@@ -45,7 +45,7 @@
#include "migration/qemu-file.h"
#include "sysemu/tpm.h"
-static QLIST_HEAD(, VFIOAddressSpace) vfio_address_spaces =
+VFIOAddressSpaceList vfio_address_spaces =
QLIST_HEAD_INITIALIZER(vfio_address_spaces);
#ifdef CONFIG_KVM
@@ -1520,8 +1520,16 @@ int vfio_attach_device(char *name, VFIODevice *vbasedev,
{
const VFIOIOMMUBackendOpsClass *ops;
- ops = VFIO_IOMMU_BACKEND_OPS_CLASS(
+#ifdef CONFIG_IOMMUFD
+ if (vbasedev->iommufd) {
+ ops = VFIO_IOMMU_BACKEND_OPS_CLASS(
+ object_class_by_name(TYPE_VFIO_IOMMU_BACKEND_IOMMUFD_OPS));
+ } else
+#endif
+ {
+ ops = VFIO_IOMMU_BACKEND_OPS_CLASS(
object_class_by_name(TYPE_VFIO_IOMMU_BACKEND_LEGACY_OPS));
+ }
if (!ops) {
error_setg(errp, "VFIO IOMMU Backend not found!");
return -ENODEV;
new file mode 100644
@@ -0,0 +1,521 @@
+/*
+ * iommufd container backend
+ *
+ * Copyright (C) 2023 Intel Corporation.
+ * Copyright Red Hat, Inc. 2023
+ *
+ * Authors: Yi Liu <yi.l.liu@intel.com>
+ * Eric Auger <eric.auger@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "qemu/osdep.h"
+#include <sys/ioctl.h>
+#include <linux/vfio.h>
+#include <linux/iommufd.h>
+
+#include "hw/vfio/vfio-common.h"
+#include "qemu/error-report.h"
+#include "trace.h"
+#include "qapi/error.h"
+#include "sysemu/iommufd.h"
+#include "hw/qdev-core.h"
+#include "sysemu/reset.h"
+#include "qemu/cutils.h"
+#include "qemu/char_dev.h"
+
+static int iommufd_map(VFIOContainer *bcontainer, hwaddr iova,
+ ram_addr_t size, void *vaddr, bool readonly)
+{
+ VFIOIOMMUFDContainer *container =
+ container_of(bcontainer, VFIOIOMMUFDContainer, bcontainer);
+
+ return iommufd_backend_map_dma(container->be,
+ container->ioas_id,
+ iova, size, vaddr, readonly);
+}
+
+static int iommufd_unmap(VFIOContainer *bcontainer,
+ hwaddr iova, ram_addr_t size,
+ IOMMUTLBEntry *iotlb)
+{
+ VFIOIOMMUFDContainer *container =
+ container_of(bcontainer, VFIOIOMMUFDContainer, bcontainer);
+
+ /* TODO: Handle dma_unmap_bitmap with iotlb args (migration) */
+ return iommufd_backend_unmap_dma(container->be,
+ container->ioas_id, iova, size);
+}
+
+static void vfio_kvm_device_add_device(VFIODevice *vbasedev)
+{
+ vfio_kvm_device_add_fd(vbasedev->fd);
+}
+
+static void vfio_kvm_device_del_device(VFIODevice *vbasedev)
+{
+ vfio_kvm_device_del_fd(vbasedev->fd);
+}
+
+static int iommufd_connect_and_bind(VFIODevice *vbasedev, Error **errp)
+{
+ IOMMUFDBackend *iommufd = vbasedev->iommufd;
+ struct vfio_device_bind_iommufd bind = {
+ .argsz = sizeof(bind),
+ .flags = 0,
+ };
+ int ret;
+
+ ret = iommufd_backend_connect(iommufd, errp);
+ if (ret) {
+ return ret;
+ }
+
+ /*
+ * Add device to kvm-vfio to be prepared for the tracking
+ * in KVM. Especially for some emulated devices, it requires
+ * to have kvm information in the device open.
