diff mbox series

[1/5] hw/virtio: add boilerplate for vhost-user-i2c device

Message ID 680d46df15a19a7ccb05f79370cb03226c23d943.1616570702.git.viresh.kumar@linaro.org (mailing list archive)
State New, archived
Headers show
Series virtio: Implement generic vhost-user-i2c backend | expand

Commit Message

Viresh Kumar March 24, 2021, 7:33 a.m. UTC 
This creates the QEMU side of the vhost-user-i2c device which connects
to the remote daemon. It is based of vhost-user-fs code.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 hw/virtio/Kconfig                           |   5 +
 hw/virtio/meson.build                       |   1 +
 hw/virtio/vhost-user-i2c.c                  | 286 ++++++++++++++++++++
 include/hw/virtio/vhost-user-i2c.h          |  37 +++
 include/standard-headers/linux/virtio_ids.h |   1 +
 5 files changed, 330 insertions(+)
 create mode 100644 hw/virtio/vhost-user-i2c.c
 create mode 100644 include/hw/virtio/vhost-user-i2c.h

Comments

Alex Bennée March 29, 2021, 3:13 p.m. UTC | #1 
Viresh Kumar <viresh.kumar@linaro.org> writes:

> This creates the QEMU side of the vhost-user-i2c device which connects
> to the remote daemon. It is based of vhost-user-fs code.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
>  hw/virtio/Kconfig                           |   5 +
>  hw/virtio/meson.build                       |   1 +
>  hw/virtio/vhost-user-i2c.c                  | 286 ++++++++++++++++++++
>  include/hw/virtio/vhost-user-i2c.h          |  37 +++
>  include/standard-headers/linux/virtio_ids.h |   1 +
>  5 files changed, 330 insertions(+)
>  create mode 100644 hw/virtio/vhost-user-i2c.c
>  create mode 100644 include/hw/virtio/vhost-user-i2c.h
>
> diff --git a/hw/virtio/Kconfig b/hw/virtio/Kconfig
> index 0eda25c4e1bf..35ab45e2095c 100644
> --- a/hw/virtio/Kconfig
> +++ b/hw/virtio/Kconfig
> @@ -58,3 +58,8 @@ config VIRTIO_MEM
>      depends on LINUX
>      depends on VIRTIO_MEM_SUPPORTED
>      select MEM_DEVICE
> +
> +config VHOST_USER_I2C
> +    bool
> +    default y
> +    depends on VIRTIO && VHOST_USER
> diff --git a/hw/virtio/meson.build b/hw/virtio/meson.build
> index fbff9bc9d4de..1a0d736a0db5 100644
> --- a/hw/virtio/meson.build
> +++ b/hw/virtio/meson.build
> @@ -25,6 +25,7 @@ virtio_ss.add(when: 'CONFIG_VHOST_USER_VSOCK', if_true: files('vhost-user-vsock.
>  virtio_ss.add(when: 'CONFIG_VIRTIO_RNG', if_true: files('virtio-rng.c'))
>  virtio_ss.add(when: 'CONFIG_VIRTIO_IOMMU', if_true: files('virtio-iommu.c'))
>  virtio_ss.add(when: 'CONFIG_VIRTIO_MEM', if_true: files('virtio-mem.c'))
> +virtio_ss.add(when: 'CONFIG_VHOST_USER_I2C', if_true: files('vhost-user-i2c.c'))
>  
>  virtio_pci_ss = ss.source_set()
>  virtio_pci_ss.add(when: 'CONFIG_VHOST_VSOCK', if_true: files('vhost-vsock-pci.c'))
> diff --git a/hw/virtio/vhost-user-i2c.c b/hw/virtio/vhost-user-i2c.c
> new file mode 100644
> index 000000000000..7b0dc24412a4
> --- /dev/null
> +++ b/hw/virtio/vhost-user-i2c.c
> @@ -0,0 +1,286 @@
> +/*
> + * Vhost-user i2c virtio device
> + *
> + * Copyright (c) 2021 Viresh Kumar <viresh.kumar@linaro.org>
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qapi/error.h"
> +#include "hw/qdev-properties.h"
> +#include "hw/virtio/virtio-bus.h"
> +#include "hw/virtio/vhost-user-i2c.h"
> +#include "qemu/error-report.h"
> +#include "standard-headers/linux/virtio_ids.h"
> +
> +static void vu_i2c_start(VirtIODevice *vdev)
> +{
> +    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
> +    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
> +    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
> +    int ret;
> +    int i;
> +
> +    if (!k->set_guest_notifiers) {
