host_connected) return 0; + if (filp->f_flags & O_NONBLOCK) + return -EAGAIN; + + ret = wait_event_interruptible(port->waitqueue, + wait_is_over(port)); + if (ret < 0) + return ret; + } + /* + * We could've received a disconnection message while we were + * waiting for more data. + * + * This check is not clubbed in the if() statement above as we + * might receive some data as well as the host could get + * disconnected after we got woken up from our wait. So we + * really want to give off whatever data we have and only then + * check for host_connected + */ + if (list_empty(&port->readbuf_head) && !port->host_connected) + return 0; + + return fill_readbuf(port, ubuf, count, true); +} + +static ssize_t send_buf(struct virtio_console_port *port, + const char *in_buf, size_t in_count, + u32 flags, bool from_user) +{ + struct virtqueue *out_vq; + struct virtio_console_port_buffer *buf, *buf2; + struct scatterlist sg[1]; + struct virtio_console_header header; + size_t in_offset, copy_size; + ssize_t ret; + unsigned int header_len; + + if (!in_count) + return 0; + + out_vq = port->vcon->out_vq; + /* + * We should not send internal messages to a host that won't + * understand them + */ + if (!use_multiport(port->vcon) && is_internal(flags)) + return 0; + header_len = 0; + if (use_multiport(port->vcon)) { + header.id = get_id_from_port(port); + header.flags = flags; + header.size = in_count; + header_len = sizeof(header); } + in_offset = 0; /* offset in the user buffer */ + while (in_count - in_offset) { + copy_size = min(in_count - in_offset + header_len, PAGE_SIZE); - /* You want more than we have to give? Well, try wanting less! */ - if (in_len < count) - count = in_len; + spin_lock(&port->vcon->write_list_lock); + list_for_each_entry_safe(buf, buf2, + &port->vcon->unused_write_head, + next) { + list_del(&buf->next); + break; + } + spin_unlock(&port->vcon->write_list_lock); + if (!buf) + break; + if (header_len) { + memcpy(buf->buf, &header, header_len); + copy_size -= header_len; + } + if (from_user) + ret = copy_from_user(buf->buf + header_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 in_buf + */ + memcpy(buf->buf + header_len, + in_buf + in_offset, copy_size); + ret = 0; /* Emulate copy_from_user behaviour */ + } + buf->len = header_len + copy_size - ret; + sg_init_one(sg, buf->buf, buf->len); - /* Copy across to their buffer and increment offset. */ - memcpy(buf, in, count); - in += count; - in_len -= count; + spin_lock(&port->vcon->write_list_lock); + ret = out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, buf); + spin_unlock(&port->vcon->write_list_lock); + if (ret < 0) { + memset(buf->buf, 0, buf->len); + spin_lock(&virtconsole.write_list_lock); + list_add_tail(&buf->next, + &port->vcon->unused_write_head); + spin_unlock(&port->vcon->write_list_lock); + break; + } + in_offset += buf->len - header_len; + /* + * Only send size with the first buffer. This way + * userspace can find out a continuous stream of data + * belonging to one write request and consume it + * appropriately + */ + header.size = 0; - /* Finished? Re-register buffer so Host will use it again. */ - if (in_len == 0) - add_inbuf(); + /* No space left in the vq anyway */ + if (!ret) + break; + } + /* Tell Host to go! */ + spin_lock(&port->vcon->write_list_lock); + out_vq->vq_ops->kick(out_vq); + spin_unlock(&port->vcon->write_list_lock); - return count; + /* We're expected to return the amount of data we wrote */ + return in_offset; } -/*:*/ -/*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. +static ssize_t virtconsole_write(struct file *filp, const char __user *ubuf, + size_t count, loff_t *offp) +{ + struct virtio_console_port *port; + + port = filp->private_data; + + return send_buf(port, ubuf, count, 0, true); +} + +static unsigned int virtconsole_poll(struct file *filp, poll_table *wait) +{ + struct virtio_console_port *port; + unsigned int ret; + + port = filp->private_data; + poll_wait(filp, &port->waitqueue, wait); + + ret = 0; + if (!list_empty(&port->readbuf_head)) + ret |= POLLIN | POLLRDNORM; + if (!port->host_connected) + ret |= POLLHUP; + + return ret; +} + +static int virtconsole_release(struct inode *inode, struct file *filp) +{ + struct virtio_console_control cpkt; + + /* Notify host of port being closed */ + cpkt.event = VIRTIO_CONSOLE_PORT_OPEN; + cpkt.value = 0; + send_buf(filp->private_data, (char *)&cpkt, sizeof(cpkt), + VIRTIO_CONSOLE_ID_INTERNAL, false); + return 0; +} + +static int virtconsole_open(struct inode *inode, struct file *filp) +{ + struct cdev *cdev = inode->i_cdev; + struct virtio_console_port *port; + struct virtio_console_control cpkt; + + port = container_of(cdev, struct virtio_console_port, cdev); + filp->private_data = port; + + /* Notify host of port being opened */ + cpkt.event = VIRTIO_CONSOLE_PORT_OPEN; + cpkt.value = 1; + send_buf(filp->private_data, (char *)&cpkt, sizeof(cpkt), + VIRTIO_CONSOLE_ID_INTERNAL, false); + + return 0; +} + +/* + * The file operations that we support: programs in the guest can open + * a console device, read from it, write to it, poll for data and + * close it. The devices are at /dev/vconNN + */ +static const struct file_operations virtconsole_fops = { + .owner = THIS_MODULE, + .open = virtconsole_open, + .read = virtconsole_read, + .write = virtconsole_write, + .poll = virtconsole_poll, + .release = virtconsole_release, +}; + + +static ssize_t show_port_name(struct device *dev, + struct device_attribute *attr, char *buffer) +{ + struct virtio_console_port *port; + + port = get_port_from_devt(dev->devt); + if (!port || !port->name) + return 0; + + return sprintf(buffer, "%s\n", port->name); +} + +static DEVICE_ATTR(name, S_IRUGO, show_port_name, NULL); + +static struct attribute *virtcon_sysfs_entries[] = { + &dev_attr_name.attr, + NULL +}; + +static struct attribute_group virtcon_attribute_group = { + .name = NULL, /* put in device directory */ + .attrs = virtcon_sysfs_entries, +}; + + +/*D:310 + * The cons_put_chars() callback is pretty straightforward. * - * 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)) + * We turn the characters into a scatter-gather list, add it to the output + * queue and then kick the Host. + * + * If the data to be outpu spans more than a page, it's split into + * page-sized buffers and then individual buffers are pushed to Host. + */ +static int cons_put_chars(u32 vtermno, const char *buf, int count) { - virtio_cons.put_chars = put_chars; - return hvc_instantiate(0, 0, &virtio_cons); + struct virtio_console_port *port; + + port = get_port_from_vtermno(vtermno); + if (!port) + return 0; + + return send_buf(port, buf, count, 0, false); } +/*D:350 + * cons_get_chars() is the callback from the hvc_console + * infrastructure when an interrupt is received. + * + * We call out to fill_readbuf that gets us the required data from the + * buffers that are queued up. + */ +static int cons_get_chars(u32 vtermno, char *buf, int count) +{ + struct virtio_console_port *port; + + /* If we don't have an input queue yet, we can't get input. */ + BUG_ON(!virtconsole.in_vq); + + port = get_port_from_vtermno(vtermno); + if (!port) + return 0; + + if (list_empty(&port->readbuf_head)) + return 0; + + return fill_readbuf(port, buf, count, false); +} +/*:*/ + /* * virtio console configuration. This supports: * - console resize @@ -153,98 +555,572 @@ static void virtcons_apply_config(struct virtio_device *dev) dev->config->get(dev, offsetof(struct virtio_console_config, rows), &ws.ws_row, sizeof(u16)); - hvc_resize(hvc, ws); + /* + * We'll use this way of resizing only for legacy + * support. For newer userspace (VIRTIO_CONSOLE_F_MULTPORT+), + * use internal messages to indicate console size + * changes so that it can be done per-port + */ + if (!use_multiport(&virtconsole)) + hvc_resize(get_port_from_id(0)->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) +static int cons_notifier_add_vio(struct hvc_struct *hp, int data) { hp->irq_requested = 1; - virtcons_apply_config(vdev); + virtcons_apply_config(virtconsole.vdev); return 0; } -static void notifier_del_vio(struct hvc_struct *hp, int data) +static void cons_notifier_del_vio(struct hvc_struct *hp, int data) { hp->irq_requested = 0; } -static void hvc_handle_input(struct virtqueue *vq) +/* The operations for our console. */ +static struct hv_ops virtio_cons = { + .get_chars = cons_get_chars, + .put_chars = cons_put_chars, + .notifier_add = cons_notifier_add_vio, + .notifier_del = cons_notifier_del_vio, + .notifier_hangup = cons_notifier_del_vio, +}; + +/*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); +} + +int init_port_console(struct virtio_console_port *port) { - if (hvc_poll(hvc)) - hvc_kick(); + int ret = 0; + + /* + * The Host's telling us this port is a console port. Hook it + * up with an hvc console. + * + * To set up and manage our virtual console, we call + * hvc_alloc(). + * + * The first argument of hvc_alloc() is the virtual console + * number. 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. + */ + port->hvc = hvc_alloc(hvc_vtermno, 0, &virtio_cons, PAGE_SIZE); + if (IS_ERR(port->hvc)) { + ret = PTR_ERR(port->hvc); + pr_err("%s: Could not alloc hvc for virtio console port, ret = %d\n", + __func__, ret); + port->hvc = NULL; + } else + port->vtermno = hvc_vtermno++; + return ret; } -/*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. +/* Any secret messages that the Host and Guest want to share */ +static void handle_control_message(struct virtio_console_port *port, + struct virtio_console_port_buffer *buf) +{ + struct virtio_console_control *cpkt; + size_t name_size; + + cpkt = (struct virtio_console_control *)(buf->buf + buf->offset); + + switch (cpkt->event) { + case VIRTIO_CONSOLE_PORT_OPEN: + port->host_connected = cpkt->value; + break; + case VIRTIO_CONSOLE_PORT_NAME: + /* + * Skip the size of the header and the cpkt to get the size + * of the name that was sent + */ + name_size = buf->len - buf->offset - sizeof(*cpkt) + 1; + + port->name = kmalloc(name_size, GFP_KERNEL); + if (!port->name) { + pr_err("%s: not enough space to store port name\n", + __func__); + break; + } + strncpy(port->name, buf->buf + buf->offset + sizeof(*cpkt), + name_size - 1); + port->name[name_size - 1] = 0; + break; + case VIRTIO_CONSOLE_CONSOLE_PORT: + if (!cpkt->value) + break; + init_port_console(port); + /* + * Could remove the port here in case init fails - but + * have to notify the host first + */ + break; + } +} + + +static struct virtio_console_port_buffer *get_buf(size_t buf_size) +{ + struct virtio_console_port_buffer *buf; + + buf = kzalloc(sizeof(*buf), GFP_KERNEL); + if (!buf) + goto out; + buf->buf = kzalloc(buf_size, GFP_KERNEL); + if (!buf->buf) { + kfree(buf); + goto out; + } + buf->len = buf_size; +out: + return buf; +} + +static void fill_queue(struct virtqueue *vq, size_t buf_size, + struct list_head *unused_head) +{ + struct scatterlist sg[1]; + struct virtio_console_port_buffer *buf; + int ret; + + do { + buf = get_buf(buf_size); + if (!buf) + break; + sg_init_one(sg, buf->buf, buf_size); + + ret = vq->vq_ops->add_buf(vq, sg, 0, 1, buf); + if (ret < 0) { + kfree(buf->buf); + kfree(buf); + break; + } + /* + * We have to keep track of the unused buffers so that + * they can be freed when the module is being removed + */ + list_add_tail(&buf->next, unused_head); + } while (ret > 0); + vq->vq_ops->kick(vq); +} + +static void fill_receive_queue(struct virtio_console_struct *vcon) +{ + fill_queue(vcon->in_vq, PAGE_SIZE, &vcon->unused_read_head); +} + +/* + * This function is only called from the init routine so the spinlock + * for the unused_write_head list