On Thu, Mar 19, 2015 at 10:13:11AM +0100, Gerd Hoffmann wrote:
> virtio-input is basically evdev-events-over-virtio, so this driver isn't
> much more than reading configuration from config space and forwarding
> incoming events to the linux input layer.
>
> Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
What worries me is how well are these events specified.
Will we be able to write drivers for non-linux guests?
Not sure where to discuss this - this seems like an inappropriate
thread.
Comments on linux driver below.
> ---
> drivers/virtio/Kconfig | 10 ++
> drivers/virtio/Makefile | 1 +
> drivers/virtio/virtio_input.c | 313 ++++++++++++++++++++++++++++++++++++++
> include/uapi/linux/virtio_ids.h | 1 +
> include/uapi/linux/virtio_input.h | 65 ++++++++
> 5 files changed, 390 insertions(+)
> create mode 100644 drivers/virtio/virtio_input.c
> create mode 100644 include/uapi/linux/virtio_input.h
>
> diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
> index b546da5..cab9f3f 100644
> --- a/drivers/virtio/Kconfig
> +++ b/drivers/virtio/Kconfig
> @@ -48,6 +48,16 @@ config VIRTIO_BALLOON
>
> If unsure, say M.
>
> +config VIRTIO_INPUT
> + tristate "Virtio input driver"
> + depends on VIRTIO
> + depends on INPUT
> + ---help---
> + This driver supports virtio input devices such as
> + keyboards, mice and tablets.
> +
> + If unsure, say M.
> +
> config VIRTIO_MMIO
> tristate "Platform bus driver for memory mapped virtio devices"
> depends on HAS_IOMEM
> diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile
> index d85565b..41e30e3 100644
> --- a/drivers/virtio/Makefile
> +++ b/drivers/virtio/Makefile
> @@ -4,3 +4,4 @@ obj-$(CONFIG_VIRTIO_PCI) += virtio_pci.o
> virtio_pci-y := virtio_pci_modern.o virtio_pci_common.o
> virtio_pci-$(CONFIG_VIRTIO_PCI_LEGACY) += virtio_pci_legacy.o
> obj-$(CONFIG_VIRTIO_BALLOON) += virtio_balloon.o
> +obj-$(CONFIG_VIRTIO_INPUT) += virtio_input.o
> diff --git a/drivers/virtio/virtio_input.c b/drivers/virtio/virtio_input.c
> new file mode 100644
> index 0000000..2d425cf
> --- /dev/null
> +++ b/drivers/virtio/virtio_input.c
> @@ -0,0 +1,313 @@
> +#include <linux/module.h>
> +#include <linux/virtio.h>
> +#include <linux/input.h>
> +
> +#include <uapi/linux/virtio_ids.h>
> +#include <uapi/linux/virtio_input.h>
> +
> +struct virtio_input {
> + struct virtio_device *vdev;
> + struct input_dev *idev;
> + char name[64];
> + char serial[64];
> + char phys[64];
> + struct virtqueue *evt, *sts;
> + struct virtio_input_event evts[64];
> +};
> +
> +static ssize_t serial_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct input_dev *idev = to_input_dev(dev);
> + struct virtio_input *vi = input_get_drvdata(idev);
> + return sprintf(buf, "%s\n", vi->serial);
> +}
> +static DEVICE_ATTR_RO(serial);
> +
> +static struct attribute *dev_attrs[] = {
> + &dev_attr_serial.attr,
> + NULL
> +};
> +
> +static umode_t dev_attrs_are_visible(struct kobject *kobj,
> + struct attribute *a, int n)
> +{
> + struct device *dev = container_of(kobj, struct device, kobj);
> + struct input_dev *idev = to_input_dev(dev);
> + struct virtio_input *vi = input_get_drvdata(idev);
> +
> + if (a == &dev_attr_serial.attr && !strlen(vi->serial))
> + return 0;
> +
> + return a->mode;
> +}
> +
> +static struct attribute_group dev_attr_grp = {
> + .attrs = dev_attrs,
> + .is_visible = dev_attrs_are_visible,
> +};
> +
> +static const struct attribute_group *dev_attr_groups[] = {
> + &dev_attr_grp,
> + NULL
> +};
> +
> +static void virtinput_queue_evtbuf(struct virtio_input *vi,
> + struct virtio_input_event *evtbuf)
> +{
> + struct scatterlist sg[1];
> +
> + sg_init_one(sg, evtbuf, sizeof(*evtbuf));
> + virtqueue_add_inbuf(vi->evt, sg, 1, evtbuf, GFP_ATOMIC);
> +}
> +
> +static void virtinput_recv_events(struct virtqueue *vq)
> +{
> + struct virtio_input *vi = vq->vdev->priv;
> + struct virtio_input_event *event;
> + unsigned int len;
> +
> + while ((event = virtqueue_get_buf(vi->evt, &len)) != NULL) {
> + input_event(vi->idev,
> + le16_to_cpu(event->type),
> + le16_to_cpu(event->code),
> + le32_to_cpu(event->value));
> + virtinput_queue_evtbuf(vi, event);
> + }
> + virtqueue_kick(vq);
> +}
> +
> +static int virtinput_send_status(struct virtio_input *vi,
> + u16 type, u16 code, s32 value)
> +{
> + struct virtio_input_event *stsbuf;
> + struct scatterlist sg[1];
> +
> + stsbuf = kzalloc(sizeof(*stsbuf), GFP_ATOMIC);
> + if (!stsbuf)
> + return -ENOMEM;
Does this return an error to userspace?
