[PATCH v3 0/3] Add SCMI vhost-user VIRTIO device

[PATCH v3 0/3] Add SCMI vhost-user VIRTIO device

[Milan Zamazal]

This patch series adds a vhost-user VIRTIO device for SCMI.
It's similar to other similar vhost-user VIRTIO devices.

I'm aware of the work in progress by Alex Bennée to simplify similar devices
and avoid excessive code duplication.  I think the SCMI device support
doesn't bring anything special and it can be rebased on the given work
if/once it is merged.

The device has been tested with a prototype rust-vmm based
vhost-user-scmi daemon emulating a sensor device and a Linux guest OS
(the production version of the vhost-user daemon is developed at
https://github.com/mz-pdm/vhost-device/tree/scmi).

v3:
 - Rebased on master after one of the patches had been merged.
v2:
 - A missing trailing space additionally added in the comment typo fix.
 - A note about testing added above.

Milan Zamazal (3):
  hw/virtio: Add boilerplate for vhost-user-scmi device
  hw/virtio: Add vhost-user-scmi-pci boilerplate
  tests/qtest: enable tests for virtio-scmi

 MAINTAINERS                         |   7 +
 hw/virtio/Kconfig                   |   5 +
 hw/virtio/meson.build               |   2 +
 hw/virtio/vhost-user-scmi-pci.c     |  68 +++++++
 hw/virtio/vhost-user-scmi.c         | 306 ++++++++++++++++++++++++++++
 include/hw/virtio/vhost-user-scmi.h |  30 +++
 tests/qtest/libqos/meson.build      |   1 +
 tests/qtest/libqos/virtio-scmi.c    | 174 ++++++++++++++++
 tests/qtest/libqos/virtio-scmi.h    |  34 ++++
 tests/qtest/vhost-user-test.c       |  44 ++++
 10 files changed, 671 insertions(+)
 create mode 100644 hw/virtio/vhost-user-scmi-pci.c
 create mode 100644 hw/virtio/vhost-user-scmi.c
 create mode 100644 include/hw/virtio/vhost-user-scmi.h
 create mode 100644 tests/qtest/libqos/virtio-scmi.c
 create mode 100644 tests/qtest/libqos/virtio-scmi.h

-- 
2.40.1

[PATCH v3 1/3] hw/virtio: Add boilerplate for vhost-user-scmi device

[Milan Zamazal]

This creates the QEMU side of the vhost-user-scmi device which connects to
the remote daemon.  It is based on code of similar vhost-user devices.

Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
---
 MAINTAINERS                         |   6 +
 hw/virtio/Kconfig                   |   5 +
 hw/virtio/meson.build               |   1 +
 hw/virtio/vhost-user-scmi.c         | 306 ++++++++++++++++++++++++++++
 include/hw/virtio/vhost-user-scmi.h |  30 +++
 5 files changed, 348 insertions(+)
 create mode 100644 hw/virtio/vhost-user-scmi.c
 create mode 100644 include/hw/virtio/vhost-user-scmi.h

diff --git a/MAINTAINERS b/MAINTAINERS
index e07746ac7d..7ddb8268fe 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2210,6 +2210,12 @@ F: hw/virtio/vhost-user-gpio*
 F: include/hw/virtio/vhost-user-gpio.h
 F: tests/qtest/libqos/virtio-gpio.*
 
+vhost-user-scmi
+R: mzamazal@redhat.com
+S: Supported
+F: hw/virtio/vhost-user-scmi*
+F: include/hw/virtio/vhost-user-scmi.h
+
 virtio-crypto
 M: Gonglei <arei.gonglei@huawei.com>
 S: Supported
diff --git a/hw/virtio/Kconfig b/hw/virtio/Kconfig
index de7a35429a..a9ee09062f 100644
--- a/hw/virtio/Kconfig
+++ b/hw/virtio/Kconfig
@@ -96,3 +96,8 @@ config VHOST_VDPA_DEV
     bool
     default y
     depends on VIRTIO && VHOST_VDPA && LINUX
+
+config VHOST_USER_SCMI
+    bool
+    default y
+    depends on VIRTIO && VHOST_USER
diff --git a/hw/virtio/meson.build b/hw/virtio/meson.build
index f32b22f61b..4a4d7e1c27 100644
--- a/hw/virtio/meson.build
+++ b/hw/virtio/meson.build
@@ -35,6 +35,7 @@ specific_virtio_ss.add(when: 'CONFIG_VHOST_USER_I2C', if_true: files('vhost-user
 specific_virtio_ss.add(when: 'CONFIG_VHOST_USER_RNG', if_true: files('vhost-user-rng.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'))
 