isn't taken + */ +static void alloc_write_bufs(struct virtio_console_struct *vcon) +{ + struct virtio_console_port_buffer *buf; + int i; + + for (i = 0; i < 1024; i++) { + buf = get_buf(PAGE_SIZE); + if (!buf) + break; + list_add_tail(&buf->next, &vcon->unused_write_head); + } +} + +/* + * The workhandler for any buffers that appear on our input queue. + * Pick the buffer; if it's some internal communication meant for the + * us, just process it. Otherwise queue it up for the read() or + * get_chars() routines to pick the data up later. + */ +static void virtio_console_rx_work_handler(struct work_struct *work) +{ + struct virtio_console_struct *vcon; + struct virtio_console_port *port; + struct virtio_console_port_buffer *buf; + struct virtio_console_header header; + struct virtqueue *vq; + unsigned int tmplen, header_len; + + vcon = container_of(work, struct virtio_console_struct, rx_work); + header_len = use_multiport(vcon) ? sizeof(header) : 0; + + port = NULL; + vq = vcon->in_vq; + while ((buf = vq->vq_ops->get_buf(vq, &tmplen))) { + /* The buffer is no longer unused */ + list_del(&buf->next); + + if (use_multiport(vcon)) { + memcpy(&header, buf->buf, header_len); + port = get_port_from_id(header.id); + } else + port = get_port_from_id(0); + if (!port) { + /* No valid header at start of buffer. Drop it. */ + pr_debug("%s: invalid index in buffer, %c %d\n", + __func__, buf->buf[0], buf->buf[0]); + /* + * OPT: This buffer can be added to the unused + * list to avoid free / alloc + */ + kfree(buf->buf); + kfree(buf); + break; + } + buf->len = tmplen; + buf->offset = header_len; + if (use_multiport(vcon) && is_internal(header.flags)) { + handle_control_message(port, buf); + /* + * OPT: This buffer can be added to the unused + * list to avoid free/alloc + */ + kfree(buf->buf); + kfree(buf); + } else { + spin_lock(&port->readbuf_list_lock); + list_add_tail(&buf->next, &port->readbuf_head); + spin_unlock(&port->readbuf_list_lock); + /* + * We might have missed a connection + * notification, e.g. before the queues were + * initialised. + */ + port->host_connected = true; + } + wake_up_interruptible(&port->waitqueue); + + if (is_console_port(port) && !list_empty(&port->readbuf_head)) + if (hvc_poll(port->hvc)) + hvc_kick(); + } + /* Allocate buffers for all the ones that got used up */ + fill_receive_queue(&virtconsole); +} + +/* + * This is the workhandler for buffers that get received on the output + * virtqueue, which is an indication that Host consumed the data we + * sent it. Since all our buffers going out are of a fixed size we can + * just reuse them instead of freeing them and allocating new ones. + * + * Zero out the buffer so that we don't leak any information from + * other processes. There's a small optimisation here as well: the + * buffers are PAGE_SIZE-sized; but instead of zeroing the entire + * page, we just zero the length that was most recently used and we + * can be sure the rest of the page is already set to 0s. + * + * So once we zero them out we add them back to the unused buffers + * list + */ +static void virtio_console_tx_work_handler(struct work_struct *work) +{ + struct virtio_console_struct *vcon; + struct virtqueue *vq; + struct virtio_console_port_buffer *buf; + unsigned int tmplen; + + vcon = container_of(work, struct virtio_console_struct, tx_work); + + vq = vcon->out_vq; + spin_lock(&vcon->write_list_lock); + while ((buf = vq->vq_ops->get_buf(vq, &tmplen))) { + /* 0 the buffer to not leak data from other processes */ + memset(buf->buf, 0, buf->len); + list_add_tail(&buf->next, &vcon->unused_write_head); + } + spin_unlock(&vcon->write_list_lock); +} + +static void rx_intr(struct virtqueue *vq) +{ + schedule_work(&virtconsole.rx_work); +} + +static void tx_intr(struct virtqueue *vq) +{ + schedule_work(&virtconsole.tx_work); +} + +static void config_intr(struct virtio_device *vdev) +{ + if (use_multiport(&virtconsole)) { + /* Handle port hot-add */ + schedule_work(&virtconsole.config_work); + } + /* Handle console size changes */ + virtcons_apply_config(vdev); +} + +static int virtconsole_add_port(u32 port_nr) +{ + struct virtio_console_port *port; + struct virtio_console_control cpkt; + dev_t devt; + int ret; + + port = kzalloc(sizeof(*port), GFP_KERNEL); + if (!port) + return -ENOMEM; + + port->vcon = &virtconsole; + port->id = port_nr; + + cdev_init(&port->cdev, &virtconsole_fops); + + ret = alloc_chrdev_region(&devt, 0, 1, "virtio-console"); + if (ret < 0) { + pr_err("%s: error allocing chrdev region, ret = %d\n", + __func__, ret); + goto free_port; + } + ret = cdev_add(&port->cdev, devt, 1); + if (ret < 0) { + pr_err("%s: error adding cdev, ret = %d\n", __func__, ret); + goto free_chrdev; + } + port->dev = device_create(port->vcon->class, NULL, devt, NULL, + "vcon%u", port_nr); + if (IS_ERR(port->dev)) { + ret = PTR_ERR(port->dev); + pr_err("%s: error creating device, ret = %d\n", __func__, ret); + goto free_cdev; + } + ret = sysfs_create_group(&port->dev->kobj, &virtcon_attribute_group); + if (ret) { + pr_err("%s: error creating sysfs device attributes, ret = %d\n", + __func__, ret); + goto free_cdev; + } + + spin_lock_init(&port->readbuf_list_lock); + INIT_LIST_HEAD(&port->readbuf_head); + init_waitqueue_head(&port->waitqueue); + + list_add_tail(&port->next, &port->vcon->port_head); + + /* + * Ask for the port's name from Host. The string that we + * receive in 'name' can be of arbitrary length; so pass the + * maximum available buffer size: PAGE_SIZE. + */ + cpkt.event = VIRTIO_CONSOLE_PORT_NAME; + send_buf(port, (char *)&cpkt, sizeof(cpkt), + VIRTIO_CONSOLE_ID_INTERNAL, false); + + /* + * If we're not using multiport support, this has to be a console port + */ + if (!use_multiport(&virtconsole)) { + ret = init_port_console(port); + if (ret) + goto free_cdev; + } + return 0; +free_cdev: + cdev_del(&port->cdev); +free_chrdev: + unregister_chrdev_region(devt, 1); +free_port: + kfree(port); + return ret; +} + + +/* The workhandler for config-space updates * - * To set up and manage our virtual console, we call hvc_alloc(). Since we - * never remove the console device we never need this pointer again. + * This is used when new ports are added + */ +static void virtio_console_config_work_handler(struct work_struct *work) +{ + struct virtio_console_struct *vcon; + struct virtio_console_config virtconconf; + struct virtio_device *vdev; + u32 i; + int ret; + + vcon = container_of(work, struct virtio_console_struct, config_work); + + vdev = vcon->vdev; + vdev->config->get(vdev, + offsetof(struct virtio_console_config, nr_active_ports), + &virtconconf.nr_active_ports, + sizeof(virtconconf.nr_active_ports)); + + /* Hot-add ports */ + for (i = virtconsole.config.nr_active_ports; + i < virtconconf.nr_active_ports; i++) { + ret = virtconsole_add_port(virtconsole.config.nr_active_ports + i); + if (!ret) + virtconsole.config.nr_active_ports++; + } +} + +/*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. * - * Finally we put our input buffer in the input queue, ready to receive. */ -static int __devinit virtcons_probe(struct virtio_device *dev) + * Finally we put our input buffer in the input queue, ready to receive. + */ +static int __devinit virtcons_probe(struct virtio_device *vdev) { - vq_callback_t *callbacks[] = { hvc_handle_input, NULL}; + vq_callback_t *callbacks[] = { rx_intr, tx_intr }; const char *names[] = { "input", "output" }; struct virtqueue *vqs[2]; - int err; - - vdev = dev; + u32 i; + int ret; + bool multiport; - /* This is the scratch page we use to receive console input */ - inbuf = kmalloc(PAGE_SIZE, GFP_KERNEL); - if (!inbuf) { - err = -ENOMEM; - goto fail; + if (virtconsole.vdev) { + pr_err("Multiple virtio-console devices not supported yet\n"); + return -EEXIST; } + virtconsole.vdev = vdev; + + multiport = false; + if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_MULTIPORT)) { + multiport = true; + vdev->features[0] |= 1 << VIRTIO_CONSOLE_F_MULTIPORT; + vdev->config->finalize_features(vdev); + vdev->config->get(vdev, offsetof(struct virtio_console_config, + nr_active_ports), + &virtconsole.config.nr_active_ports, + sizeof(virtconsole.config.nr_active_ports)); + } /* Find the queues. */ /* FIXME: This is why we want to wean off hvc: we do nothing * when input comes in. */ - err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names); - if (err) - goto free; + ret = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names); + if (ret) + goto fail; - in_vq = vqs[0]; - out_vq = vqs[1]; + virtconsole.in_vq = vqs[0]; + virtconsole.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; + /* + * We had set the virtio_cons put_chars implementation to + * put_chars for early_init. Now that we're done with the + * early init phase, replace it with our cons_put_chars + * implementation. + */ + virtio_cons.put_chars = cons_put_chars; + + INIT_LIST_HEAD(&virtconsole.port_head); + INIT_LIST_HEAD(&virtconsole.unused_read_head); + INIT_LIST_HEAD(&virtconsole.unused_write_head); + + INIT_WORK(&virtconsole.rx_work, &virtio_console_rx_work_handler); + INIT_WORK(&virtconsole.tx_work, &virtio_console_tx_work_handler); + INIT_WORK(&virtconsole.config_work, &virtio_console_config_work_handler); + spin_lock_init(&virtconsole.write_list_lock); + + fill_receive_queue(&virtconsole); + alloc_write_bufs(&virtconsole); + + virtconsole_add_port(0); + if (multiport) + for (i = 1; i < virtconsole.config.nr_active_ports; i++) + virtconsole_add_port(i); + + return 0; + +fail: + return ret; +} + +/* + * Remove port-specific data. + * In case the port can't be removed, return non-zero. This could + * then be used in the port hot-unplug case. + */ +static int virtcons_remove_port_data(struct virtio_console_port *port) +{ + struct virtio_console_port_buffer *buf, *buf2; + + if (is_console_port(port)) { + /* hvc_console is compiled in, at least on Fedora. */ + /* hvc_remove(hvc); */ + return 1; } - /* Register the input buffer the first time. */ - add_inbuf(); + sysfs_remove_group(&port->dev->kobj, &virtcon_attribute_group); + device_destroy(virtconsole.class, port->dev->devt); + unregister_chrdev_region(port->dev->devt, 1); + cdev_del(&port->cdev); + + kfree(port->name); + + /* Remove the buffers in which we have unconsumed data */ + spin_lock(&port->readbuf_list_lock); + list_for_each_entry_safe(buf, buf2, &port->readbuf_head, next) { + list_del(&buf->next); + kfree(buf->buf); + kfree(buf); + } + spin_unlock(&port->readbuf_list_lock); return 0; +} + +static void virtcons_remove(struct virtio_device *vdev) +{ + struct virtio_console_port *port, *port2; + struct virtio_console_port_buffer *buf, *buf2; + char *tmpbuf; + int len; + + class_destroy(virtconsole.class); + + cancel_work_sync(&virtconsole.rx_work); + /* + * Free up the buffers that we queued up for the Host to pass + * us data + */ + while ((tmpbuf = virtconsole.in_vq->vq_ops->get_buf(virtconsole.in_vq, + &len))) + kfree(tmpbuf); -free_vqs: vdev->config->del_vqs(vdev); -free: - kfree(inbuf); -fail: - return err; + /* + * Free up the buffers that were sent to us by Host but were + * left unused + */ + list_for_each_entry_safe(buf, buf2, &virtconsole.unused_read_head, next) { + list_del(&buf->next); + kfree(buf->buf); + kfree(buf); + } + list_for_each_entry_safe(buf, buf2, &virtconsole.unused_write_head, next) { + list_del(&buf->next); + kfree(buf->buf); + kfree(buf); + } + list_for_each_entry_safe(port, port2, &virtconsole.port_head, next) { + list_del(&port->next); + virtcons_remove_port_data(port); + kfree(port); + } } static struct virtio_device_id id_table[] = { @@ -254,6 +1130,7 @@ static struct virtio_device_id id_table[] = { static