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Subject: Re: [PATCH v3] Add virtio-input driver.
On Tue, Mar 24, 2015 at 08:32:01AM +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@redhat.com>
Looks pretty neat overall. I think I still see some
small issues, but it's getting there.
> ---
> MAINTAINERS | 6 +
> drivers/virtio/Kconfig | 10 ++
> drivers/virtio/Makefile | 1 +
> drivers/virtio/virtio_input.c | 313 ++++++++++++++++++++++++++++++++++++++
> include/uapi/linux/Kbuild | 1 +
> include/uapi/linux/virtio_ids.h | 1 +
> include/uapi/linux/virtio_input.h | 76 +++++++++
> 7 files changed, 408 insertions(+)
> create mode 100644 drivers/virtio/virtio_input.c
> create mode 100644 include/uapi/linux/virtio_input.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 358eb01..6f233dd 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -10442,6 +10442,12 @@ S: Maintained
> F: drivers/vhost/
> F: include/uapi/linux/vhost.h
>
> +VIRTIO INPUT DRIVER
> +M: Gerd Hoffmann <kraxel@redhat.com>
> +S: Maintained
> +F: drivers/virtio/virtio_input.c
> +F: include/uapi/linux/virtio_input.h
> +
> VIA RHINE NETWORK DRIVER
> M: Roger Luethi <rl@hellgate.ch>
> S: Maintained
> 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..cf112b2
> --- /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];
> + spinlock_t lock;
> +};
> +
> +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 long flags;
> + unsigned int len;
> +
> + spin_lock_irqsave(&vi->lock, flags);
> + 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));
What happens if input layer gets an
unexpected event code or value?
Or does something prevent it?
> + virtinput_queue_evtbuf(vi, event);
> + }
> + virtqueue_kick(vq);
> + spin_unlock_irqrestore(&vi->lock, flags);
> +}
> +
> +static int virtinput_send_status(struct virtio_input *vi,
> + u16 type, u16 code, s32 value)
> +{
> + struct virtio_input_event *stsbuf;
> + struct scatterlist sg[1];
> + unsigned long flags;
> + int rc;
> +
> + stsbuf = kzalloc(sizeof(*stsbuf), GFP_ATOMIC);
> + if (!stsbuf)
> + return -ENOMEM;
> +
> + 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));
> +
> + spin_lock_irqsave(&vi->lock, flags);
> + rc = virtqueue_add_outbuf(vi->sts, sg, 1, stsbuf, GFP_ATOMIC);
> + virtqueue_kick(vi->sts);
> + spin_unlock_irqrestore(&vi->lock, flags);
> +
> + if (rc != 0)
> + kfree(stsbuf);
> + return rc;
This means that caller will get errors if it happens to call
send_status at a rate that's faster than host's consumption of them.
To me this looks wrong.
Poking at input layer, it seems to simply discard errors.
Is it always safe to discard status updates?
If yes, some kind of comment to clarify the logic would
make sense IMHO.
> +}
> +
> +static void virtinput_recv_status(struct virtqueue *vq)
> +{
> + struct virtio_input *vi = vq->vdev->priv;
> + struct virtio_input_event *stsbuf;
> + unsigned long flags;
> + unsigned int len;
> +
> + spin_lock_irqsave(&vi->lock, flags);
> + while ((stsbuf = virtqueue_get_buf(vi->sts, &len)) != NULL)
> + kfree(stsbuf);
> + spin_unlock_irqrestore(&vi->lock, flags);
> +}
> +
> +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 *virtio_bits;
> +
> + bytes = virtinput_cfg_select(vi, select, subsel);
> + if (!bytes)
> + return;
How about limiting bytes to sizeof struct virtio_input_config->u?
> + if (bitcount > bytes*8)
> + bitcount = bytes*8;
Space around * pls.
> +
> + /*
> + * Bitmap in virtio config space is a simple stream of bytes,
> + * with the first byte carrying bits 0-7, second bits 8-15 and
> + * so on.
> + */
> + virtio_bits = kzalloc(bytes, GFP_KERNEL);
> + if (!virtio_bits)
> + return;
> + virtio_cread_bytes(vi->vdev, offsetof(struct virtio_input_config, u),
> + virtio_bits, bytes);
> + for (bit = 0; bit < bitcount; bit++) {
> + if (virtio_bits[bit / 8] & (1 << (bit % 8)))
> + __set_bit(bit, bits);
> + }
> + kfree(virtio_bits);
> +
> + if (select == VIRTIO_INPUT_CFG_EV_BITS)
> + __set_bit(subsel, vi->idev->evbit);
> +}
> +
> +static void virtinput_cfg_abs(struct virtio_input *vi, int abs)
> +{
> + u32 mi, ma, re, fu, fl;
> +
> + 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.res, &re);
> + virtio_cread(vi->vdev, struct virtio_input_config, u.abs.fuzz, &fu);
> + virtio_cread(vi->vdev, struct virtio_input_config, u.abs.flat, &fl);
> + input_set_abs_params(vi->idev, abs, mi, ma, fu, fl);
> + input_abs_set_res(vi->idev, abs, re);
> +}
> +
> +static int virtinput_init_vqs(struct virtio_input *vi)
> +{
> + struct virtqueue *vqs[2];
> + vq_callback_t *cbs[] = { virtinput_recv_events,
> + virtinput_recv_status };
> + static const char * names[] = { "events", "status" };
No space between * and names expected
> + 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]);
> + virtqueue_kick(vi->evt);
> +
> + return 0;
> +}
> +
> +static int virtinput_probe(struct virtio_device *vdev)
> +{
> + struct virtio_input *vi;
> + size_t size;
> + int abs, err;
> +
> + if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1))
> + return -ENODEV;
> +
> + vi = kzalloc(sizeof(*vi), GFP_KERNEL);
> + if (!vi)
> + return -ENOMEM;
> +
> + vdev->priv = vi;
> + vi->vdev = vdev;
> + spin_lock_init(&vi->lock);
> +
> + err = virtinput_init_vqs(vi);
> + if (err)
> + goto err_init_vq;
> +
> + vi->idev = input_allocate_device();
> + if (!vi->idev) {
> + err = -ENOMEM;
> + goto err_input_alloc;
> + }
> + 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);
> + vi->idev->name = vi->name;
> + vi->idev->phys = vi->phys;
> + vi->idev->uniq = vi->serial;
> +
> + size = virtinput_cfg_select(vi, VIRTIO_INPUT_CFG_ID_DEVIDS, 0);
> + if (size >= 8) {
What does 8 mean here? Should be sizeof virtio_input_devids?