 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-scmi.c b/hw/virtio/vhost-user-scmi.c
new file mode 100644
index 0000000000..d386fb2df9
--- /dev/null
+++ b/hw/virtio/vhost-user-scmi.c
@@ -0,0 +1,306 @@
+/*
+ * Vhost-user SCMI virtio device
+ *
+ * SPDX-FileCopyrightText: Red Hat, Inc.
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * Implementation based on other vhost-user devices in QEMU.
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qemu/error-report.h"
+#include "hw/virtio/virtio-bus.h"
+#include "hw/virtio/vhost-user-scmi.h"
+#include "standard-headers/linux/virtio_ids.h"
+#include "standard-headers/linux/virtio_scmi.h"
+#include "trace.h"
+
+/*
+ * In this version, we don't support VIRTIO_SCMI_F_SHARED_MEMORY.
+ * Note that VIRTIO_SCMI_F_SHARED_MEMORY is currently not supported in
+ * Linux VirtIO SCMI guest driver.
+ */
+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_F_RING_RESET,
+    VIRTIO_SCMI_F_P2A_CHANNELS,
+    VHOST_INVALID_FEATURE_BIT
+};
+
+static int vu_scmi_start(VirtIODevice *vdev)
+{
+    VHostUserSCMI *scmi = VHOST_USER_SCMI(vdev);
+    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
+    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+    struct vhost_dev *vhost_dev = &scmi->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;
+    }
+
+    vhost_ack_features(&scmi->vhost_dev, feature_bits, vdev->guest_features);
+
+    ret = vhost_dev_start(&scmi->vhost_dev, vdev, true);
+    if (ret < 0) {
+        error_report("Error starting vhost-user-scmi: %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 < scmi->vhost_dev.nvqs; i++) {
+        vhost_virtqueue_mask(&scmi->vhost_dev, vdev, i, false);
+    }
+    return 0;
+
+err_guest_notifiers:
+    k->set_guest_notifiers(qbus->parent, vhost_dev->nvqs, false);
+err_host_notifiers:
+    vhost_dev_disable_notifiers(vhost_dev, vdev);
+
+    return ret;
+}
+
+static void vu_scmi_stop(VirtIODevice *vdev)
+{
+    VHostUserSCMI *scmi = VHOST_USER_SCMI(vdev);
+    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
+    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+    struct vhost_dev *vhost_dev = &scmi->vhost_dev;
+    int ret;
+
+    if (!k->set_guest_notifiers) {
+        return;
+    }
+
+    vhost_dev_stop(vhost_dev, vdev, true);
+
+    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_scmi_set_status(VirtIODevice *vdev, uint8_t status)
+{
+    VHostUserSCMI *scmi = VHOST_USER_SCMI(vdev);
+    bool should_start = virtio_device_should_start(vdev, status);
+
+    if (!scmi->connected) {
+        return;
+    }
+    if (vhost_dev_is_started(&scmi->vhost_dev) == should_start) {
+        return;
+    }
+
+    if (should_start) {
+        vu_scmi_start(vdev);
+    } else {
+        vu_scmi_stop(vdev);
+    }
+}
+
+static uint64_t vu_scmi_get_features(VirtIODevice *vdev, uint64_t features,