unsigned int features[] = { VIRTIO_CONSOLE_F_SIZE, + VIRTIO_CONSOLE_F_MULTIPORT, }; static struct virtio_driver virtio_console = { @@ -263,14 +1140,34 @@ static struct virtio_driver virtio_console = { .driver.owner = THIS_MODULE, .id_table = id_table, .probe = virtcons_probe, - .config_changed = virtcons_apply_config, + .remove = virtcons_remove, + .config_changed = config_intr, }; static int __init init(void) { - return register_virtio_driver(&virtio_console); + int ret; + + virtconsole.class = class_create(THIS_MODULE, "virtio-console"); + if (IS_ERR(virtconsole.class)) { + pr_err("Error creating virtio-console class\n"); + ret = PTR_ERR(virtconsole.class); + return ret; + } + ret = register_virtio_driver(&virtio_console); + if (ret) { + class_destroy(virtconsole.class); + return ret; + } + return 0; +} + +static void __exit fini(void) +{ + unregister_virtio_driver(&virtio_console); } module_init(init); +module_exit(fini); MODULE_DEVICE_TABLE(virtio, id_table); MODULE_DESCRIPTION("Virtio console driver"); diff --git a/include/linux/virtio_console.h b/include/linux/virtio_console.h index b5f5198..96bb6f0 100644 --- a/include/linux/virtio_console.h +++ b/include/linux/virtio_console.h @@ -2,19 +2,63 @@ #define _LINUX_VIRTIO_CONSOLE_H #include <linux/types.h> #include <linux/virtio_config.h> -/* This header, excluding the #ifdef __KERNEL__ part, is BSD licensed so - * anyone can use the definitions to implement compatible drivers/servers. */ +/* + * This header, excluding the #ifdef __KERNEL__ part, is BSD licensed so + * anyone can use the definitions to implement compatible drivers/servers. + * + * Copyright (C) Red Hat, Inc., 2009 + */ /* Feature bits */ #define VIRTIO_CONSOLE_F_SIZE 0 /* Does host provide console size? */ +#define VIRTIO_CONSOLE_F_MULTIPORT 1 /* Does host provide multiple ports? */ + +#define VIRTIO_CONSOLE_BAD_ID (~(u32)0) /* Invalid port number */ struct virtio_console_config { /* colums of the screens */ __u16 cols; /* rows of the screens */ __u16 rows; + /* number of ports in use */ + __u32 nr_active_ports; +} __attribute__((packed)); + + +/* + * An internal-only message that's passed between the Host and the + * Guest for a particular port. + */ +struct virtio_console_control { + __u16 event; + __u16 value; +}; + +/* Some events for internal messages (control packets) */ +#define VIRTIO_CONSOLE_PORT_OPEN 0 +#define VIRTIO_CONSOLE_PORT_NAME 1 +#define VIRTIO_CONSOLE_CONSOLE_PORT 2 + + +/* + * This struct is put in each buffer that gets passed to userspace and + * vice-versa + */ +struct virtio_console_header { + /* Port number */ + u32 id; + /* Some message between host and guest */ + u32 flags; + /* + * Complete size of the write request - only sent with the + * first buffer for each write request + */ + u32 size; } __attribute__((packed)); +/* Messages between host and guest ('flags' field in the header above) */ +#define VIRTIO_CONSOLE_ID_INTERNAL (1 << 0) + #ifdef __KERNEL__ int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int)); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Amit Shah on 6 Oct 2009 03:10
On (Tue) Oct 06 2009 [08:49:22], Christian Borntraeger wrote: > Am Montag 05 Oktober 2009 16:05:35 schrieb Amit Shah: > > On (Thu) Oct 01 2009 [12:28:30], Christian Borntraeger wrote: > > > With the latest git kernel + your patch I sometmes get a completely > > > frozen console. In the dump there is > > > > > > <3>virtio_console virtio0: output:id 68 is not a head! > > > > > > Seems that I can reproduce it with large amounts of output (find / for > > > example) Without your patch everything is fine. > > > > Hey Christian, > > > > Can you try this patch? > > This version seems to work on s390. Thanks Great; thanks for the confirmation. The race I'm seeing could be due to some misconfiguration in qemu then. Amit -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |