Re: [Qemu-devel] [PATCH qemu 6/6] virtio-input: evdev passthrough

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Apr 10, 2014 at 11:07:54AM +0200, Gerd Hoffmann wrote:
> This allows to assign host input devices to the guest:
> 
> qemu -device virto-input-host-pci,evdev=/dev/input/event<nr>
> 
> The guest gets exclusive access to the input device, so be careful
> with assigning the keyboard if you have only one connected to your
> machine.
> 
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  hw/input/Makefile.objs           |   1 +
>  hw/input/virtio-input-host.c     | 174 +++++++++++++++++++++++++++++++++++++++
>  hw/virtio/virtio-pci.c           |  31 +++++++
>  hw/virtio/virtio-pci.h           |  10 +++
>  include/hw/virtio/virtio-input.h |  13 +++
>  5 files changed, 229 insertions(+)
>  create mode 100644 hw/input/virtio-input-host.c
> 
> diff --git a/hw/input/Makefile.objs b/hw/input/Makefile.objs
> index 0179154..9461b37 100644
> --- a/hw/input/Makefile.objs
> +++ b/hw/input/Makefile.objs
> @@ -12,6 +12,7 @@ ifeq ($(CONFIG_LINUX),y)
>  common-obj-$(CONFIG_VIRTIO) += virtio-input.o
>  common-obj-$(CONFIG_VIRTIO) += virtio-input-hid.o
>  common-obj-$(CONFIG_VIRTIO) += virtio-input-control.o
> +common-obj-$(CONFIG_VIRTIO) += virtio-input-host.o
>  endif
>  
>  obj-$(CONFIG_MILKYMIST) += milkymist-softusb.o
> diff --git a/hw/input/virtio-input-host.c b/hw/input/virtio-input-host.c
> new file mode 100644
> index 0000000..663d967
> --- /dev/null
> +++ b/hw/input/virtio-input-host.c
> @@ -0,0 +1,174 @@
> +/*
> + * This work is licensed under the terms of the GNU GPL, version 2 or
> + * (at your option) any later version.  See the COPYING file in the
> + * top-level directory.
> + */
> +
> +#include "qemu-common.h"
> +#include "qemu/sockets.h"
> +
> +#include "hw/qdev.h"
> +#include "hw/virtio/virtio.h"
> +#include "hw/virtio/virtio-input.h"
> +
> +#include "ui/console.h"
> +
> +#include <linux/input.h>
> +
> +/* ----------------------------------------------------------------- */
> +
> +static struct virtio_input_config virtio_input_host_config[] = {
> +    { /* empty list */ },
> +};
> +
> +static void virtio_input_host_event(void *opaque)
> +{
> +    VirtIOInputHost *vhost = opaque;

I'd prefer a name that does not imply
vhost infrastructure - which is an out of process QEMU backend
(kernel or another userspace process) accessing guest
memory directly.
This one is completely in-process.

> +    VirtIOInput *vinput = VIRTIO_INPUT(vhost);
> +    struct virtio_input_event virtio;
> +    struct input_event evdev;
> +    bool notify = false;
> +    int rc;
> +
> +    for (;;) {

You might want to limit this, requeue if there's
a storm of events.