> +        error_report("binding does not support guest notifiers");
> +        return;
> +    }
> +
> +    ret = vhost_dev_enable_notifiers(&i2c->vhost_dev, vdev);
> +    if (ret < 0) {
> +        error_report("Error enabling host notifiers: %d", -ret);
> +        return;
> +    }
> +
> +    ret = k->set_guest_notifiers(qbus->parent, i2c->vhost_dev.nvqs, true);
> +    if (ret < 0) {
> +        error_report("Error binding guest notifier: %d", -ret);
> +        goto err_host_notifiers;
> +    }
> +
> +    i2c->vhost_dev.acked_features = vdev->guest_features;
> +    ret = vhost_dev_start(&i2c->vhost_dev, vdev);
> +    if (ret < 0) {
> +        error_report("Error starting vhost-user-i2c: %d", -ret);
> +        goto err_guest_notifiers;
> +    }
> +
> +    /*
> +     * guest_notifier_mask/pending not used yet, so just unmask
> +     * everything here. virtio-pci will do the right thing by
> +     * enabling/disabling irqfd.
> +     */
> +    for (i = 0; i < i2c->vhost_dev.nvqs; i++) {
> +        vhost_virtqueue_mask(&i2c->vhost_dev, vdev, i, false);
> +    }
> +
> +    return;
> +
> +err_guest_notifiers:
> +    k->set_guest_notifiers(qbus->parent, i2c->vhost_dev.nvqs, false);
> +err_host_notifiers:
> +    vhost_dev_disable_notifiers(&i2c->vhost_dev, vdev);
> +}
> +
> +static void vu_i2c_stop(VirtIODevice *vdev)
> +{
> +    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
> +    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
> +    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
> +    int ret;
> +
> +    if (!k->set_guest_notifiers) {
> +        return;
> +    }
> +
> +    vhost_dev_stop(&i2c->vhost_dev, vdev);
> +
> +    ret = k->set_guest_notifiers(qbus->parent, i2c->vhost_dev.nvqs, false);
> +    if (ret < 0) {
> +        error_report("vhost guest notifier cleanup failed: %d", ret);
> +        return;
> +    }
> +
> +    vhost_dev_disable_notifiers(&i2c->vhost_dev, vdev);
> +}
> +
> +static void vu_i2c_set_status(VirtIODevice *vdev, uint8_t status)
> +{
> +    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
> +    bool should_start = status & VIRTIO_CONFIG_S_DRIVER_OK;
> +
> +    if (!vdev->vm_running) {
> +        should_start = false;
> +    }
> +
> +    if (i2c->vhost_dev.started == should_start) {
> +        return;
> +    }
> +
> +    if (should_start) {
> +        vu_i2c_start(vdev);
> +    } else {
> +        vu_i2c_stop(vdev);
> +    }
> +}
> +
> +static uint64_t vu_i2c_get_features(VirtIODevice *vdev,
> +                                    uint64_t requested_features, Error **errp)
> +{
> +    /* No feature bits used yet */
> +    return requested_features;
> +}
> +
> +static void vu_i2c_handle_output(VirtIODevice *vdev, VirtQueue *vq)
> +{
> +    /*
> +     * Not normally called; it's the daemon that handles the queue;
> +     * however virtio's cleanup path can call this.
> +     */
> +}
> +
> +static void vu_i2c_guest_notifier_mask(VirtIODevice *vdev, int idx, bool mask)
> +{
> +    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
> +
> +    vhost_virtqueue_mask(&i2c->vhost_dev, vdev, idx, mask);
> +}
> +
> +static bool vu_i2c_guest_notifier_pending(VirtIODevice *vdev, int idx)
> +{
> +    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
> +
> +    return vhost_virtqueue_pending(&i2c->vhost_dev, idx);
> +}
> +
> +static void do_vhost_user_cleanup(VirtIODevice *vdev, VHostUserI2C *i2c)
> +{
> +    vhost_user_cleanup(&i2c->vhost_user);
> +    virtio_delete_queue(i2c->req_vq);
> +    g_free(i2c->vhost_dev.vqs);
> +    virtio_cleanup(vdev);
> +    g_free(i2c->vhost_dev.vqs);

This is a double free of the same queue.