+                                     Error **errp)
+{
+    VHostUserSCMI *scmi = VHOST_USER_SCMI(vdev);
+
+    return vhost_get_features(&scmi->vhost_dev, feature_bits, features);
+}
+
+static void vu_scmi_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_scmi_guest_notifier_mask(VirtIODevice *vdev, int idx, bool mask)
+{
+    VHostUserSCMI *scmi = VHOST_USER_SCMI(vdev);
+
+    if (idx == VIRTIO_CONFIG_IRQ_IDX) {
+        return;
+    }
+
+    vhost_virtqueue_mask(&scmi->vhost_dev, vdev, idx, mask);
+}
+
+static bool vu_scmi_guest_notifier_pending(VirtIODevice *vdev, int idx)
+{
+    VHostUserSCMI *scmi = VHOST_USER_SCMI(vdev);
+
+    return vhost_virtqueue_pending(&scmi->vhost_dev, idx);
+}
+
+static void vu_scmi_connect(DeviceState *dev)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VHostUserSCMI *scmi = VHOST_USER_SCMI(vdev);
+
+    if (scmi->connected) {
+        return;
+    }
+    scmi->connected = true;
+
+    /* restore vhost state */
+    if (virtio_device_started(vdev, vdev->status)) {
+        vu_scmi_start(vdev);
+    }
+}
+
+static void vu_scmi_disconnect(DeviceState *dev)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VHostUserSCMI *scmi = VHOST_USER_SCMI(vdev);
+
+    if (!scmi->connected) {
+        return;
+    }
+    scmi->connected = false;
+
+    if (vhost_dev_is_started(&scmi->vhost_dev)) {
+        vu_scmi_stop(vdev);
+    }
+}
+
+static void vu_scmi_event(void *opaque, QEMUChrEvent event)
+{
+    DeviceState *dev = opaque;
+
+    switch (event) {
+    case CHR_EVENT_OPENED:
+        vu_scmi_connect(dev);
+        break;
+    case CHR_EVENT_CLOSED:
+        vu_scmi_disconnect(dev);
+        break;
+    case CHR_EVENT_BREAK:
+    case CHR_EVENT_MUX_IN:
+    case CHR_EVENT_MUX_OUT:
+        /* Ignore */
+        break;
+    }
+}
+
+static void do_vhost_user_cleanup(VirtIODevice *vdev, VHostUserSCMI *scmi)
+{
+    virtio_delete_queue(scmi->cmd_vq);
+    virtio_delete_queue(scmi->event_vq);
+    g_free(scmi->vhost_dev.vqs);
+    virtio_cleanup(vdev);
+    vhost_user_cleanup(&scmi->vhost_user);
+}
+
+static void vu_scmi_device_realize(DeviceState *dev, Error **errp)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VHostUserSCMI *scmi = VHOST_USER_SCMI(dev);
+    int ret;
+
+    if (!scmi->chardev.chr) {
+        error_setg(errp, "vhost-user-scmi: chardev is mandatory");
+        return;
+    }
+
+    vdev->host_features |= (1ULL << VIRTIO_SCMI_F_P2A_CHANNELS);
+
+    if (!vhost_user_init(&scmi->vhost_user, &scmi->chardev, errp)) {
+        return;
+    }
+
+    virtio_init(vdev, VIRTIO_ID_SCMI, 0);
+
+    scmi->cmd_vq = virtio_add_queue(vdev, 256, vu_scmi_handle_output);
+    scmi->event_vq = virtio_add_queue(vdev, 256, vu_scmi_handle_output);
+    scmi->vhost_dev.nvqs = 2;
+    scmi->vhost_dev.vqs = g_new0(struct vhost_virtqueue, scmi->vhost_dev.nvqs);