+ */
+ vfio_kvm_device_add_device(vbasedev);
+
+ /* Bind device to iommufd */
+ bind.iommufd = iommufd->fd;
+ ret = ioctl(vbasedev->fd, VFIO_DEVICE_BIND_IOMMUFD, &bind);
+ if (ret) {
+ error_setg_errno(errp, errno, "error bind device fd=%d to iommufd=%d",
+ vbasedev->fd, bind.iommufd);
+ goto err_bind;
+ }
+
+ vbasedev->devid = bind.out_devid;
+ trace_vfio_iommufd_bind_device(bind.iommufd, vbasedev->name,
+ vbasedev->fd, vbasedev->devid);
+ return ret;
+err_bind:
+ vfio_kvm_device_del_device(vbasedev);
+ iommufd_backend_disconnect(iommufd);
+ return ret;
+}
+
+static void iommufd_unbind_and_disconnect(VFIODevice *vbasedev)
+{
+ /* Unbind is automatically conducted when device fd is closed */
+ vfio_kvm_device_del_device(vbasedev);
+ iommufd_backend_disconnect(vbasedev->iommufd);
+}
+
+static int vfio_get_devicefd(const char *sysfs_path, Error **errp)
+{
+ long int ret = -ENOTTY;
+ char *path, *vfio_dev_path = NULL, *vfio_path = NULL;
+ DIR *dir = NULL;
+ struct dirent *dent;
+ gchar *contents;
+ struct stat st;
+ gsize length;
+ int major, minor;
+ dev_t vfio_devt;
+
+ path = g_strdup_printf("%s/vfio-dev", sysfs_path);
+ if (stat(path, &st) < 0) {
+ error_setg_errno(errp, errno, "no such host device");
+ goto out_free_path;
+ }
+
+ dir = opendir(path);
+ if (!dir) {
+ error_setg_errno(errp, errno, "couldn't open dirrectory %s", path);
+ goto out_free_path;
+ }
+
+ while ((dent = readdir(dir))) {
+ if (!strncmp(dent->d_name, "vfio", 4)) {
+ vfio_dev_path = g_strdup_printf("%s/%s/dev", path, dent->d_name);
+ break;
+ }
+ }
+
+ if (!vfio_dev_path) {
+ error_setg(errp, "failed to find vfio-dev/vfioX/dev");
+ goto out_close_dir;
+ }
+
+ if (!g_file_get_contents(vfio_dev_path, &contents, &length, NULL)) {
+ error_setg(errp, "failed to load \"%s\"", vfio_dev_path);
+ goto out_free_dev_path;
+ }
+
+ if (sscanf(contents, "%d:%d", &major, &minor) != 2) {
+ error_setg(errp, "failed to get major:minor for \"%s\"", vfio_dev_path);
+ goto out_free_dev_path;
+ }
+ g_free(contents);
+ vfio_devt = makedev(major, minor);
+
+ vfio_path = g_strdup_printf("/dev/vfio/devices/%s", dent->d_name);
+ ret = open_cdev(vfio_path, vfio_devt);
+ if (ret < 0) {
+ error_setg(errp, "Failed to open %s", vfio_path);
+ }
+
+ trace_vfio_iommufd_get_devicefd(vfio_path, ret);
+ g_free(vfio_path);
+
+out_free_dev_path:
+ g_free(vfio_dev_path);
+out_close_dir:
+ closedir(dir);
+out_free_path:
+ if (*errp) {
+ error_prepend(errp, VFIO_MSG_PREFIX, path);
+ }
+ g_free(path);
+
+ return ret;
+}
+
+static VFIOIOASHwpt *vfio_container_get_hwpt(VFIOIOMMUFDContainer *container,
+ uint32_t hwpt_id)
+{
+ VFIOIOASHwpt *hwpt;
+
+ QLIST_FOREACH(hwpt, &container->hwpt_list, next) {
+ if (hwpt->hwpt_id == hwpt_id) {
+ return hwpt;
+ }
+ }
+
+ hwpt = g_malloc0(sizeof(*hwpt));
+
+ hwpt->hwpt_id = hwpt_id;
+ QLIST_INIT(&hwpt->device_list);
+ QLIST_INSERT_HEAD(&container->hwpt_list, hwpt, next);
+
+ return hwpt;
+}
+
+static void vfio_container_put_hwpt(IOMMUFDBackend *be, VFIOIOASHwpt *hwpt)
+{
+ QLIST_REMOVE(hwpt, next);
+ iommufd_backend_free_id(be->fd, hwpt->hwpt_id);
+ g_free(hwpt);
+}
+