> +        rc = read(vhost->fd, &evdev, sizeof(evdev));
> +        if (rc != sizeof(evdev)) {
> +            break;
> +        }
> +
> +        virtio.type  = cpu_to_le16(evdev.type);
> +        virtio.code  = cpu_to_le16(evdev.code);
> +        virtio.value = cpu_to_le32(evdev.value);
> +        virtio_input_send(vinput, &virtio);
> +
> +        if (evdev.type == EV_SYN) {
> +            notify = true;
> +        }
> +    }
> +
> +    if (notify) {
> +        virtio_notify(VIRTIO_DEVICE(vhost), vinput->evt);
> +    }
> +}
> +
> +static void virtio_input_bits_config(VirtIOInputHost *vhost,
> +                                     int type, int count)
> +{
> +    virtio_input_config bits;
> +    int rc, i, size = 0;
> +
> +    memset(&bits, 0, sizeof(bits));
> +    rc = ioctl(vhost->fd, EVIOCGBIT(type, count/8), bits.u.bitmap);
> +    if (rc < 0) {
> +        return;
> +    }
> +
> +    for (i = 0; i < count/8; i++) {
> +        if (bits.u.bitmap[i]) {
> +            size = i+1;
> +        }
> +    }
> +    if (size == 0) {
> +        return;
> +    }
> +
> +    bits.select = VIRTIO_INPUT_CFG_EV_BITS;
> +    bits.subsel = type;
> +    bits.size   = size;
> +    virtio_input_add_config(VIRTIO_INPUT(vhost), &bits);
> +}
> +
> +static void virtio_input_host_realize(DeviceState *dev, Error **errp)
> +{
> +    VirtIOInputHost *vhost = VIRTIO_INPUT_HOST(dev);
> +    VirtIOInput *vinput = VIRTIO_INPUT(dev);
> +    virtio_input_config id;
> +    int rc, ver;
> +
> +    if (!vhost->evdev) {
> +        error_setg(errp, "evdev property is required");
> +        return;
> +    }
> +
> +    vhost->fd = open(vhost->evdev, O_RDWR);
> +    if (vhost->fd < 0)  {
> +        error_setg_file_open(errp, errno, vhost->evdev);
> +        return;
> +    }
> +    qemu_set_nonblock(vhost->fd);
> +
> +    rc = ioctl(vhost->fd, EVIOCGVERSION, &ver);
> +    if (rc < 0) {
> +        error_setg(errp, "%s: is not an evdev device", vhost->evdev);
> +        goto err_close;
> +    }

Hmm is that all?
Don't we want to report versioning info to guests?