If so it's not a good idea I think, GFP_ATOMIC failures are
transient conditions and should not be reported
to userspace.
Can use GFP_KERNEL here?
> +
> + stsbuf->type = cpu_to_le16(type);
> + stsbuf->code = cpu_to_le16(code);
> + stsbuf->value = cpu_to_le32(value);
> + sg_init_one(sg, stsbuf, sizeof(*stsbuf));
> + virtqueue_add_outbuf(vi->sts, sg, 1, stsbuf, GFP_ATOMIC);
This can fail if queue is full. What prevents this from happening?
> + virtqueue_kick(vi->sts);
Also what prevents multiple virtinput_send_status calls
from racing with each other? Is there locking at a higher level?
> + return 0;
> +}
> +
> +static void virtinput_recv_status(struct virtqueue *vq)
> +{
> + struct virtio_input *vi = vq->vdev->priv;
> + struct virtio_input_event *stsbuf;
> + unsigned int len;
> +
> + while ((stsbuf = virtqueue_get_buf(vi->sts, &len)) != NULL)
looks like this get_buf can race with add above.
Need some locking.
Also pls avoid != NULL, removing it makes code less verbose.
> + kfree(stsbuf);
> + virtqueue_kick(vq);
Why are you kicking here?
> +}
> +
> +static int virtinput_status(struct input_dev *idev, unsigned int type,
> + unsigned int code, int value)
> +{
> + struct virtio_input *vi = input_get_drvdata(idev);
> +
> + return virtinput_send_status(vi, type, code, value);
> +}
> +
> +static size_t virtinput_cfg_select(struct virtio_input *vi,
> + u8 select, u8 subsel)
> +{
> + u8 size;
> +
> + virtio_cwrite(vi->vdev, struct virtio_input_config, select, &select);
> + virtio_cwrite(vi->vdev, struct virtio_input_config, subsel, &subsel);
> + virtio_cread(vi->vdev, struct virtio_input_config, size, &size);
> + return size;
> +}
> +
> +static void virtinput_cfg_bits(struct virtio_input *vi, int select, int subsel,
> + unsigned long *bits, unsigned int bitcount)
> +{
> + unsigned int bit;
> + size_t bytes;
> + u8 cfg = 0;
> +
> + bytes = virtinput_cfg_select(vi, select, subsel);
> + if (!bytes)
> + return;
> + if (bitcount > bytes*8)
> + bitcount = bytes*8;
> + if (select == VIRTIO_INPUT_CFG_EV_BITS)
> + set_bit(subsel, vi->idev->evbit);
> + for (bit = 0; bit < bitcount; bit++) {
> + if ((bit % 8) == 0)
> + virtio_cread(vi->vdev, struct virtio_input_config,
> + u.bitmap[bit/8], &cfg);
coding style violations above. you need spaces around ops like / and *.
Please run checkpatch.pl
> + if (cfg & (1 << (bit % 8)))
> + set_bit(bit, bits);
what if not set? does something clear the mask?
> + }
doesn't above just implement bitmap_copy or bitmap_or? Will it hurt to
just do virtio_cread_bytes into a temporary buffer and then invoke
bitmap ops? Looks like the buffer is at most 256 bytes:
too large to be on stack, but you can allocate it at probe time.
> +}
> +
> +static void virtinput_cfg_abs(struct virtio_input *vi, int abs)
> +{
> + u32 size, mi, ma, fu, fl;
> +
> + size = virtinput_cfg_select(vi, VIRTIO_INPUT_CFG_ABS_INFO, abs);
> + virtio_cread(vi->vdev, struct virtio_input_config, u.abs.min, &mi);
> + virtio_cread(vi->vdev, struct virtio_input_config, u.abs.max, &ma);
> + virtio_cread(vi->vdev, struct virtio_input_config, u.abs.fuzz, &fu);
> + virtio_cread(vi->vdev, struct virtio_input_config, u.abs.flat, &fl);
you read le field into u32 value.
