Now the new base class supports config handling we can take advantage
and make vhost-user-gpio a much simpler boilerplate wrapper. Also as
this doesn't require any target specific hacks we only need to build
the stubs once.

Message-Id: <20230418162140.373219-12-alex.bennee@linaro.org>
Acked-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20231009095937.195728-4-alex.bennee@linaro.org>
---
 include/hw/virtio/vhost-user-gpio.h |  23 +-
 hw/virtio/vhost-user-gpio.c         | 406 ++--------------------------
 hw/virtio/meson.build               |   5 +-
 3 files changed, 22 insertions(+), 412 deletions(-)

diff --git a/include/hw/virtio/vhost-user-gpio.h b/include/hw/virtio/vhost-user-gpio.h
index a9d3f9b049..5201d5f072 100644
--- a/include/hw/virtio/vhost-user-gpio.h
+++ b/include/hw/virtio/vhost-user-gpio.h
@@ -12,33 +12,14 @@
 #include "hw/virtio/virtio.h"
 #include "hw/virtio/vhost.h"
 #include "hw/virtio/vhost-user.h"
-#include "standard-headers/linux/virtio_gpio.h"
-#include "chardev/char-fe.h"
+#include "hw/virtio/vhost-user-base.h"
 
 #define TYPE_VHOST_USER_GPIO "vhost-user-gpio-device"
 OBJECT_DECLARE_SIMPLE_TYPE(VHostUserGPIO, VHOST_USER_GPIO);
 
 struct VHostUserGPIO {
     /*< private >*/
-    VirtIODevice parent_obj;
-    CharBackend chardev;
-    struct virtio_gpio_config config;
-    struct vhost_virtqueue *vhost_vqs;
-    struct vhost_dev vhost_dev;
-    VhostUserState vhost_user;
-    VirtQueue *command_vq;
-    VirtQueue *interrupt_vq;
-    /**
-     * There are at least two steps of initialization of the
-     * vhost-user device. The first is a "connect" step and
-     * second is a "start" step. Make a separation between
-     * those initialization phases by using two fields.
-     *
-     * @connected: see vu_gpio_connect()/vu_gpio_disconnect()
-     * @started_vu: see vu_gpio_start()/vu_gpio_stop()
-     */
-    bool connected;
-    bool started_vu;
+    VHostUserBase parent;
     /*< public >*/
 };
 
diff --git a/hw/virtio/vhost-user-gpio.c b/hw/virtio/vhost-user-gpio.c
index aff2d7eff6..9f37c25415 100644
--- a/hw/virtio/vhost-user-gpio.c
+++ b/hw/virtio/vhost-user-gpio.c
@@ -11,387 +11,25 @@
 #include "hw/qdev-properties.h"
 #include "hw/virtio/virtio-bus.h"
 #include "hw/virtio/vhost-user-gpio.h"
-#include "qemu/error-report.h"
 #include "standard-headers/linux/virtio_ids.h"
-#include "trace.h"
+#include "standard-headers/linux/virtio_gpio.h"
 
-#define VHOST_NVQS 2
-
-/* Features required from VirtIO */
-static const int feature_bits[] = {
-    VIRTIO_F_VERSION_1,
-    VIRTIO_F_NOTIFY_ON_EMPTY,
-    VIRTIO_RING_F_INDIRECT_DESC,
-    VIRTIO_RING_F_EVENT_IDX,
-    VIRTIO_GPIO_F_IRQ,
-    VIRTIO_F_RING_RESET,
-    VHOST_INVALID_FEATURE_BIT
-};
-
-static void vu_gpio_get_config(VirtIODevice *vdev, uint8_t *config)
-{
-    VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
-
-    memcpy(config, &gpio->config, sizeof(gpio->config));
-}
-
-static int vu_gpio_config_notifier(struct vhost_dev *dev)
-{
-    VHostUserGPIO *gpio = VHOST_USER_GPIO(dev->vdev);
-
-    memcpy(dev->vdev->config, &gpio->config, sizeof(gpio->config));
-    virtio_notify_config(dev->vdev);
-
-    return 0;
-}
-
-const VhostDevConfigOps gpio_ops = {
-    .vhost_dev_config_notifier = vu_gpio_config_notifier,
+static Property vgpio_properties[] = {
+    DEFINE_PROP_CHR("chardev", VHostUserBase, chardev),
+    DEFINE_PROP_END_OF_LIST(),
 };
 