> +    i2c->vhost_dev.vqs = NULL;
> +}
> +
> +static int vu_i2c_connect(DeviceState *dev)
> +{
> +    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
> +    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
> +
> +    if (i2c->connected) {
> +        return 0;
> +    }
> +    i2c->connected = true;
> +
> +    /* restore vhost state */
> +    if (virtio_device_started(vdev, vdev->status)) {
> +        vu_i2c_start(vdev);
> +    }
> +
> +    return 0;
> +}
> +
> +static void vu_i2c_disconnect(DeviceState *dev)
> +{
> +    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
> +    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
> +
> +    if (!i2c->connected) {
> +        return;
> +    }
> +    i2c->connected = false;
> +
> +    if (i2c->vhost_dev.started) {
> +        vu_i2c_stop(vdev);
> +    }
> +}
> +
> +static void vu_i2c_event(void *opaque, QEMUChrEvent event)
> +{
> +    DeviceState *dev = opaque;
> +    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
> +    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
> +
> +    switch (event) {
> +    case CHR_EVENT_OPENED:
> +        if (vu_i2c_connect(dev) < 0) {
> +            qemu_chr_fe_disconnect(&i2c->conf.chardev);
> +            return;
> +        }
> +        break;
> +    case CHR_EVENT_CLOSED:
> +        vu_i2c_disconnect(dev);
> +        break;
> +    case CHR_EVENT_BREAK:
> +    case CHR_EVENT_MUX_IN:
> +    case CHR_EVENT_MUX_OUT:
> +        /* Ignore */
> +        break;
> +    }
> +}
> +
> +static void vu_i2c_device_realize(DeviceState *dev, Error **errp)
> +{
> +    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
> +    VHostUserI2C *i2c = VHOST_USER_I2C(dev);
> +    int ret;
> +
> +    if (!i2c->conf.chardev.chr) {
> +        error_setg(errp, "missing chardev");
> +        return;
> +    }
> +
> +    if (!vhost_user_init(&i2c->vhost_user, &i2c->conf.chardev, errp)) {
> +        return;
> +    }
> +
> +    virtio_init(vdev, "vhost-user-i2c", VIRTIO_ID_I2C, 0);
> +
> +    i2c->req_vq = virtio_add_queue(vdev, 3, vu_i2c_handle_output);
> +    i2c->vhost_dev.nvqs = 1;
> +    i2c->vhost_dev.vqs = g_new0(struct vhost_virtqueue, i2c->vhost_dev.nvqs);
> +    ret = vhost_dev_init(&i2c->vhost_dev, &i2c->vhost_user,
> +                         VHOST_BACKEND_TYPE_USER, 0);
> +    if (ret < 0) {
> +        error_setg_errno(errp, -ret, "vhost_dev_init() failed");
> +        do_vhost_user_cleanup(vdev, i2c);
> +    }
> +
> +    qemu_chr_fe_set_handlers(&i2c->conf.chardev, NULL, NULL, vu_i2c_event, NULL,
> +                             dev, NULL, true);
> +}
> +
> +static void vu_i2c_device_unrealize(DeviceState *dev)
> +{
> +    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
> +    VHostUserI2C *i2c = VHOST_USER_I2C(dev);
> +
> +    /* This will stop vhost backend if appropriate. */
> +    vu_i2c_set_status(vdev, 0);
> +
> +    vhost_dev_cleanup(&i2c->vhost_dev);
> +
> +    do_vhost_user_cleanup(vdev, i2c);
> +}
> +
> +static const VMStateDescription vu_i2c_vmstate = {
> +    .name = "vhost-user-i2c",
> +    .unmigratable = 1,
> +};
> +
> +static Property vu_i2c_properties[] = {
> +    DEFINE_PROP_CHR("chardev", VHostUserI2C, conf.chardev),
> +    DEFINE_PROP_END_OF_LIST(),
> +};
> +
> +static void vu_i2c_class_init(ObjectClass *klass, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +    VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
> +
> +    device_class_set_props(dc, vu_i2c_properties);
> +    dc->vmsd = &vu_i2c_vmstate;
> +    set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
> +    vdc->realize = vu_i2c_device_realize;
> +    vdc->unrealize = vu_i2c_device_unrealize;
> +    vdc->get_features = vu_i2c_get_features;
> +    vdc->set_status = vu_i2c_set_status;
> +    vdc->guest_notifier_mask = vu_i2c_guest_notifier_mask;
> +    vdc->guest_notifier_pending = vu_i2c_guest_notifier_pending;
> +}
> +
> +static const TypeInfo vu_i2c_info = {
> +    .name = TYPE_VHOST_USER_I2C,
> +    .parent = TYPE_VIRTIO_DEVICE,
> +    .instance_size = sizeof(VHostUserI2C),
> +    .class_init = vu_i2c_class_init,
> +};
> +
> +static void vu_i2c_register_types(void)
> +{
> +    type_register_static(&vu_i2c_info);
> +}
> +
> +type_init(vu_i2c_register_types)
> diff --git a/include/hw/virtio/vhost-user-i2c.h b/include/hw/virtio/vhost-user-i2c.h
> new file mode 100644
> index 000000000000..a5fffcb6096c
> --- /dev/null
> +++ b/include/hw/virtio/vhost-user-i2c.h
> @@ -0,0 +1,37 @@
> +/*
> + * Vhost-user i2c virtio device
> + *
> + * Copyright (c) 2021 Viresh Kumar <viresh.kumar@linaro.org>
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + */
> +
> +#ifndef _QEMU_VHOST_USER_I2C_H
> +#define _QEMU_VHOST_USER_I2C_H
> +
> +#include "hw/virtio/virtio.h"
> +#include "hw/virtio/vhost.h"
> +#include "hw/virtio/vhost-user.h"
> +#include "chardev/char-fe.h"
> +
> +#define TYPE_VHOST_USER_I2C "vhost-user-i2c-device"
> +OBJECT_DECLARE_SIMPLE_TYPE(VHostUserI2C, VHOST_USER_I2C)
> +
> +typedef struct {
> +    CharBackend chardev;
> +} VHostUserI2CConf;
> +
> +struct VHostUserI2C {
> +    /*< private >*/
> +    VirtIODevice parent;
> +    VHostUserI2CConf conf;
> +    struct vhost_virtqueue *vhost_vq;
> +    struct vhost_dev vhost_dev;
> +    VhostUserState vhost_user;
> +    VirtQueue *req_vq;
> +    bool connected;
> +
> +    /*< public >*/
> +};
> +
> +#endif /* _QEMU_VHOST_USER_I2C_H */
> diff --git a/include/standard-headers/linux/virtio_ids.h b/include/standard-headers/linux/virtio_ids.h
> index bc1c0621f5ed..aba00c54b9cd 100644
> --- a/include/standard-headers/linux/virtio_ids.h
> +++ b/include/standard-headers/linux/virtio_ids.h
> @@ -54,5 +54,6 @@
>  #define VIRTIO_ID_FS			26 /* virtio filesystem */
>  #define VIRTIO_ID_PMEM			27 /* virtio pmem */
>  #define VIRTIO_ID_MAC80211_HWSIM	29 /* virtio mac80211-hwsim */
> +#define VIRTIO_ID_I2C			34 /* virtio i2c */