+static int __vfio_device_attach_hwpt(VFIODevice *vbasedev, uint32_t hwpt_id,
+ Error **errp)
+{
+ struct vfio_device_attach_iommufd_pt attach_data = {
+ .argsz = sizeof(attach_data),
+ .flags = 0,
+ .pt_id = hwpt_id,
+ };
+ int ret;
+
+ ret = ioctl(vbasedev->fd, VFIO_DEVICE_ATTACH_IOMMUFD_PT, &attach_data);
+ if (ret) {
+ error_setg_errno(errp, errno,
+ "[iommufd=%d] error attach %s (%d) to hwpt_id=%d",
+ vbasedev->iommufd->fd, vbasedev->name, vbasedev->fd,
+ hwpt_id);
+ }
+ return ret;
+}
+
+static int __vfio_device_detach_hwpt(VFIODevice *vbasedev, Error **errp)
+{
+ struct vfio_device_detach_iommufd_pt detach_data = {
+ .argsz = sizeof(detach_data),
+ .flags = 0,
+ };
+ int ret;
+
+ ret = ioctl(vbasedev->fd, VFIO_DEVICE_DETACH_IOMMUFD_PT, &detach_data);
+ if (ret) {
+ error_setg_errno(errp, errno, "detach %s from ioas failed",
+ vbasedev->name);
+ }
+ return ret;
+}
+
+static int vfio_device_attach_container(VFIODevice *vbasedev,
+ VFIOIOMMUFDContainer *container,
+ Error **errp)
+{
+ int ret, iommufd = vbasedev->iommufd->fd;
+ VFIOIOASHwpt *hwpt;
+ uint32_t hwpt_id;
+ Error *err = NULL;
+
+ /* try to attach to an existing hwpt in this container */
+ QLIST_FOREACH(hwpt, &container->hwpt_list, next) {
+ ret = __vfio_device_attach_hwpt(vbasedev, hwpt->hwpt_id, &err);
+ if (ret) {
+ const char *msg = error_get_pretty(err);
+
+ trace_vfio_iommufd_fail_attach_existing_hwpt(msg);
+ error_free(err);
+ err = NULL;
+ } else {
+ goto found_hwpt;
+ }
+ }
+
+ ret = iommufd_backend_alloc_hwpt(iommufd, vbasedev->devid,
+ container->ioas_id, &hwpt_id);
+
+ if (ret) {
+ error_setg_errno(errp, errno, "error alloc shadow hwpt");
+ return ret;
+ }
+
+ /* Attach device to an hwpt within iommufd */
+ ret = __vfio_device_attach_hwpt(vbasedev, hwpt_id, errp);
+ if (ret) {
+ iommufd_backend_free_id(iommufd, hwpt_id);
+ return ret;
+ }
+
+ hwpt = vfio_container_get_hwpt(container, hwpt_id);
+found_hwpt:
+ QLIST_INSERT_HEAD(&hwpt->device_list, vbasedev, next);
+ vbasedev->hwpt = hwpt;
+
+ trace_vfio_iommufd_attach_device(iommufd, vbasedev->name, vbasedev->fd,
+ container->ioas_id, hwpt->hwpt_id);
+ return ret;
+}
+
+static void vfio_device_detach_container(VFIODevice *vbasedev,
+ VFIOIOMMUFDContainer *container,
+ Error **errp)
+{
+ VFIOIOASHwpt *hwpt = vbasedev->hwpt;
+
+ __vfio_device_detach_hwpt(vbasedev, errp);
+ QLIST_REMOVE(vbasedev, next);
+ vbasedev->hwpt = NULL;
+ if (QLIST_EMPTY(&hwpt->device_list)) {
+ vfio_container_put_hwpt(vbasedev->iommufd, hwpt);
+ }
+
+ trace_vfio_iommufd_detach_device(container->be->fd, vbasedev->name,
+ container->ioas_id);
+}
+
+static void vfio_iommufd_container_destroy(VFIOIOMMUFDContainer *container)
+{
+ VFIOContainer *bcontainer = &container->bcontainer;
+
+ if (!QLIST_EMPTY(&container->hwpt_list)) {
+ return;
+ }
+ memory_listener_unregister(&bcontainer->listener);
+ vfio_container_destroy(bcontainer);
+ iommufd_backend_put_ioas(container->be, container->ioas_id);
+ g_free(container);
+}
+
+static int vfio_ram_block_discard_disable(bool state)
+{
+ /*
+ * We support coordinated discarding of RAM via the RamDiscardManager.