+
+    ret = vhost_dev_init(&scmi->vhost_dev, &scmi->vhost_user,
+                         VHOST_BACKEND_TYPE_USER, 0, errp);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret,
+                         "vhost-user-scmi: vhost_dev_init() failed");
+        do_vhost_user_cleanup(vdev, scmi);
+        return;
+    }
+
+    qemu_chr_fe_set_handlers(&scmi->chardev, NULL, NULL, vu_scmi_event, NULL,
+                             dev, NULL, true);
+
+    return;
+}
+
+static void vu_scmi_device_unrealize(DeviceState *dev)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VHostUserSCMI *scmi = VHOST_USER_SCMI(dev);
+
+    vu_scmi_set_status(vdev, 0);
+    vhost_dev_cleanup(&scmi->vhost_dev);
+    do_vhost_user_cleanup(vdev, scmi);
+}
+
+static const VMStateDescription vu_scmi_vmstate = {
+    .name = "vhost-user-scmi",
+    .unmigratable = 1,
+};
+
+static Property vu_scmi_properties[] = {
+    DEFINE_PROP_CHR("chardev", VHostUserSCMI, chardev),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void vu_scmi_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
+
+    device_class_set_props(dc, vu_scmi_properties);
+    dc->vmsd = &vu_scmi_vmstate;
+    set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
+    vdc->realize = vu_scmi_device_realize;
+    vdc->unrealize = vu_scmi_device_unrealize;
+    vdc->get_features = vu_scmi_get_features;
+    vdc->set_status = vu_scmi_set_status;
+    vdc->guest_notifier_mask = vu_scmi_guest_notifier_mask;
+    vdc->guest_notifier_pending = vu_scmi_guest_notifier_pending;
+}
+
+static const TypeInfo vu_scmi_info = {
+    .name = TYPE_VHOST_USER_SCMI,
+    .parent = TYPE_VIRTIO_DEVICE,
+    .instance_size = sizeof(VHostUserSCMI),
+    .class_init = vu_scmi_class_init,
+};
+
+static void vu_scmi_register_types(void)
+{
+    type_register_static(&vu_scmi_info);
+}
+
+type_init(vu_scmi_register_types)
diff --git a/include/hw/virtio/vhost-user-scmi.h b/include/hw/virtio/vhost-user-scmi.h
new file mode 100644
index 0000000000..6175a74ebd
--- /dev/null
+++ b/include/hw/virtio/vhost-user-scmi.h
@@ -0,0 +1,30 @@
+/*
+ * Vhost-user SCMI virtio device
+ *
+ * Copyright (c) 2023 Red Hat, Inc.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef _QEMU_VHOST_USER_SCMI_H
+#define _QEMU_VHOST_USER_SCMI_H
+
+#include "hw/virtio/virtio.h"
+#include "hw/virtio/vhost.h"
+#include "hw/virtio/vhost-user.h"
+
+#define TYPE_VHOST_USER_SCMI "vhost-user-scmi"
+OBJECT_DECLARE_SIMPLE_TYPE(VHostUserSCMI, VHOST_USER_SCMI);
+
+struct VHostUserSCMI {
+    VirtIODevice parent;
+    CharBackend chardev;
+    struct vhost_virtqueue *vhost_vqs;
+    struct vhost_dev vhost_dev;
+    VhostUserState vhost_user;
+    VirtQueue *cmd_vq;
+    VirtQueue *event_vq;
+    bool connected;
+};
+
+#endif /* _QEMU_VHOST_USER_SCMI_H */
-- 
2.40.1