-static int vu_gpio_start(VirtIODevice *vdev)
-{
-    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
-    VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
-    struct vhost_dev *vhost_dev = &gpio->vhost_dev;
-    int ret, i;
-
-    if (!k->set_guest_notifiers) {
-        error_report("binding does not support guest notifiers");
-        return -ENOSYS;
-    }
-
-    ret = vhost_dev_enable_notifiers(vhost_dev, vdev);
-    if (ret < 0) {
-        error_report("Error enabling host notifiers: %d", ret);
-        return ret;
-    }
-
-    ret = k->set_guest_notifiers(qbus->parent, vhost_dev->nvqs, true);
-    if (ret < 0) {
-        error_report("Error binding guest notifier: %d", ret);
-        goto err_host_notifiers;
-    }
-
-    /*
-     * Before we start up we need to ensure we have the final feature
-     * set needed for the vhost configuration. The backend may also
-     * apply backend_features when the feature set is sent.
-     */
-    vhost_ack_features(&gpio->vhost_dev, feature_bits, vdev->guest_features);
-
-    ret = vhost_dev_start(&gpio->vhost_dev, vdev, false);
-    if (ret < 0) {
-        error_report("Error starting vhost-user-gpio: %d", ret);
-        goto err_guest_notifiers;
-    }
-    gpio->started_vu = true;
-
-    /*
-     * 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 < gpio->vhost_dev.nvqs; i++) {
-        vhost_virtqueue_mask(&gpio->vhost_dev, vdev, i, false);
-    }
-
-    /*
-     * As we must have VHOST_USER_F_PROTOCOL_FEATURES (because
-     * VHOST_USER_GET_CONFIG requires it) we need to explicitly enable
-     * the vrings.
-     */
-    g_assert(vhost_dev->vhost_ops &&
-             vhost_dev->vhost_ops->vhost_set_vring_enable);
-    ret = vhost_dev->vhost_ops->vhost_set_vring_enable(vhost_dev, true);
-    if (ret == 0) {
-        return 0;
-    }
-
-    error_report("Failed to start vrings for vhost-user-gpio: %d", ret);
-
-err_guest_notifiers:
-    k->set_guest_notifiers(qbus->parent, gpio->vhost_dev.nvqs, false);
-err_host_notifiers:
-    vhost_dev_disable_notifiers(&gpio->vhost_dev, vdev);
-
-    return ret;
-}
-
-static void vu_gpio_stop(VirtIODevice *vdev)
-{
-    VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
-    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
-    struct vhost_dev *vhost_dev = &gpio->vhost_dev;
-    int ret;
-
-    if (!gpio->started_vu) {
-        return;
-    }
-    gpio->started_vu = false;
-
-    if (!k->set_guest_notifiers) {
-        return;
-    }
-
-    vhost_dev_stop(vhost_dev, vdev, false);
-
-    ret = k->set_guest_notifiers(qbus->parent, vhost_dev->nvqs, false);
-    if (ret < 0) {
-        error_report("vhost guest notifier cleanup failed: %d", ret);
-        return;
-    }
-
-    vhost_dev_disable_notifiers(vhost_dev, vdev);
-}
-
-static void vu_gpio_set_status(VirtIODevice *vdev, uint8_t status)
-{
-    VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
-    bool should_start = virtio_device_should_start(vdev, status);
-
-    trace_virtio_gpio_set_status(status);
-
-    if (!gpio->connected) {
-        return;
-    }
-
-    if (vhost_dev_is_started(&gpio->vhost_dev) == should_start) {
-        return;
-    }
-
-    if (should_start) {
-        if (vu_gpio_start(vdev)) {
-            qemu_chr_fe_disconnect(&gpio->chardev);
-        }
-    } else {
-        vu_gpio_stop(vdev);
-    }
-}
-
-static uint64_t vu_gpio_get_features(VirtIODevice *vdev, uint64_t features,
-                                     Error **errp)
-{
-    VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
-
-    return vhost_get_features(&gpio->vhost_dev, feature_bits, features);
-}
-
-static void vu_gpio_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_gpio_guest_notifier_mask(VirtIODevice *vdev, int idx, bool mask)
-{
-    VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
-
-    /*
-     * Add the check for configure interrupt, Use VIRTIO_CONFIG_IRQ_IDX -1
-     * as the macro of configure interrupt's IDX, If this driver does not
-     * support, the function will return
-     */
-
-    if (idx == VIRTIO_CONFIG_IRQ_IDX) {
-        return;
-    }
-
-    vhost_virtqueue_mask(&gpio->vhost_dev, vdev, idx, mask);
-}
-
-static struct vhost_dev *vu_gpio_get_vhost(VirtIODevice *vdev)