This should come in as a separate patch. Generally I run:

  ./scripts/update-linux-headers.sh ~/lsrc/linux.git

and tag the patch as (!MERGE) as a place holder until it can get picked
up with one of the regular UAPI updates.

>  
>  #endif /* _LINUX_VIRTIO_IDS_H */
diff mbox series

Patch

diff --git a/hw/virtio/Kconfig b/hw/virtio/Kconfig
index 0eda25c4e1bf..35ab45e2095c 100644
--- a/hw/virtio/Kconfig
+++ b/hw/virtio/Kconfig
@@ -58,3 +58,8 @@  config VIRTIO_MEM
     depends on LINUX
     depends on VIRTIO_MEM_SUPPORTED
     select MEM_DEVICE
+
+config VHOST_USER_I2C
+    bool
+    default y
+    depends on VIRTIO && VHOST_USER
diff --git a/hw/virtio/meson.build b/hw/virtio/meson.build
index fbff9bc9d4de..1a0d736a0db5 100644
--- a/hw/virtio/meson.build
+++ b/hw/virtio/meson.build
@@ -25,6 +25,7 @@  virtio_ss.add(when: 'CONFIG_VHOST_USER_VSOCK', if_true: files('vhost-user-vsock.
 virtio_ss.add(when: 'CONFIG_VIRTIO_RNG', if_true: files('virtio-rng.c'))
 virtio_ss.add(when: 'CONFIG_VIRTIO_IOMMU', if_true: files('virtio-iommu.c'))
 virtio_ss.add(when: 'CONFIG_VIRTIO_MEM', if_true: files('virtio-mem.c'))
+virtio_ss.add(when: 'CONFIG_VHOST_USER_I2C', if_true: files('vhost-user-i2c.c'))
 