[PATCH v3 2/3] hw/virtio: Add vhost-user-scmi-pci boilerplate

[Milan Zamazal]

This allows is to instantiate a vhost-user-scmi device as part of a PCI bus.
It is mostly boilerplate similar to the other vhost-user-*-pci boilerplates
of similar devices.

Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
---
 hw/virtio/meson.build           |  1 +
 hw/virtio/vhost-user-scmi-pci.c | 68 +++++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+)
 create mode 100644 hw/virtio/vhost-user-scmi-pci.c

diff --git a/hw/virtio/meson.build b/hw/virtio/meson.build
index 4a4d7e1c27..c4f4fe05fa 100644
--- a/hw/virtio/meson.build
+++ b/hw/virtio/meson.build
@@ -36,6 +36,7 @@ specific_virtio_ss.add(when: 'CONFIG_VHOST_USER_RNG', if_true: files('vhost-user
 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'))
 
 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-scmi-pci.c b/hw/virtio/vhost-user-scmi-pci.c
new file mode 100644
index 0000000000..7f53af7fce
--- /dev/null
+++ b/hw/virtio/vhost-user-scmi-pci.c
@@ -0,0 +1,68 @@
+/*
+ * Vhost-user SCMI virtio device PCI glue
+ *
+ * SPDX-FileCopyrightText: Red Hat, Inc.
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "hw/qdev-properties.h"
+#include "hw/virtio/vhost-user-scmi.h"
+#include "hw/virtio/virtio-pci.h"
+
+struct VHostUserSCMIPCI {
+    VirtIOPCIProxy parent_obj;
+    VHostUserSCMI vdev;
+};
+
+typedef struct VHostUserSCMIPCI VHostUserSCMIPCI;
+
+#define TYPE_VHOST_USER_SCMI_PCI "vhost-user-scmi-pci-base"
+
+DECLARE_INSTANCE_CHECKER(VHostUserSCMIPCI, VHOST_USER_SCMI_PCI,
+                         TYPE_VHOST_USER_SCMI_PCI)
+
+static void vhost_user_scmi_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
+{
+    VHostUserSCMIPCI *dev = VHOST_USER_SCMI_PCI(vpci_dev);
+    DeviceState *vdev = DEVICE(&dev->vdev);
+
+    vpci_dev->nvectors = 1;
+    qdev_realize(vdev, BUS(&vpci_dev->bus), errp);
+}
+
+static void vhost_user_scmi_pci_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    VirtioPCIClass *k = VIRTIO_PCI_CLASS(klass);
+    PCIDeviceClass *pcidev_k = PCI_DEVICE_CLASS(klass);
+    k->realize = vhost_user_scmi_pci_realize;
+    set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
+    pcidev_k->vendor_id = PCI_VENDOR_ID_REDHAT_QUMRANET;
+    pcidev_k->device_id = 0; /* Set by virtio-pci based on virtio id */
+    pcidev_k->revision = 0x00;
+    pcidev_k->class_id = PCI_CLASS_COMMUNICATION_OTHER;
+}
+
+static void vhost_user_scmi_pci_instance_init(Object *obj)
+{
+    VHostUserSCMIPCI *dev = VHOST_USER_SCMI_PCI(obj);
+
+    virtio_instance_init_common(obj, &dev->vdev, sizeof(dev->vdev),
+                                TYPE_VHOST_USER_SCMI);
+}
+
+static const VirtioPCIDeviceTypeInfo vhost_user_scmi_pci_info = {
+    .base_name = TYPE_VHOST_USER_SCMI_PCI,
+    .non_transitional_name = "vhost-user-scmi-pci",
+    .instance_size = sizeof(VHostUserSCMIPCI),
+    .instance_init = vhost_user_scmi_pci_instance_init,
+    .class_init = vhost_user_scmi_pci_class_init,
+};
+
+static void vhost_user_scmi_pci_register(void)
+{
+    virtio_pci_types_register(&vhost_user_scmi_pci_info);
+}
+
+type_init(vhost_user_scmi_pci_register);
-- 
2.40.1

[PATCH v3 3/3] tests/qtest: enable tests for virtio-scmi

[Milan Zamazal]

We don't have a virtio-scmi implementation in QEMU and only support a
vhost-user backend.  This is very similar to virtio-gpio and we add the same
set of tests, just passing some vhost-user messages over the control socket.

Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Acked-by: Thomas Huth <thuth@redhat.com>
---
 MAINTAINERS                      |   1 +
 tests/qtest/libqos/meson.build   |   1 +
 tests/qtest/libqos/virtio-scmi.c | 174 +++++++++++++++++++++++++++++++
 tests/qtest/libqos/virtio-scmi.h |  34 ++++++
 tests/qtest/vhost-user-test.c    |  44 ++++++++
 5 files changed, 254 insertions(+)
 create mode 100644 tests/qtest/libqos/virtio-scmi.c
 create mode 100644 tests/qtest/libqos/virtio-scmi.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 7ddb8268fe..ad58de4df9 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2215,6 +2215,7 @@ R: mzamazal@redhat.com
 S: Supported
 F: hw/virtio/vhost-user-scmi*
 F: include/hw/virtio/vhost-user-scmi.h
+F: tests/qtest/libqos/virtio-scmi.*
 
 virtio-crypto
 M: Gonglei <arei.gonglei@huawei.com>
diff --git a/tests/qtest/libqos/meson.build b/tests/qtest/libqos/meson.build
index cc209a8de5..90aae42a22 100644
--- a/tests/qtest/libqos/meson.build
+++ b/tests/qtest/libqos/meson.build
@@ -46,6 +46,7 @@ libqos_srcs = files(
         'virtio-serial.c',
         'virtio-iommu.c',
         'virtio-gpio.c',
+        'virtio-scmi.c',
         'generic-pcihost.c',
 