-{
-    VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
-    return &gpio->vhost_dev;
-}
-
-static void do_vhost_user_cleanup(VirtIODevice *vdev, VHostUserGPIO *gpio)
-{
-    virtio_delete_queue(gpio->command_vq);
-    virtio_delete_queue(gpio->interrupt_vq);
-    g_free(gpio->vhost_vqs);
-    virtio_cleanup(vdev);
-    vhost_user_cleanup(&gpio->vhost_user);
-}
-
-static int vu_gpio_connect(DeviceState *dev, Error **errp)
-{
-    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
-    VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
-    struct vhost_dev *vhost_dev = &gpio->vhost_dev;
-    int ret;
-
-    if (gpio->connected) {
-        return 0;
-    }
-    gpio->connected = true;
-
-    vhost_dev_set_config_notifier(vhost_dev, &gpio_ops);
-    gpio->vhost_user.supports_config = true;
-
-    gpio->vhost_dev.nvqs = VHOST_NVQS;
-    gpio->vhost_dev.vqs = gpio->vhost_vqs;
-
-    ret = vhost_dev_init(vhost_dev, &gpio->vhost_user,
-                         VHOST_BACKEND_TYPE_USER, 0, errp);
-    if (ret < 0) {
-        return ret;
-    }
-
-    /* restore vhost state */
-    if (virtio_device_started(vdev, vdev->status)) {
-        vu_gpio_start(vdev);
-    }
-
-    return 0;
-}
-
-static void vu_gpio_event(void *opaque, QEMUChrEvent event);
-
-static void vu_gpio_disconnect(DeviceState *dev)
-{
-    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
-    VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
-
-    if (!gpio->connected) {
-        return;
-    }
-    gpio->connected = false;
-
-    vu_gpio_stop(vdev);
-    vhost_dev_cleanup(&gpio->vhost_dev);
-
-    /* Re-instate the event handler for new connections */
-    qemu_chr_fe_set_handlers(&gpio->chardev,
-                             NULL, NULL, vu_gpio_event,
-                             NULL, dev, NULL, true);
-}
-
-static void vu_gpio_event(void *opaque, QEMUChrEvent event)
-{
-    DeviceState *dev = opaque;
-    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
-    VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
-    Error *local_err = NULL;
-
-    switch (event) {
-    case CHR_EVENT_OPENED:
-        if (vu_gpio_connect(dev, &local_err) < 0) {
-            qemu_chr_fe_disconnect(&gpio->chardev);
-            return;
-        }
-        break;
-    case CHR_EVENT_CLOSED:
-        /* defer close until later to avoid circular close */
-        vhost_user_async_close(dev, &gpio->chardev, &gpio->vhost_dev,
-                               vu_gpio_disconnect, vu_gpio_event);
-        break;
-    case CHR_EVENT_BREAK:
-    case CHR_EVENT_MUX_IN:
-    case CHR_EVENT_MUX_OUT:
-        /* Ignore */
-        break;
-    }
-}
-
-static int vu_gpio_realize_connect(VHostUserGPIO *gpio, Error **errp)
+static void vgpio_realize(DeviceState *dev, Error **errp)
 {
-    VirtIODevice *vdev = &gpio->parent_obj;
-    DeviceState *dev = &vdev->parent_obj;
-    struct vhost_dev *vhost_dev = &gpio->vhost_dev;
-    int ret;
-
-    ret = qemu_chr_fe_wait_connected(&gpio->chardev, errp);
-    if (ret < 0) {
-        return ret;
-    }
-
-    /*
-     * vu_gpio_connect() may have already connected (via the event
-     * callback) in which case it will just report success.
-     */
-    ret = vu_gpio_connect(dev, errp);
-    if (ret < 0) {
-        qemu_chr_fe_disconnect(&gpio->chardev);
-        return ret;
-    }
-    g_assert(gpio->connected);
-
-    ret = vhost_dev_get_config(vhost_dev, (uint8_t *)&gpio->config,
-                               sizeof(gpio->config), errp);
-
-    if (ret < 0) {
-        error_report("vhost-user-gpio: get config failed");
-
-        qemu_chr_fe_disconnect(&gpio->chardev);
-        vhost_dev_cleanup(vhost_dev);
-        return ret;
-    }
-
-    return 0;
-}
-
-static void vu_gpio_device_realize(DeviceState *dev, Error **errp)
-{
-    ERRP_GUARD();
-
-    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
-    VHostUserGPIO *gpio = VHOST_USER_GPIO(dev);
-    int retries, ret;
-
-    if (!gpio->chardev.chr) {
-        error_setg(errp, "vhost-user-gpio: chardev is mandatory");
-        return;
-    }
+    VHostUserBase *vub = VHOST_USER_BASE(dev);
+    VHostUserBaseClass *vubc = VHOST_USER_BASE_GET_CLASS(dev);
 