 virtio_pci_ss = ss.source_set()
 virtio_pci_ss.add(when: 'CONFIG_VHOST_VSOCK', if_true: files('vhost-vsock-pci.c'))
diff --git a/hw/virtio/vhost-user-i2c.c b/hw/virtio/vhost-user-i2c.c
new file mode 100644
index 000000000000..7b0dc24412a4
--- /dev/null
+++ b/hw/virtio/vhost-user-i2c.c
@@ -0,0 +1,286 @@ 
+/*
+ * Vhost-user i2c virtio device
+ *
+ * Copyright (c) 2021 Viresh Kumar <viresh.kumar@linaro.org>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "hw/qdev-properties.h"
+#include "hw/virtio/virtio-bus.h"
+#include "hw/virtio/vhost-user-i2c.h"
+#include "qemu/error-report.h"
+#include "standard-headers/linux/virtio_ids.h"
+
+static void vu_i2c_start(VirtIODevice *vdev)
+{
+    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
+    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
+    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+    int ret;
+    int i;
+
+    if (!k->set_guest_notifiers) {
+        error_report("binding does not support guest notifiers");
+        return;
+    }
+
+    ret = vhost_dev_enable_notifiers(&i2c->vhost_dev, vdev);
+    if (ret < 0) {
+        error_report("Error enabling host notifiers: %d", -ret);
+        return;
+    }
+
+    ret = k->set_guest_notifiers(qbus->parent, i2c->vhost_dev.nvqs, true);
+    if (ret < 0) {
+        error_report("Error binding guest notifier: %d", -ret);
+        goto err_host_notifiers;
+    }
+
+    i2c->vhost_dev.acked_features = vdev->guest_features;
+    ret = vhost_dev_start(&i2c->vhost_dev, vdev);
+    if (ret < 0) {
+        error_report("Error starting vhost-user-i2c: %d", -ret);
+        goto err_guest_notifiers;
+    }
+
+    /*
+     * guest_notifier_mask/pending not used yet, so just unmask
+     * everything here. virtio-pci will do the right thing by
+     * enabling/disabling irqfd.
+     */
+    for (i = 0; i < i2c->vhost_dev.nvqs; i++) {
+        vhost_virtqueue_mask(&i2c->vhost_dev, vdev, i, false);
+    }
+
+    return;
+
+err_guest_notifiers:
+    k->set_guest_notifiers(qbus->parent, i2c->vhost_dev.nvqs, false);
+err_host_notifiers:
+    vhost_dev_disable_notifiers(&i2c->vhost_dev, vdev);
+}
+
+static void vu_i2c_stop(VirtIODevice *vdev)
+{
+    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
+    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
+    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+    int ret;
+
+    if (!k->set_guest_notifiers) {
+        return;
+    }
+
+    vhost_dev_stop(&i2c->vhost_dev, vdev);
+
+    ret = k->set_guest_notifiers(qbus->parent, i2c->vhost_dev.nvqs, false);
+    if (ret < 0) {
+        error_report("vhost guest notifier cleanup failed: %d", ret);
+        return;
+    }
+
+    vhost_dev_disable_notifiers(&i2c->vhost_dev, vdev);
+}
+
+static void vu_i2c_set_status(VirtIODevice *vdev, uint8_t status)
+{
+    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
+    bool should_start = status & VIRTIO_CONFIG_S_DRIVER_OK;
+
+    if (!vdev->vm_running) {
+        should_start = false;
+    }
+
+    if (i2c->vhost_dev.started == should_start) {
+        return;
+    }
+
+    if (should_start) {
+        vu_i2c_start(vdev);
+    } else {
+        vu_i2c_stop(vdev);
+    }
+}
+
+static uint64_t vu_i2c_get_features(VirtIODevice *vdev,
+                                    uint64_t requested_features, Error **errp)
+{
+    /* No feature bits used yet */
+    return requested_features;
+}
+
+static void vu_i2c_handle_output(VirtIODevice *vdev, VirtQueue *vq)
+{
+    /*
+     * Not normally called; it's the daemon that handles the queue;
+     * however virtio's cleanup path can call this.
+     */
+}
+
+static void vu_i2c_guest_notifier_mask(VirtIODevice *vdev, int idx, bool mask)
+{
+    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
+
+    vhost_virtqueue_mask(&i2c->vhost_dev, vdev, idx, mask);
+}
+
+static bool vu_i2c_guest_notifier_pending(VirtIODevice *vdev, int idx)
+{
+    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
+
+    return vhost_virtqueue_pending(&i2c->vhost_dev, idx);
+}
+
+static void do_vhost_user_cleanup(VirtIODevice *vdev, VHostUserI2C *i2c)
+{
+    vhost_user_cleanup(&i2c->vhost_user);
+    virtio_delete_queue(i2c->req_vq);
+    g_free(i2c->vhost_dev.vqs);
+    virtio_cleanup(vdev);
+    g_free(i2c->vhost_dev.vqs);
+    i2c->vhost_dev.vqs = NULL;
+}
+
+static int vu_i2c_connect(DeviceState *dev)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
+
+    if (i2c->connected) {
+        return 0;
+    }
+    i2c->connected = true;
+
+    /* restore vhost state */
+    if (virtio_device_started(vdev, vdev->status)) {
+        vu_i2c_start(vdev);
+    }
+
+    return 0;
+}
+
+static void vu_i2c_disconnect(DeviceState *dev)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
+
+    if (!i2c->connected) {
+        return;
+    }
+    i2c->connected = false;
+
+    if (i2c->vhost_dev.started) {
+        vu_i2c_stop(vdev);
+    }
+}
+
+static void vu_i2c_event(void *opaque, QEMUChrEvent event)
+{
+    DeviceState *dev = opaque;
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
+
+    switch (event) {
+    case CHR_EVENT_OPENED:
+        if (vu_i2c_connect(dev) < 0) {
+            qemu_chr_fe_disconnect(&i2c->conf.chardev);
+            return;
+        }
+        break;
+    case CHR_EVENT_CLOSED:
+        vu_i2c_disconnect(dev);
+        break;
+    case CHR_EVENT_BREAK:
+    case CHR_EVENT_MUX_IN:
+    case CHR_EVENT_MUX_OUT:
+        /* Ignore */
+        break;
+    }
+}
+
+static void vu_i2c_device_realize(DeviceState *dev, Error **errp)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VHostUserI2C *i2c = VHOST_USER_I2C(dev);
+    int ret;
+
+    if (!i2c->conf.chardev.chr) {
+        error_setg(errp, "missing chardev");
+        return;
+    }
+
+    if (!vhost_user_init(&i2c->vhost_user, &i2c->conf.chardev, errp)) {
+        return;
+    }
+
+    virtio_init(vdev, "vhost-user-i2c", VIRTIO_ID_I2C, 0);
+
+    i2c->req_vq = virtio_add_queue(vdev, 3, vu_i2c_handle_output);
+    i2c->vhost_dev.nvqs = 1;
+    i2c->vhost_dev.vqs = g_new0(struct vhost_virtqueue, i2c->vhost_dev.nvqs);
+    ret = vhost_dev_init(&i2c->vhost_dev, &i2c->vhost_user,
+                         VHOST_BACKEND_TYPE_USER, 0);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret, "vhost_dev_init() failed");
+        do_vhost_user_cleanup(vdev, i2c);