         # qgraph machines:
diff --git a/tests/qtest/libqos/virtio-scmi.c b/tests/qtest/libqos/virtio-scmi.c
new file mode 100644
index 0000000000..ce8f4d5c06
--- /dev/null
+++ b/tests/qtest/libqos/virtio-scmi.c
@@ -0,0 +1,174 @@
+/*
+ * virtio-scmi nodes for testing
+ *
+ * SPDX-FileCopyrightText: Linaro Ltd
+ * SPDX-FileCopyrightText: Red Hat, Inc.
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * Based on virtio-gpio.c, doing basically the same thing.
+ */
+
+#include "qemu/osdep.h"
+#include "standard-headers/linux/virtio_config.h"
+#include "../libqtest.h"
+#include "qemu/module.h"
+#include "qgraph.h"
+#include "virtio-scmi.h"
+
+static QGuestAllocator *alloc;
+
+static void virtio_scmi_cleanup(QVhostUserSCMI *scmi)
+{
+    QVirtioDevice *vdev = scmi->vdev;
+    int i;
+
+    for (i = 0; i < 2; i++) {
+        qvirtqueue_cleanup(vdev->bus, scmi->queues[i], alloc);
+    }
+    g_free(scmi->queues);
+}
+
+/*
+ * This handles the VirtIO setup from the point of view of the driver
+ * frontend and therefore doesn't present any vhost specific features
+ * and in fact masks of the re-used bit.
+ */
+static void virtio_scmi_setup(QVhostUserSCMI *scmi)
+{
+    QVirtioDevice *vdev = scmi->vdev;
+    uint64_t features;
+    int i;
+
+    features = qvirtio_get_features(vdev);
+    features &= ~QVIRTIO_F_BAD_FEATURE;
+    qvirtio_set_features(vdev, features);
+
+    scmi->queues = g_new(QVirtQueue *, 2);
+    for (i = 0; i < 2; i++) {
+        scmi->queues[i] = qvirtqueue_setup(vdev, alloc, i);
+    }
+    qvirtio_set_driver_ok(vdev);
+}
+
+static void *qvirtio_scmi_get_driver(QVhostUserSCMI *v_scmi,
+                                     const char *interface)
+{
+    if (!g_strcmp0(interface, "vhost-user-scmi")) {
+        return v_scmi;
+    }
+    if (!g_strcmp0(interface, "virtio")) {
+        return v_scmi->vdev;
+    }
+
+    g_assert_not_reached();
+}
+
+static void *qvirtio_scmi_device_get_driver(void *object,
+                                            const char *interface)
+{
+    QVhostUserSCMIDevice *v_scmi = object;
+    return qvirtio_scmi_get_driver(&v_scmi->scmi, interface);
+}
+
+/* virtio-scmi (mmio) */
+static void qvirtio_scmi_device_destructor(QOSGraphObject *obj)
+{
+    QVhostUserSCMIDevice *scmi_dev = (QVhostUserSCMIDevice *) obj;
+    virtio_scmi_cleanup(&scmi_dev->scmi);
+}
+
+static void qvirtio_scmi_device_start_hw(QOSGraphObject *obj)
+{
+    QVhostUserSCMIDevice *scmi_dev = (QVhostUserSCMIDevice *) obj;
+    virtio_scmi_setup(&scmi_dev->scmi);
+}
+
+static void *virtio_scmi_device_create(void *virtio_dev,
+                                       QGuestAllocator *t_alloc,
+                                       void *addr)
+{
+    QVhostUserSCMIDevice *virtio_device = g_new0(QVhostUserSCMIDevice, 1);
+    QVhostUserSCMI *interface = &virtio_device->scmi;
+
+    interface->vdev = virtio_dev;
+    alloc = t_alloc;
+
+    virtio_device->obj.get_driver = qvirtio_scmi_device_get_driver;
+    virtio_device->obj.start_hw = qvirtio_scmi_device_start_hw;
+    virtio_device->obj.destructor = qvirtio_scmi_device_destructor;
+
+    return &virtio_device->obj;
+}
+
+/* virtio-scmi-pci */
+static void qvirtio_scmi_pci_destructor(QOSGraphObject *obj)
+{
+    QVhostUserSCMIPCI *scmi_pci = (QVhostUserSCMIPCI *) obj;
+    QOSGraphObject *pci_vobj =  &scmi_pci->pci_vdev.obj;
+
+    virtio_scmi_cleanup(&scmi_pci->scmi);
+    qvirtio_pci_destructor(pci_vobj);
+}
+