+ */
+ return ram_block_uncoordinated_discard_disable(state);
+}
+
+static int iommufd_attach_device(char *name, VFIODevice *vbasedev,
+ AddressSpace *as, Error **errp)
+{
+ VFIOIOMMUBackendOpsClass *ops = VFIO_IOMMU_BACKEND_OPS_CLASS(
+ object_class_by_name(TYPE_VFIO_IOMMU_BACKEND_IOMMUFD_OPS));
+ VFIOContainer *bcontainer;
+ VFIOIOMMUFDContainer *container;
+ VFIOAddressSpace *space;
+ struct vfio_device_info dev_info = { .argsz = sizeof(dev_info) };
+ int ret, devfd;
+ uint32_t ioas_id;
+ Error *err = NULL;
+
+ devfd = vfio_get_devicefd(vbasedev->sysfsdev, errp);
+ if (devfd < 0) {
+ return devfd;
+ }
+ vbasedev->fd = devfd;
+
+ ret = iommufd_connect_and_bind(vbasedev, errp);
+ if (ret) {
+ goto err_connect_bind;
+ }
+
+ space = vfio_get_address_space(as);
+
+ /* try to attach to an existing container in this space */
+ QLIST_FOREACH(bcontainer, &space->containers, next) {
+ container = container_of(bcontainer, VFIOIOMMUFDContainer, bcontainer);
+ if (bcontainer->ops != ops || vbasedev->iommufd != container->be) {
+ continue;
+ }
+ if (vfio_device_attach_container(vbasedev, container, &err)) {
+ const char *msg = error_get_pretty(err);
+
+ trace_vfio_iommufd_fail_attach_existing_container(msg);
+ error_free(err);
+ err = NULL;
+ } else {
+ ret = vfio_ram_block_discard_disable(true);
+ if (ret) {
+ error_setg(errp,
+ "Cannot set discarding of RAM broken (%d)", ret);
+ goto err_discard_disable;
+ }
+ goto found_container;
+ }
+ }
+
+ /* Need to allocate a new dedicated container */
+ ret = iommufd_backend_get_ioas(vbasedev->iommufd, &ioas_id);
+ if (ret < 0) {
+ error_setg_errno(errp, errno, "Failed to alloc ioas");
+ goto err_get_ioas;
+ }
+
+ trace_vfio_iommufd_alloc_ioas(vbasedev->iommufd->fd, ioas_id);
+
+ container = g_malloc0(sizeof(*container));
+ container->be = vbasedev->iommufd;
+ container->ioas_id = ioas_id;
+ QLIST_INIT(&container->hwpt_list);
+
+ bcontainer = &container->bcontainer;
+ vfio_container_init(bcontainer, space, ops);
+
+ ret = vfio_device_attach_container(vbasedev, container, errp);
+ if (ret) {
+ goto err_attach_container;
+ }
+
+ ret = vfio_ram_block_discard_disable(true);
+ if (ret) {
+ goto err_discard_disable;
+ }
+
+ /*
+ * TODO: for now iommufd BE is on par with vfio iommu type1, so it's
+ * fine to add the whole range as window. For SPAPR, below code
+ * should be updated.
+ */
+ vfio_host_win_add(bcontainer, 0, (hwaddr)-1, 4096);
+ bcontainer->pgsizes = 4096;
+
+ QLIST_INSERT_HEAD(&space->containers, bcontainer, next);
+
+ bcontainer->listener = vfio_memory_listener;
+
+ memory_listener_register(&bcontainer->listener, bcontainer->space->as);
+
+ bcontainer->initialized = true;
+
+found_container:
+ /*
+ * TODO: examine RAM_BLOCK_DISCARD stuff, should we do group level
+ * for discarding incompatibility check as well?