> +
> +    rc = ioctl(vhost->fd, EVIOCGRAB, 1);
> +    if (rc < 0) {
> +        error_setg_errno(errp, errno, "%s: failed to get exclusive access",
> +                         vhost->evdev);
> +        goto err_close;
> +    }
> +
> +    memset(&id, 0, sizeof(id));
> +    ioctl(vhost->fd, EVIOCGNAME(sizeof(id.u.string)-1), id.u.string);
> +    id.select = VIRTIO_INPUT_CFG_ID_NAME;
> +    id.size = strlen(id.u.string);
> +    virtio_input_add_config(vinput, &id);
> +
> +    virtio_input_bits_config(vhost, EV_KEY, KEY_CNT);
> +    virtio_input_bits_config(vhost, EV_REL, REL_CNT);
> +    virtio_input_bits_config(vhost, EV_ABS, ABS_CNT);
> +    virtio_input_bits_config(vhost, EV_MSC, MSC_CNT);
> +    virtio_input_bits_config(vhost, EV_SW,  SW_CNT);
> +
> +    qemu_set_fd_handler(vhost->fd, virtio_input_host_event, NULL, vhost);
> +    return;
> +
> +err_close:
> +    close(vhost->fd);
> +    vhost->fd = -1;
> +    return;
> +}
> +
> +static void virtio_input_host_unrealize(DeviceState *dev, Error **errp)
> +{
> +    VirtIOInputHost *vhost = VIRTIO_INPUT_HOST(dev);
> +
> +    if (vhost->fd > 0) {
> +        qemu_set_fd_handler(vhost->fd, NULL, NULL, NULL);
> +        close(vhost->fd);
> +    }
> +}
> +
> +static void virtio_input_host_class_init(ObjectClass *klass, void *data)
> +{
> +    VirtIOInputClass *vic = VIRTIO_INPUT_CLASS(klass);
> +
> +    vic->realize       = virtio_input_host_realize;
> +    vic->unrealize     = virtio_input_host_unrealize;
> +}
> +
> +static void virtio_input_host_init(Object *obj)
> +{
> +    VirtIOInput *vinput = VIRTIO_INPUT(obj);
> +
> +    virtio_input_init_config(vinput, virtio_input_host_config);
> +}
> +
> +static const TypeInfo virtio_input_host_info = {
> +    .name          = TYPE_VIRTIO_INPUT_HOST,
> +    .parent        = TYPE_VIRTIO_INPUT,
> +    .instance_size = sizeof(VirtIOInputHost),
> +    .instance_init = virtio_input_host_init,
> +    .class_init    = virtio_input_host_class_init,
> +};
> +
> +/* ----------------------------------------------------------------- */
> +
> +static void virtio_register_types(void)
> +{
> +    type_register_static(&virtio_input_host_info);
> +}
> +
> +type_init(virtio_register_types)
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 9446d45..9f81fc0 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -1547,6 +1547,14 @@ static Property virtio_input_ctrl_pci_properties[] = {
>      DEFINE_PROP_END_OF_LIST(),
>  };
>  
> +static Property virtio_input_host_pci_properties[] = {
> +    DEFINE_VIRTIO_COMMON_FEATURES(VirtIOPCIProxy, host_features),
> +    DEFINE_VIRTIO_INPUT_PROPERTIES(VirtIOInputPCI, vdev.input),
> +    DEFINE_PROP_STRING("evdev", VirtIOInputHostPCI, vdev.evdev),
> +    DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 2),
> +    DEFINE_PROP_END_OF_LIST(),
> +};
> +
>  static int virtio_input_pci_init(VirtIOPCIProxy *vpci_dev)
>  {
>      VirtIOInputPCI *vinput = VIRTIO_INPUT_PCI(vpci_dev);
> @@ -1585,6 +1593,13 @@ static void virtio_input_ctrl_pci_class_init(ObjectClass *klass, void *data)
>      dc->props = virtio_input_ctrl_pci_properties;
>  }
>  
> +static void virtio_input_host_pci_class_init(ObjectClass *klass, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +
> +    dc->props = virtio_input_host_pci_properties;
> +}
> +
>  static void virtio_keyboard_initfn(Object *obj)
>  {
>      VirtIOInputHIDPCI *dev = VIRTIO_INPUT_HID_PCI(obj);
> @@ -1613,6 +1628,13 @@ static void virtio_ctrl_initfn(Object *obj)
>      object_property_add_child(obj, "virtio-backend", OBJECT(&dev->vdev), NULL);
>  }
>  
> +static void virtio_host_initfn(Object *obj)
> +{
> +    VirtIOInputHostPCI *dev = VIRTIO_INPUT_HOST_PCI(obj);
> +    object_initialize(&dev->vdev, sizeof(dev->vdev), TYPE_VIRTIO_INPUT_HOST);
> +    object_property_add_child(obj, "virtio-backend", OBJECT(&dev->vdev), NULL);