+static void qvirtio_scmi_pci_start_hw(QOSGraphObject *obj)
+{
+    QVhostUserSCMIPCI *scmi_pci = (QVhostUserSCMIPCI *) obj;
+    QOSGraphObject *pci_vobj =  &scmi_pci->pci_vdev.obj;
+
+    qvirtio_pci_start_hw(pci_vobj);
+    virtio_scmi_setup(&scmi_pci->scmi);
+}
+
+static void *qvirtio_scmi_pci_get_driver(void *object, const char *interface)
+{
+    QVhostUserSCMIPCI *v_scmi = object;
+
+    if (!g_strcmp0(interface, "pci-device")) {
+        return v_scmi->pci_vdev.pdev;
+    }
+    return qvirtio_scmi_get_driver(&v_scmi->scmi, interface);
+}
+
+static void *virtio_scmi_pci_create(void *pci_bus, QGuestAllocator *t_alloc,
+                                    void *addr)
+{
+    QVhostUserSCMIPCI *virtio_spci = g_new0(QVhostUserSCMIPCI, 1);
+    QVhostUserSCMI *interface = &virtio_spci->scmi;
+    QOSGraphObject *obj = &virtio_spci->pci_vdev.obj;
+
+    virtio_pci_init(&virtio_spci->pci_vdev, pci_bus, addr);
+    interface->vdev = &virtio_spci->pci_vdev.vdev;
+    alloc = t_alloc;
+
+    obj->get_driver = qvirtio_scmi_pci_get_driver;
+    obj->start_hw = qvirtio_scmi_pci_start_hw;
+    obj->destructor = qvirtio_scmi_pci_destructor;
+
+    return obj;
+}
+
+static void virtio_scmi_register_nodes(void)
+{
+    QPCIAddress addr = {
+        .devfn = QPCI_DEVFN(4, 0),
+    };
+
+    QOSGraphEdgeOptions edge_opts = { };
+
+    /* vhost-user-scmi-device */
+    edge_opts.extra_device_opts = "id=scmi,chardev=chr-vhost-user-test "
+        "-global virtio-mmio.force-legacy=false";
+    qos_node_create_driver("vhost-user-scmi-device",
+                            virtio_scmi_device_create);
+    qos_node_consumes("vhost-user-scmi-device", "virtio-bus", &edge_opts);
+    qos_node_produces("vhost-user-scmi-device", "vhost-user-scmi");
+
+    /* virtio-scmi-pci */
+    edge_opts.extra_device_opts = "id=scmi,addr=04.0,chardev=chr-vhost-user-test";
+    add_qpci_address(&edge_opts, &addr);
+    qos_node_create_driver("vhost-user-scmi-pci", virtio_scmi_pci_create);
+    qos_node_consumes("vhost-user-scmi-pci", "pci-bus", &edge_opts);
+    qos_node_produces("vhost-user-scmi-pci", "vhost-user-scmi");
+}
+
+libqos_init(virtio_scmi_register_nodes);
diff --git a/tests/qtest/libqos/virtio-scmi.h b/tests/qtest/libqos/virtio-scmi.h
new file mode 100644
index 0000000000..cb5670da6e
--- /dev/null
+++ b/tests/qtest/libqos/virtio-scmi.h
@@ -0,0 +1,34 @@
+/*
+ * virtio-scmi structures
+ *
+ * SPDX-FileCopyrightText: Red Hat, Inc.
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef TESTS_LIBQOS_VIRTIO_SCMI_H
+#define TESTS_LIBQOS_VIRTIO_SCMI_H
+
+#include "qgraph.h"
+#include "virtio.h"
+#include "virtio-pci.h"
+
+typedef struct QVhostUserSCMI QVhostUserSCMI;
+typedef struct QVhostUserSCMIPCI QVhostUserSCMIPCI;
+typedef struct QVhostUserSCMIDevice QVhostUserSCMIDevice;
+
+struct QVhostUserSCMI {
+    QVirtioDevice *vdev;
+    QVirtQueue **queues;
+};
+
+struct QVhostUserSCMIPCI {
+    QVirtioPCIDevice pci_vdev;
+    QVhostUserSCMI scmi;
+};
+
+struct QVhostUserSCMIDevice {
+    QOSGraphObject obj;
+    QVhostUserSCMI scmi;
+};
+
+#endif
diff --git a/tests/qtest/vhost-user-test.c b/tests/qtest/vhost-user-test.c
index dfb8003597..d4e437265f 100644
--- a/tests/qtest/vhost-user-test.c
+++ b/tests/qtest/vhost-user-test.c
@@ -33,6 +33,7 @@
 #include "standard-headers/linux/virtio_ids.h"
 #include "standard-headers/linux/virtio_net.h"
 #include "standard-headers/linux/virtio_gpio.h"
+#include "standard-headers/linux/virtio_scmi.h"
 