> + virtio_cread(vi->vdev, struct virtio_input_config,
> + u.ids.bustype, &vi->idev->id.bustype);
> + virtio_cread(vi->vdev, struct virtio_input_config,
> + u.ids.vendor, &vi->idev->id.vendor);
> + virtio_cread(vi->vdev, struct virtio_input_config,
> + u.ids.product, &vi->idev->id.product);
> + virtio_cread(vi->vdev, struct virtio_input_config,
> + u.ids.version, &vi->idev->id.version);
> + } else {
> + vi->idev->id.bustype = BUS_VIRTUAL;
> + }
> +
> + 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->dev.parent = &vdev->dev;
> + 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);
> + }
> + }
> + virtio_device_ready(vdev);
> +
At this point you can already get interrupts.
This will cause events to be forwarded.
I'm guessing this is ok since you called
input_allocate_device, but worth checking,
and maybe adding a comment.
> + err = input_register_device(vi->idev);
> + if (err)
> + goto err_input_register;
> +
> + return 0;
> +
> +err_input_register:
> + input_free_device(vi->idev);
At this point you can already get interrupts
since you called virtio_device_ready, and
getting events from a freed device likely won't
DTRT.
> +err_input_alloc:
> + vdev->config->del_vqs(vdev);
> +err_init_vq:
> + kfree(vi);
> + return err;
> +}
> +
> +static void virtinput_remove(struct virtio_device *vdev)
> +{
> + struct virtio_input *vi = vdev->priv;
> +
> + input_unregister_device(vi->idev);
same thing here, you might get an event at this point.
You need to somehow block new events
being sent to device while keeping
device around.
Since you already do everything under a spinlock,
it's probably easiest to add a flag discarding
recv events. You can then check it in virtinput_recv_events
before calling input_event.
> + vdev->config->del_vqs(vdev);
> + kfree(vi);
> +}
> +
> +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,
I note this driver doesn't seem to handle hybernation,
that's probably a bug?
> +};
> +
> +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@redhat.com>");
> diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild
> index 68ceb97..04b829e 100644
> --- a/include/uapi/linux/Kbuild
> +++ b/include/uapi/linux/Kbuild
> @@ -430,6 +430,7 @@ header-y += virtio_blk.h
> header-y += virtio_config.h
> header-y += virtio_console.h
> header-y += virtio_ids.h
> +header-y += virtio_input.h
> header-y += virtio_net.h
> header-y += virtio_pci.h
> header-y += virtio_ring.h
> 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..7fceabd
> --- /dev/null
> +++ b/include/uapi/linux/virtio_input.h
> @@ -0,0 +1,76 @@
> +#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_ID_DEVIDS = 0x03,
> + VIRTIO_INPUT_CFG_PROP_BITS = 0x10,
> + VIRTIO_INPUT_CFG_EV_BITS = 0x11,
> + VIRTIO_INPUT_CFG_ABS_INFO = 0x12,
> +};
> +
> +struct virtio_input_absinfo {
> + __virtio32 min;
> + __virtio32 max;
> + __virtio32 fuzz;
> + __virtio32 flat;
> + __virtio32 res;
> +};
> +
> +struct virtio_input_devids {
> + __virtio16 bustype;
> + __virtio16 vendor;
> + __virtio16 product;
> + __virtio16 version;
> +};
> +
this padding bt two spaces looks weird.
> +struct virtio_input_config {
> + __u8 select;
> + __u8 subsel;
> + __u8 size;
> + __u8 reserved;
> + union {
> + char string[128];
> + __u8 bitmap[128];
I note that neither string nor bitmap are used by
driver. What are they in aid of?
> + struct virtio_input_absinfo abs;
> + struct virtio_input_devids ids;
> + } u;
> +};
> +
> +struct virtio_input_event {
> + __le16 type;
> + __le16 code;
> + __le32 value;
> +};
> +
> +#endif /* _LINUX_VIRTIO_INPUT_H */
> --
> 1.8.3.1
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