> +}
> +
>  static const TypeInfo virtio_input_pci_info = {
>      .name          = TYPE_VIRTIO_INPUT_PCI,
>      .parent        = TYPE_VIRTIO_PCI,
> @@ -1658,6 +1680,14 @@ static const TypeInfo virtio_ctrl_pci_info = {
>      .class_init    = virtio_input_ctrl_pci_class_init,
>  };
>  
> +static const TypeInfo virtio_host_pci_info = {
> +    .name          = TYPE_VIRTIO_INPUT_HOST_PCI,
> +    .parent        = TYPE_VIRTIO_INPUT_PCI,
> +    .instance_size = sizeof(VirtIOInputHostPCI),
> +    .instance_init = virtio_host_initfn,
> +    .class_init    = virtio_input_host_pci_class_init,
> +};
> +
>  /* virtio-pci-bus */
>  
>  static void virtio_pci_bus_new(VirtioBusState *bus, size_t bus_size,
> @@ -1708,6 +1738,7 @@ static void virtio_pci_register_types(void)
>      type_register_static(&virtio_mouse_pci_info);
>      type_register_static(&virtio_tablet_pci_info);
>      type_register_static(&virtio_ctrl_pci_info);
> +    type_register_static(&virtio_host_pci_info);
>      type_register_static(&virtio_pci_bus_info);
>      type_register_static(&virtio_pci_info);
>  #ifdef CONFIG_VIRTFS
> diff --git a/hw/virtio/virtio-pci.h b/hw/virtio/virtio-pci.h
> index 0c26e64..4c12770 100644
> --- a/hw/virtio/virtio-pci.h
> +++ b/hw/virtio/virtio-pci.h
> @@ -43,6 +43,7 @@ typedef struct VirtIORngPCI VirtIORngPCI;
>  typedef struct VirtIOInputPCI VirtIOInputPCI;
>  typedef struct VirtIOInputHIDPCI VirtIOInputHIDPCI;
>  typedef struct VirtIOInputCtrlPCI VirtIOInputCtrlPCI;
> +typedef struct VirtIOInputHostPCI VirtIOInputHostPCI;
>  
>  /* virtio-pci-bus */
>  
> @@ -236,6 +237,15 @@ struct VirtIOInputCtrlPCI {
>      VirtIOInputCtrl vdev;
>  };
>  
> +#define TYPE_VIRTIO_INPUT_HOST_PCI "virtio-input-host-pci"
> +#define VIRTIO_INPUT_HOST_PCI(obj) \
> +        OBJECT_CHECK(VirtIOInputHostPCI, (obj), TYPE_VIRTIO_INPUT_HOST_PCI)
> +
> +struct VirtIOInputHostPCI {
> +    VirtIOPCIProxy parent_obj;
> +    VirtIOInputHost vdev;
> +};
> +
>  /* Virtio ABI version, if we increment this, we break the guest driver. */
>  #define VIRTIO_PCI_ABI_VERSION          0
>  
> diff --git a/include/hw/virtio/virtio-input.h b/include/hw/virtio/virtio-input.h
> index d753834..94ea405 100644
> --- a/include/hw/virtio/virtio-input.h
> +++ b/include/hw/virtio/virtio-input.h
> @@ -73,6 +73,12 @@ typedef struct virtio_input_event {
>  #define VIRTIO_INPUT_CTRL_GET_PARENT_CLASS(obj) \
>          OBJECT_GET_PARENT_CLASS(obj, TYPE_VIRTIO_INPUT_CTRL)
>  
> +#define TYPE_VIRTIO_INPUT_HOST   "virtio-input-host"
> +#define VIRTIO_INPUT_HOST(obj) \
> +        OBJECT_CHECK(VirtIOInputHost, (obj), TYPE_VIRTIO_INPUT_HOST)
> +#define VIRTIO_INPUT_HOST_GET_PARENT_CLASS(obj) \
> +        OBJECT_GET_PARENT_CLASS(obj, TYPE_VIRTIO_INPUT_HOST)
> +
>  #define DEFINE_VIRTIO_INPUT_PROPERTIES(_state, _field)       \
>          DEFINE_PROP_STRING("serial", _state, _field.serial), \
>          DEFINE_PROP_STRING("seat", _state, _field.seat)
> @@ -82,6 +88,7 @@ typedef struct VirtIOInputClass VirtIOInputClass;
>  typedef struct VirtIOInputConfig VirtIOInputConfig;
>  typedef struct VirtIOInputHID VirtIOInputHID;
>  typedef struct VirtIOInputCtrl VirtIOInputCtrl;
> +typedef struct VirtIOInputHost VirtIOInputHost;
>  
>  struct virtio_input_conf {
>      char *serial;
> @@ -128,6 +135,12 @@ struct VirtIOInputCtrl {
>      Notifier                          powerdown;
>  };
>  
> +struct VirtIOInputHost {
> +    VirtIOInput                       parent_obj;
> +    char                              *evdev;
> +    int                               fd;
> +};
> +
>  void virtio_input_send(VirtIOInput *vinput, virtio_input_event *event);
>  void virtio_input_init_config(VirtIOInput *vinput,
>                                virtio_input_config *config);
> -- 
> 1.8.3.1