 #ifdef CONFIG_LINUX
 #include <sys/vfs.h>
@@ -145,6 +146,7 @@ enum {
 enum {
     VHOST_USER_NET,
     VHOST_USER_GPIO,
+    VHOST_USER_SCMI,
 };
 
 typedef struct TestServer {
@@ -1157,3 +1159,45 @@ static void register_vhost_gpio_test(void)
                  "vhost-user-gpio", test_read_guest_mem, &opts);
 }
 libqos_init(register_vhost_gpio_test);
+
+static uint64_t vu_scmi_get_features(TestServer *s)
+{
+    return 0x1ULL << VIRTIO_F_VERSION_1 |
+        0x1ULL << VIRTIO_SCMI_F_P2A_CHANNELS |
+        0x1ULL << VHOST_USER_F_PROTOCOL_FEATURES;
+}
+
+static void vu_scmi_get_protocol_features(TestServer *s, CharBackend *chr,
+                                          VhostUserMsg *msg)
+{
+    msg->flags |= VHOST_USER_REPLY_MASK;
+    msg->size = sizeof(m.payload.u64);
+    msg->payload.u64 = 1ULL << VHOST_USER_PROTOCOL_F_MQ;
+
+    qemu_chr_fe_write_all(chr, (uint8_t *)msg, VHOST_USER_HDR_SIZE + msg->size);
+}
+
+static struct vhost_user_ops g_vu_scmi_ops = {
+    .type = VHOST_USER_SCMI,
+
+    .append_opts = append_vhost_gpio_opts,
+
+    .get_features = vu_scmi_get_features,
+    .set_features = vu_net_set_features,
+    .get_protocol_features = vu_scmi_get_protocol_features,
+};
+
+static void register_vhost_scmi_test(void)
+{
+    QOSGraphTestOptions opts = {
+        .before = vhost_user_test_setup,
+        .subprocess = true,
+        .arg = &g_vu_scmi_ops,
+    };
+
+    qemu_add_opts(&qemu_chardev_opts);
+
+    qos_add_test("scmi/read-guest-mem/memfile",
+                 "vhost-user-scmi", test_read_guest_mem, &opts);
+}
+libqos_init(register_vhost_scmi_test);
-- 
2.40.1