Please run sparse on this code. you will get a ton
of warnings. Same error appears elsewhere.
> + input_set_abs_params(vi->idev, abs,
> + le32_to_cpu(mi), le32_to_cpu(ma),
> + le32_to_cpu(fu), le32_to_cpu(fl));
> +}
> +
> +static int virtinput_init_vqs(struct virtio_input *vi)
> +{
> + struct virtqueue *vqs[2];
> + vq_callback_t *cbs[] = { virtinput_recv_events,
> + virtinput_recv_status };
> + const char *names[] = { "events", "status" };
> + int i, err, size;
> +
> + err = vi->vdev->config->find_vqs(vi->vdev, 2, vqs, cbs, names);
> + if (err)
> + return err;
> + vi->evt = vqs[0];
> + vi->sts = vqs[1];
> +
> + size = virtqueue_get_vring_size(vi->evt);
> + if (size > ARRAY_SIZE(vi->evts))
> + size = ARRAY_SIZE(vi->evts);
> + for (i = 0; i < size; i++)
> + virtinput_queue_evtbuf(vi, &vi->evts[i]);
> +
you add a bunch of bufs but never kick apparently.
you really must kick otherwise device might not
see the buffers.
> + return 0;
> +}
> +
> +static int virtinput_probe(struct virtio_device *vdev)
> +{
> + struct virtio_input *vi;
> + size_t size;
> + int abs, err;
How about checking VERSION_1 and bailing out of not there?
> +
> + vi = kzalloc(sizeof(*vi), GFP_KERNEL);
> + if (!vi) {
> + err = -ENOMEM;
> + goto out1;
> + }
> + vdev->priv = vi;
> + vi->vdev = vdev;
> +
> + err = virtinput_init_vqs(vi);
> + if (err)
> + goto out2;
> +
> + vi->idev = input_allocate_device();
> + if (!vi->idev) {
> + err = -ENOMEM;
> + goto out3;
> + }
> + input_set_drvdata(vi->idev, vi);
> +
> + size = virtinput_cfg_select(vi, VIRTIO_INPUT_CFG_ID_NAME, 0);
> + virtio_cread_bytes(vi->vdev, offsetof(struct virtio_input_config, u),
> + vi->name, min(size, sizeof(vi->name)));
> + size = virtinput_cfg_select(vi, VIRTIO_INPUT_CFG_ID_SERIAL, 0);
> + virtio_cread_bytes(vi->vdev, offsetof(struct virtio_input_config, u),
> + vi->serial, min(size, sizeof(vi->serial)));
> + snprintf(vi->phys, sizeof(vi->phys),
> + "virtio%d/input0", vdev->index);
> +
> + virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_PROP_BITS, 0,
> + vi->idev->propbit, INPUT_PROP_CNT);
> + size = virtinput_cfg_select(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_REP);
> + if (size)
> + set_bit(EV_REP, vi->idev->evbit);
> +
> + vi->idev->name = vi->name;
> + vi->idev->phys = vi->phys;
> + vi->idev->id.bustype = BUS_VIRTUAL;
> + vi->idev->id.vendor = 0x0001;
> + vi->idev->id.product = 0x0001;
> + vi->idev->id.version = 0x0100;
Add comments explaining why these #s make sense?
> + vi->idev->dev.parent = &vdev->dev;
> + vi->idev->dev.groups = dev_attr_groups;
> + vi->idev->event = virtinput_status;
> +
> + /* device -> kernel */
> + virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_KEY,
> + vi->idev->keybit, KEY_CNT);
> + virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_REL,
> + vi->idev->relbit, REL_CNT);
> + virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_ABS,
> + vi->idev->absbit, ABS_CNT);
> + virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_MSC,
> + vi->idev->mscbit, MSC_CNT);
> + virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_SW,
> + vi->idev->swbit, SW_CNT);
> +
> + /* kernel -> device */
> + virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_LED,
> + vi->idev->ledbit, LED_CNT);
> + virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_SND,
> + vi->idev->sndbit, SND_CNT);
> +
> + if (test_bit(EV_ABS, vi->idev->evbit)) {
> + for (abs = 0; abs < ABS_CNT; abs++) {
> + if (!test_bit(abs, vi->idev->absbit))
> + continue;
> + virtinput_cfg_abs(vi, abs);
> + }
> + }
> +
> + err = input_register_device(vi->idev);
Once you do this, virtinput_status can get called,
and that will kick, correct?
If so, you must call device_ready before this.
> + if (err)
> + goto out4;
> +
> + return 0;
> +
> +out4:
> + input_free_device(vi->idev);
> +out3:
> + vdev->config->del_vqs(vdev);
> +out2:
> + kfree(vi);
> +out1:
> + return err;
free on error is out of order with initialization.