+ */
+ if (vbasedev->ram_block_discard_allowed) {
+ vfio_ram_block_discard_disable(false);
+ }
+
+ ret = ioctl(devfd, VFIO_DEVICE_GET_INFO, &dev_info);
+ if (ret) {
+ error_setg_errno(errp, errno, "error getting device info");
+ goto err_discard_disable;
+ }
+
+ vbasedev->group = 0;
+ vbasedev->num_irqs = dev_info.num_irqs;
+ vbasedev->num_regions = dev_info.num_regions;
+ vbasedev->flags = dev_info.flags;
+ vbasedev->reset_works = !!(dev_info.flags & VFIO_DEVICE_FLAGS_RESET);
+ vbasedev->container = bcontainer;
+
+ trace_vfio_iommufd_device_info(vbasedev->name, devfd, vbasedev->num_irqs,
+ vbasedev->num_regions, vbasedev->flags);
+ return 0;
+
+err_discard_disable:
+ vfio_device_detach_container(vbasedev, container, &err);
+ if (err) {
+ error_report_err(err);
+ }
+err_attach_container:
+ vfio_iommufd_container_destroy(container);
+err_get_ioas:
+ vfio_put_address_space(space);
+ iommufd_unbind_and_disconnect(vbasedev);
+err_connect_bind:
+ close(vbasedev->fd);
+ return ret;
+}
+
+static void iommufd_detach_device(VFIODevice *vbasedev)
+{
+ VFIOContainer *bcontainer = vbasedev->container;
+ VFIOIOMMUFDContainer *container;
+ VFIOAddressSpace *space = bcontainer->space;
+ Error *err = NULL;
+
+ if (!bcontainer) {
+ return;
+ }
+
+ if (!vbasedev->ram_block_discard_allowed) {
+ vfio_ram_block_discard_disable(false);
+ }
+
+ container = container_of(bcontainer, VFIOIOMMUFDContainer, bcontainer);
+ vfio_device_detach_container(vbasedev, container, &err);
+ if (err) {
+ error_report_err(err);
+ }
+ if (QLIST_EMPTY(&container->hwpt_list)) {
+ vfio_iommufd_container_destroy(container);
+ vfio_put_address_space(space);
+ }
+ vbasedev->container = NULL;
+ iommufd_unbind_and_disconnect(vbasedev);
+ close(vbasedev->fd);
+}
+
+static void vfio_iommu_backend_iommufd_ops_class_init(ObjectClass *oc,
+ void *data) {
+ VFIOIOMMUBackendOpsClass *ops = VFIO_IOMMU_BACKEND_OPS_CLASS(oc);
+
+ ops->dma_map = iommufd_map;
+ ops->dma_unmap = iommufd_unmap;
+ ops->attach_device = iommufd_attach_device;
+ ops->detach_device = iommufd_detach_device;
+}
+
+static const TypeInfo vfio_iommu_backend_iommufd_ops_type = {
+ .name = TYPE_VFIO_IOMMU_BACKEND_IOMMUFD_OPS,
+
+ .parent = TYPE_VFIO_IOMMU_BACKEND_OPS,
+ .class_init = vfio_iommu_backend_iommufd_ops_class_init,
+ .abstract = true,
+};
+static void vfio_iommu_backend_iommufd_ops_register_types(void)
+{
+ type_register_static(&vfio_iommu_backend_iommufd_ops_type);
+}
+type_init(vfio_iommu_backend_iommufd_ops_register_types);
@@ -7,6 +7,9 @@ vfio_ss.add(files(
'spapr.c',
'migration.c',
))
+if have_iommufd
+ vfio_ss.add(files('iommufd.c'))
+endif
vfio_ss.add(when: 'CONFIG_VFIO_PCI', if_true: files(
'display.c',
'pci-quirks.c',
@@ -167,3 +167,15 @@ vfio_save_setup(const char *name, uint64_t data_buffer_size) " (%s) data buffer
vfio_state_pending_estimate(const char *name, uint64_t precopy, uint64_t postcopy, uint64_t precopy_init_size, uint64_t precopy_dirty_size) " (%s) precopy 0x%"PRIx64" postcopy 0x%"PRIx64" precopy initial size 0x%"PRIx64" precopy dirty size 0x%"PRIx64