+    }
+
+    qemu_chr_fe_set_handlers(&i2c->conf.chardev, NULL, NULL, vu_i2c_event, NULL,
+                             dev, NULL, true);
+}
+
+static void vu_i2c_device_unrealize(DeviceState *dev)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VHostUserI2C *i2c = VHOST_USER_I2C(dev);
+
+    /* This will stop vhost backend if appropriate. */
+    vu_i2c_set_status(vdev, 0);
+
+    vhost_dev_cleanup(&i2c->vhost_dev);
+
+    do_vhost_user_cleanup(vdev, i2c);
+}
+
+static const VMStateDescription vu_i2c_vmstate = {
+    .name = "vhost-user-i2c",
+    .unmigratable = 1,
+};
+
+static Property vu_i2c_properties[] = {
+    DEFINE_PROP_CHR("chardev", VHostUserI2C, conf.chardev),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void vu_i2c_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
+
+    device_class_set_props(dc, vu_i2c_properties);
+    dc->vmsd = &vu_i2c_vmstate;
+    set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
+    vdc->realize = vu_i2c_device_realize;
+    vdc->unrealize = vu_i2c_device_unrealize;
+    vdc->get_features = vu_i2c_get_features;
+    vdc->set_status = vu_i2c_set_status;
+    vdc->guest_notifier_mask = vu_i2c_guest_notifier_mask;
+    vdc->guest_notifier_pending = vu_i2c_guest_notifier_pending;
+}
+
+static const TypeInfo vu_i2c_info = {
+    .name = TYPE_VHOST_USER_I2C,
+    .parent = TYPE_VIRTIO_DEVICE,
+    .instance_size = sizeof(VHostUserI2C),
+    .class_init = vu_i2c_class_init,
+};
+
+static void vu_i2c_register_types(void)
+{
+    type_register_static(&vu_i2c_info);
+}
+
+type_init(vu_i2c_register_types)
diff --git a/include/hw/virtio/vhost-user-i2c.h b/include/hw/virtio/vhost-user-i2c.h
new file mode 100644
index 000000000000..a5fffcb6096c
--- /dev/null
+++ b/include/hw/virtio/vhost-user-i2c.h
@@ -0,0 +1,37 @@ 
+/*
+ * Vhost-user i2c virtio device
+ *
+ * Copyright (c) 2021 Viresh Kumar <viresh.kumar@linaro.org>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef _QEMU_VHOST_USER_I2C_H
+#define _QEMU_VHOST_USER_I2C_H
+
+#include "hw/virtio/virtio.h"
+#include "hw/virtio/vhost.h"
+#include "hw/virtio/vhost-user.h"
+#include "chardev/char-fe.h"
+
+#define TYPE_VHOST_USER_I2C "vhost-user-i2c-device"
+OBJECT_DECLARE_SIMPLE_TYPE(VHostUserI2C, VHOST_USER_I2C)
+
+typedef struct {
+    CharBackend chardev;
+} VHostUserI2CConf;
+
+struct VHostUserI2C {
+    /*< private >*/
+    VirtIODevice parent;
+    VHostUserI2CConf conf;
+    struct vhost_virtqueue *vhost_vq;
+    struct vhost_dev vhost_dev;
+    VhostUserState vhost_user;
+    VirtQueue *req_vq;
+    bool connected;
+
+    /*< public >*/
+};
+
+#endif /* _QEMU_VHOST_USER_I2C_H */
diff --git a/include/standard-headers/linux/virtio_ids.h b/include/standard-headers/linux/virtio_ids.h
index bc1c0621f5ed..aba00c54b9cd 100644
--- a/include/standard-headers/linux/virtio_ids.h
+++ b/include/standard-headers/linux/virtio_ids.h
@@ -54,5 +54,6 @@ 
 #define VIRTIO_ID_FS			26 /* virtio filesystem */
 #define VIRTIO_ID_PMEM			27 /* virtio pmem */
 #define VIRTIO_ID_MAC80211_HWSIM	29 /* virtio mac80211-hwsim */
+#define VIRTIO_ID_I2C			34 /* virtio i2c */
 
 #endif /* _LINUX_VIRTIO_IDS_H */