Might lead to leaks or other bugs.
Also - can you name labels something sensible pls?
out is usually for exiting on success too...
E.g. out4 -> err_register etc.
> +}
> +
> +static void virtinput_remove(struct virtio_device *vdev)
> +{
> + struct virtio_input *vi = vdev->priv;
> +
> + input_unregister_device(vi->idev);
> + vdev->config->reset(vdev);
You don't really need a reset if you just to del_vqs.
People do this if they want to prevent interrupts
without deleting vqs.
> + vdev->config->del_vqs(vdev);
> + kfree(vi);
free_device seems to be missing?
> +}
> +
> +static unsigned int features[] = {
> +};
> +static struct virtio_device_id id_table[] = {
> + { VIRTIO_ID_INPUT, VIRTIO_DEV_ANY_ID },
> + { 0 },
> +};
> +
> +static struct virtio_driver virtio_input_driver = {
> + .driver.name = KBUILD_MODNAME,
> + .driver.owner = THIS_MODULE,
> + .feature_table = features,
> + .feature_table_size = ARRAY_SIZE(features),
> + .id_table = id_table,
> + .probe = virtinput_probe,
> + .remove = virtinput_remove,
> +};
> +
> +module_virtio_driver(virtio_input_driver);
> +MODULE_DEVICE_TABLE(virtio, id_table);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("Virtio input device driver");
> +MODULE_AUTHOR("Gerd Hoffmann <kraxel@xxxxxxxxxx>");
> diff --git a/include/uapi/linux/virtio_ids.h b/include/uapi/linux/virtio_ids.h
> index 284fc3a..5f60aa4 100644
> --- a/include/uapi/linux/virtio_ids.h
> +++ b/include/uapi/linux/virtio_ids.h
> @@ -39,5 +39,6 @@
> #define VIRTIO_ID_9P 9 /* 9p virtio console */
> #define VIRTIO_ID_RPROC_SERIAL 11 /* virtio remoteproc serial link */
> #define VIRTIO_ID_CAIF 12 /* Virtio caif */
> +#define VIRTIO_ID_INPUT 18 /* virtio input */
>
> #endif /* _LINUX_VIRTIO_IDS_H */
> diff --git a/include/uapi/linux/virtio_input.h b/include/uapi/linux/virtio_input.h
> new file mode 100644
> index 0000000..190d04a
> --- /dev/null
> +++ b/include/uapi/linux/virtio_input.h
> @@ -0,0 +1,65 @@
> +#ifndef _LINUX_VIRTIO_INPUT_H
> +#define _LINUX_VIRTIO_INPUT_H
> +/* This header is BSD licensed so anyone can use the definitions to implement
> + * compatible drivers/servers.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions
> + * are met:
> + * 1. Redistributions of source code must retain the above copyright
> + * notice, this list of conditions and the following disclaimer.
> + * 2. Redistributions in binary form must reproduce the above copyright
> + * notice, this list of conditions and the following disclaimer in the
> + * documentation and/or other materials provided with the distribution.
> + * 3. Neither the name of IBM nor the names of its contributors
> + * may be used to endorse or promote products derived from this software
> + * without specific prior written permission.
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
> + * ARE DISCLAIMED. IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
> + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
> + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
> + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
> + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
> + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
> + * SUCH DAMAGE. */
> +#include <linux/virtio_ids.h>
> +#include <linux/virtio_config.h>
> +
> +enum virtio_input_config_select {
> + VIRTIO_INPUT_CFG_UNSET = 0x00,
> + VIRTIO_INPUT_CFG_ID_NAME = 0x01,
> + VIRTIO_INPUT_CFG_ID_SERIAL = 0x02,
> + VIRTIO_INPUT_CFG_PROP_BITS = 0x10,
> + VIRTIO_INPUT_CFG_EV_BITS = 0x11,
> + VIRTIO_INPUT_CFG_ABS_INFO = 0x12,
> +};
> +
> +struct virtio_input_absinfo {
> + __le32 min;
> + __le32 max;
> + __le32 fuzz;
> + __le32 flat;
> +};
> +
> +struct virtio_input_config {
> + __u8 select;
> + __u8 subsel;
> + __u8 size;
> + __u8 reserved;
> + union {
> + char string[128];
> + __u8 bitmap[128];
> + struct virtio_input_absinfo abs;
> + } u;
> +};
> +
> +struct virtio_input_event {
> + __le16 type;
> + __le16 code;
> + __le32 value;
> +};
> +
> +#endif /* _LINUX_VIRTIO_INPUT_H */
> --
> 1.8.3.1
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