-    if (!vhost_user_init(&gpio->vhost_user, &gpio->chardev, errp)) {
-        return;
-    }
+    /* Fixed for GPIO */
+    vub->virtio_id = VIRTIO_ID_GPIO;
+    vub->num_vqs = 2;
+    vub->config_size = sizeof(struct virtio_gpio_config);
 
-    virtio_init(vdev, VIRTIO_ID_GPIO, sizeof(gpio->config));
-
-    gpio->command_vq = virtio_add_queue(vdev, 256, vu_gpio_handle_output);
-    gpio->interrupt_vq = virtio_add_queue(vdev, 256, vu_gpio_handle_output);
-    gpio->vhost_vqs = g_new0(struct vhost_virtqueue, VHOST_NVQS);
-
-    gpio->connected = false;
-
-    qemu_chr_fe_set_handlers(&gpio->chardev, NULL, NULL, vu_gpio_event, NULL,
-                             dev, NULL, true);
-
-    retries = VU_REALIZE_CONN_RETRIES;
-    g_assert(!*errp);
-    do {
-        if (*errp) {
-            error_prepend(errp, "Reconnecting after error: ");
-            error_report_err(*errp);
-            *errp = NULL;
-        }
-        ret = vu_gpio_realize_connect(gpio, errp);
-    } while (ret < 0 && retries--);
-
-    if (ret < 0) {
-        do_vhost_user_cleanup(vdev, gpio);
-    }
-
-    return;
-}
-
-static void vu_gpio_device_unrealize(DeviceState *dev)
-{
-    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
-    VHostUserGPIO *gpio = VHOST_USER_GPIO(dev);
-
-    vu_gpio_set_status(vdev, 0);
-    qemu_chr_fe_set_handlers(&gpio->chardev, NULL, NULL, NULL, NULL, NULL, NULL,
-                             false);
-    vhost_dev_cleanup(&gpio->vhost_dev);
-    do_vhost_user_cleanup(vdev, gpio);
+    vubc->parent_realize(dev, errp);
 }
 
 static const VMStateDescription vu_gpio_vmstate = {
@@ -399,31 +37,21 @@ static const VMStateDescription vu_gpio_vmstate = {
     .unmigratable = 1,
 };
 
-static Property vu_gpio_properties[] = {
-    DEFINE_PROP_CHR("chardev", VHostUserGPIO, chardev),
-    DEFINE_PROP_END_OF_LIST(),
-};
-
 static void vu_gpio_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
-    VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
+    VHostUserBaseClass *vubc = VHOST_USER_BASE_CLASS(klass);
 