vfio_state_pending_exact(const char *name, uint64_t precopy, uint64_t postcopy, uint64_t stopcopy_size, uint64_t precopy_init_size, uint64_t precopy_dirty_size) " (%s) precopy 0x%"PRIx64" postcopy 0x%"PRIx64" stopcopy size 0x%"PRIx64" precopy initial size 0x%"PRIx64" precopy dirty size 0x%"PRIx64
vfio_vmstate_change(const char *name, int running, const char *reason, const char *dev_state) " (%s) running %d reason %s device state %s"
+
+#iommufd.c
+
+vfio_iommufd_get_devicefd(const char *dev, int devfd) " %s (fd=%d)"
+vfio_iommufd_bind_device(int iommufd, const char *name, int devfd, int devid) " [iommufd=%d] Successfully bound device %s (fd=%d): output devid=%d"
+vfio_iommufd_fail_attach_existing_hwpt(const char *msg) " %s"
+vfio_iommufd_attach_device(int iommufd, const char *name, int devfd, int ioasid, int hwptid) " [iommufd=%d] Successfully attached device %s (%d) to ioasid=%d: output hwptd=%d"
+vfio_iommufd_detach_device(int iommufd, const char *name, int ioasid) " [iommufd=%d] Detached %s from ioasid=%d"
+vfio_iommufd_alloc_ioas(int iommufd, int ioas_id) " [iommufd=%d] new IOMMUFD container with ioasid=%d"
+vfio_iommufd_device_info(char *name, int devfd, int num_irqs, int num_regions, int flags) " %s (%d) num_irqs=%d num_regions=%d flags=%d"
+vfio_iommufd_fail_attach_existing_container(const char *msg) " %s"
+vfio_iommufd_container_reset(char *name) " Successfully reset %s"
@@ -85,6 +85,26 @@ typedef struct VFIOLegacyContainer {
QLIST_HEAD(, VFIOGroup) group_list;
} VFIOLegacyContainer;
+#ifdef CONFIG_IOMMUFD
+typedef struct VFIOIOASHwpt {
+ uint32_t hwpt_id;
+ QLIST_HEAD(, VFIODevice) device_list;
+ QLIST_ENTRY(VFIOIOASHwpt) next;
+} VFIOIOASHwpt;
+
+typedef struct IOMMUFDBackend IOMMUFDBackend;
+
+typedef struct VFIOIOMMUFDContainer {
+ VFIOContainer bcontainer;
+ IOMMUFDBackend *be;
+ uint32_t ioas_id;
+ QLIST_HEAD(, VFIOIOASHwpt) hwpt_list;
+} VFIOIOMMUFDContainer;
+#endif
+
+typedef QLIST_HEAD(VFIOAddressSpaceList, VFIOAddressSpace) VFIOAddressSpaceList;
+extern VFIOAddressSpaceList vfio_address_spaces;
+
typedef struct VFIODeviceOps VFIODeviceOps;
typedef struct VFIODevice {
@@ -110,6 +130,11 @@ typedef struct VFIODevice {
OnOffAuto pre_copy_dirty_page_tracking;
bool dirty_pages_supported;
bool dirty_tracking;
+#ifdef CONFIG_IOMMUFD
+ int devid;
+ VFIOIOASHwpt *hwpt;
+ IOMMUFDBackend *iommufd;
+#endif
} VFIODevice;
struct VFIODeviceOps {
@@ -117,6 +117,9 @@ void vfio_container_init(VFIOContainer *container,
void vfio_container_destroy(VFIOContainer *container);
#define TYPE_VFIO_IOMMU_BACKEND_LEGACY_OPS "vfio-iommu-backend-legacy-ops"
+#ifdef CONFIG_IOMMUFD
+#define TYPE_VFIO_IOMMU_BACKEND_IOMMUFD_OPS "vfio-iommu-backend-iommufd-ops"
+#endif
#define TYPE_VFIO_IOMMU_BACKEND_OPS "vfio-iommu-backend-ops"
DECLARE_CLASS_CHECKERS(VFIOIOMMUBackendOpsClass,