On Mon, Jul 10, 2023 at 04:35:09PM +0100, Alex Bennée wrote: > In theory we shouldn't need to repeat so much boilerplate to support > vhost-user backends. This provides a generic vhost-user-base QOM > object and a derived vhost-user-device for which the user needs to > provide the few bits of information that aren't currently provided by > the vhost-user protocol. This should provide a baseline implementation > from which the other vhost-user stub can specialise. > > Signed-off-by: Alex Bennée <alex.ben...@linaro.org> > > --- > v2 > - split into vub and vud > --- > include/hw/virtio/vhost-user-device.h | 45 ++++ > hw/virtio/vhost-user-device.c | 324 ++++++++++++++++++++++++++ > hw/virtio/meson.build | 2 + > 3 files changed, 371 insertions(+) > create mode 100644 include/hw/virtio/vhost-user-device.h > create mode 100644 hw/virtio/vhost-user-device.c > > diff --git a/include/hw/virtio/vhost-user-device.h > b/include/hw/virtio/vhost-user-device.h > new file mode 100644 > index 0000000000..9105011e25 > --- /dev/null > +++ b/include/hw/virtio/vhost-user-device.h > @@ -0,0 +1,45 @@ > +/* > + * Vhost-user generic virtio device > + * > + * Copyright (c) 2023 Linaro Ltd > + * > + * SPDX-License-Identifier: GPL-2.0-or-later > + */ > + > +#ifndef QEMU_VHOST_USER_DEVICE_H > +#define QEMU_VHOST_USER_DEVICE_H > + > +#include "hw/virtio/vhost.h" > +#include "hw/virtio/vhost-user.h" > + > +#define TYPE_VHOST_USER_BASE "vhost-user-base" > + > +OBJECT_DECLARE_TYPE(VHostUserBase, VHostUserBaseClass, VHOST_USER_BASE) > + > +struct VHostUserBase { > + VirtIODevice parent; > + /* Properties */ > + CharBackend chardev; > + uint16_t virtio_id; > + uint32_t num_vqs; > + /* State tracking */ > + VhostUserState vhost_user; > + struct vhost_virtqueue *vhost_vq; > + struct vhost_dev vhost_dev; > + GPtrArray *vqs; > + bool connected; > +}; > + > + /* needed so we can use the base realize after specialisation > + tweaks */ > +struct VHostUserBaseClass { > + /*< private >*/ > + VirtioDeviceClass parent_class; > + /*< public >*/ > + DeviceRealize parent_realize; > +}; > + > +/* shared for the benefit of the derived pci class */ > +#define TYPE_VHOST_USER_DEVICE "vhost-user-device" > + > +#endif /* QEMU_VHOST_USER_DEVICE_H */ > diff --git a/hw/virtio/vhost-user-device.c b/hw/virtio/vhost-user-device.c > new file mode 100644 > index 0000000000..b0239fa033 > --- /dev/null > +++ b/hw/virtio/vhost-user-device.c > @@ -0,0 +1,324 @@ > +/* > + * Generic vhost-user stub. This can be used to connect to any > + * vhost-user backend. All configuration details must be handled by > + * the vhost-user daemon itself > + * > + * Copyright (c) 2023 Linaro Ltd > + * Author: Alex Bennée <alex.ben...@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-device.h" > +#include "qemu/error-report.h" > + > +static void vub_start(VirtIODevice *vdev) > +{ > + BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev))); > + VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus); > + VHostUserBase *vub = VHOST_USER_BASE(vdev); > + int ret, i; > + > + if (!k->set_guest_notifiers) { > + error_report("binding does not support guest notifiers"); > + return; > + } > + > + ret = vhost_dev_enable_notifiers(&vub->vhost_dev, vdev); > + if (ret < 0) { > + error_report("Error enabling host notifiers: %d", -ret); > + return; > + } > + > + ret = k->set_guest_notifiers(qbus->parent, vub->vhost_dev.nvqs, true); > + if (ret < 0) { > + error_report("Error binding guest notifier: %d", -ret); > + goto err_host_notifiers; > + } > + > + vub->vhost_dev.acked_features = vdev->guest_features; > + > + ret = vhost_dev_start(&vub->vhost_dev, vdev, true); > + if (ret < 0) { > + error_report("Error starting vhost-user-device: %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 < vub->vhost_dev.nvqs; i++) { > + vhost_virtqueue_mask(&vub->vhost_dev, vdev, i, false); > + } > + > + return; > + > +err_guest_notifiers: > + k->set_guest_notifiers(qbus->parent, vub->vhost_dev.nvqs, false); > +err_host_notifiers: > + vhost_dev_disable_notifiers(&vub->vhost_dev, vdev); > +} > + > +static void vub_stop(VirtIODevice *vdev) > +{ > + VHostUserBase *vub = VHOST_USER_BASE(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(&vub->vhost_dev, vdev, true); > + > + ret = k->set_guest_notifiers(qbus->parent, vub->vhost_dev.nvqs, false); > + if (ret < 0) { > + error_report("vhost guest notifier cleanup failed: %d", ret); > + return; > + } > + > + vhost_dev_disable_notifiers(&vub->vhost_dev, vdev); > +} > + > +static void vub_set_status(VirtIODevice *vdev, uint8_t status) > +{ > + VHostUserBase *vub = VHOST_USER_BASE(vdev); > + bool should_start = virtio_device_should_start(vdev, status); > + > + if (vhost_dev_is_started(&vub->vhost_dev) == should_start) { > + return; > + } > + > + if (should_start) { > + vub_start(vdev); > + } else { > + vub_stop(vdev); > + } > +} > + > +/* > + * For an implementation where everything is delegated to the backend > + * we don't do anything other than return the full feature set offered > + * by the daemon (module the reserved feature bit). > + */ > +static uint64_t vub_get_features(VirtIODevice *vdev, > + uint64_t requested_features, Error **errp) > +{ > + VHostUserBase *vub = VHOST_USER_BASE(vdev); > + /* This should be set when the vhost connection initialises */ > + g_assert(vub->vhost_dev.features); > + return vub->vhost_dev.features & ~(1ULL << > VHOST_USER_F_PROTOCOL_FEATURES); > +} > + > +static void vub_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 do_vhost_user_cleanup(VirtIODevice *vdev, VHostUserBase *vub) > +{ > + vhost_user_cleanup(&vub->vhost_user); > + > + for (int i = 0; i < vub->num_vqs; i++) { > + VirtQueue *vq = g_ptr_array_index(vub->vqs, i); > + virtio_delete_queue(vq); > + } > + > + virtio_cleanup(vdev); > +} > + > +static int vub_connect(DeviceState *dev) > +{ > + VirtIODevice *vdev = VIRTIO_DEVICE(dev); > + VHostUserBase *vub = VHOST_USER_BASE(vdev); > + > + if (vub->connected) { > + return 0; > + } > + vub->connected = true; > + > + /* restore vhost state */ > + if (virtio_device_started(vdev, vdev->status)) { > + vub_start(vdev); > + } > + > + return 0; > +} > + > +static void vub_disconnect(DeviceState *dev) > +{ > + VirtIODevice *vdev = VIRTIO_DEVICE(dev); > + VHostUserBase *vub = VHOST_USER_BASE(vdev); > + > + if (!vub->connected) { > + return; > + } > + vub->connected = false; > + > + if (vhost_dev_is_started(&vub->vhost_dev)) { > + vub_stop(vdev); > + } > +} > + > +static void vub_event(void *opaque, QEMUChrEvent event) > +{ > + DeviceState *dev = opaque; > + VirtIODevice *vdev = VIRTIO_DEVICE(dev); > + VHostUserBase *vub = VHOST_USER_BASE(vdev); > + > + switch (event) { > + case CHR_EVENT_OPENED: > + if (vub_connect(dev) < 0) { > + qemu_chr_fe_disconnect(&vub->chardev); > + return; > + } > + break; > + case CHR_EVENT_CLOSED: > + vub_disconnect(dev); > + break; > + case CHR_EVENT_BREAK: > + case CHR_EVENT_MUX_IN: > + case CHR_EVENT_MUX_OUT: > + /* Ignore */ > + break; > + } > +} > + > +static void vub_device_realize(DeviceState *dev, Error **errp) > +{ > + VirtIODevice *vdev = VIRTIO_DEVICE(dev); > + VHostUserBase *vub = VHOST_USER_BASE(dev); > + int ret; > + > + if (!vub->chardev.chr) { > + error_setg(errp, "vhost-user-device: missing chardev"); > + return; > + } > + > + if (!vub->virtio_id) { > + error_setg(errp, "vhost-user-device: need to define device id"); > + return; > + } > + > + if (!vub->num_vqs) { > + vub->num_vqs = 1; /* reasonable default? */ > + } > + > + if (!vhost_user_init(&vub->vhost_user, &vub->chardev, errp)) { > + return; > + } > + > + virtio_init(vdev, vub->virtio_id, 0); > + > + /* > + * Disable guest notifiers, by default all notifications will be via the > + * asynchronous vhost-user socket. > + */ > + vdev->use_guest_notifier_mask = false; > + > + /* Allocate queues */ > + vub->vqs = g_ptr_array_sized_new(vub->num_vqs); > + for (int i = 0; i < vub->num_vqs; i++) { > + g_ptr_array_add(vub->vqs, > + virtio_add_queue(vdev, 4, vub_handle_output)); > + } > +
Hello Alex, apologies if someone already asked this. If I understand correctly, the second parameter of virtio_add_queue() is the len of the queue. Why have you chosen "4" as its value? Shall qemu query the len of the queue from the vhost-user device instead? Matias