-    device_class_set_props(dc, vu_gpio_properties);
     dc->vmsd = &vu_gpio_vmstate;
+    device_class_set_props(dc, vgpio_properties);
+    device_class_set_parent_realize(dc, vgpio_realize,
+                                    &vubc->parent_realize);
     set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
-    vdc->realize = vu_gpio_device_realize;
-    vdc->unrealize = vu_gpio_device_unrealize;
-    vdc->get_features = vu_gpio_get_features;
-    vdc->get_config = vu_gpio_get_config;
-    vdc->set_status = vu_gpio_set_status;
-    vdc->guest_notifier_mask = vu_gpio_guest_notifier_mask;
-    vdc->get_vhost = vu_gpio_get_vhost;
 }
 
 static const TypeInfo vu_gpio_info = {
     .name = TYPE_VHOST_USER_GPIO,
-    .parent = TYPE_VIRTIO_DEVICE,
+    .parent = TYPE_VHOST_USER_BASE,
     .instance_size = sizeof(VHostUserGPIO),
     .class_init = vu_gpio_class_init,
 };
diff --git a/hw/virtio/meson.build b/hw/virtio/meson.build
index b5c1a461e3..87042e5901 100644
--- a/hw/virtio/meson.build
+++ b/hw/virtio/meson.build
@@ -21,10 +21,13 @@ if have_vhost
 
     # MMIO Stubs
     system_virtio_ss.add(files('vhost-user-device.c'))
+    system_virtio_ss.add(when: 'CONFIG_VHOST_USER_GPIO', if_true: files('vhost-user-gpio.c'))
     system_virtio_ss.add(when: 'CONFIG_VHOST_USER_RNG', if_true: files('vhost-user-rng.c'))
 
     # PCI Stubs
     system_virtio_ss.add(when: 'CONFIG_VIRTIO_PCI', if_true: files('vhost-user-device-pci.c'))
+    system_virtio_ss.add(when: ['CONFIG_VIRTIO_PCI', 'CONFIG_VHOST_USER_GPIO'],
+                         if_true: files('vhost-user-gpio-pci.c'))
     system_virtio_ss.add(when: ['CONFIG_VIRTIO_PCI', 'CONFIG_VHOST_USER_RNG'],
                          if_true: files('vhost-user-rng-pci.c'))
   endif
@@ -44,8 +47,6 @@ specific_virtio_ss.add(when: 'CONFIG_VHOST_USER_VSOCK', if_true: files('vhost-us
 specific_virtio_ss.add(when: 'CONFIG_VIRTIO_RNG', if_true: files('virtio-rng.c'))
 specific_virtio_ss.add(when: 'CONFIG_VIRTIO_MEM', if_true: files('virtio-mem.c'))
 specific_virtio_ss.add(when: 'CONFIG_VHOST_USER_I2C', if_true: files('vhost-user-i2c.c'))
-specific_virtio_ss.add(when: 'CONFIG_VHOST_USER_GPIO', if_true: files('vhost-user-gpio.c'))
-specific_virtio_ss.add(when: ['CONFIG_VIRTIO_PCI', 'CONFIG_VHOST_USER_GPIO'], if_true: files('vhost-user-gpio-pci.c'))
 specific_virtio_ss.add(when: 'CONFIG_VHOST_USER_SCMI', if_true: files('vhost-user-scmi.c'))
 specific_virtio_ss.add(when: ['CONFIG_VIRTIO_PCI', 'CONFIG_VHOST_USER_SCMI'], if_true: files('vhost-user-scmi-pci.c'))
 
-- 
2.39.2

On Mon, Nov 06, 2023 at 07:15:12PM +0000, Alex Bennée wrote:
> -    case CHR_EVENT_CLOSED:
> -        /* defer close until later to avoid circular close */
> -        vhost_user_async_close(dev, &gpio->chardev, &gpio->vhost_dev,
> -                               vu_gpio_disconnect, vu_gpio_event);

I don't remember what is the circular close but I'd be much
calmer if this refactoring also didn't change behaviour.
Or if it does, please document why it's safe in the commit log.

-- 
MST