vfio/iommufd: register container for cpr

Register a vfio iommufd container and device for CPR, replacing the generic
CPR register call with a more specific iommufd register call.  Add a
blocker if the kernel does not support IOMMU_IOAS_CHANGE_PROCESS.

This is mostly boiler plate.  The fields to to saved and restored are added
in subsequent patches.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Link: https://lore.kernel.org/qemu-devel/1751493538-202042-13-git-send-email-steven.sistare@oracle.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

Author: Steve Sistare

backends/iommufd.c

@@ -108,6 +108,13 @@ bool iommufd_backend_connect(IOMMUFDBackend *be, Error **errp)
         }
         be->fd = fd;
     }
+    if (!be->users && !vfio_iommufd_cpr_register_iommufd(be, errp)) {
+        if (be->owned) {
+            close(be->fd);
+            be->fd = -1;
+        }
+        return false;
+    }
     be->users++;
 
     trace_iommufd_backend_connect(be->fd, be->owned, be->users);
@@ -125,6 +132,9 @@ void iommufd_backend_disconnect(IOMMUFDBackend *be)
         be->fd = -1;
     }
 out:
+    if (!be->users) {
+        vfio_iommufd_cpr_unregister_iommufd(be);
+    }
     trace_iommufd_backend_disconnect(be->fd, be->users);
 }
 

hw/vfio/cpr-iommufd.c

@@ -0,0 +1,86 @@
+/*
+ * Copyright (c) 2024-2025 Oracle and/or its affiliates.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "hw/vfio/vfio-cpr.h"
+#include "migration/blocker.h"
+#include "migration/cpr.h"
+#include "migration/migration.h"
+#include "migration/vmstate.h"
+#include "system/iommufd.h"
+#include "vfio-iommufd.h"
+
+static bool vfio_cpr_supported(IOMMUFDBackend *be, Error **errp)
+{
+    if (!iommufd_change_process_capable(be)) {
+        if (errp) {
+            error_setg(errp, "vfio iommufd backend does not support "
+                       "IOMMU_IOAS_CHANGE_PROCESS");
+        }
+        return false;
+    }
+    return true;
+}
+
+static const VMStateDescription iommufd_cpr_vmstate = {
+    .name = "iommufd",
+    .version_id = 0,
+    .minimum_version_id = 0,
+    .needed = cpr_incoming_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+bool vfio_iommufd_cpr_register_iommufd(IOMMUFDBackend *be, Error **errp)
+{
+    Error **cpr_blocker = &be->cpr_blocker;
+
+    if (!vfio_cpr_supported(be, cpr_blocker)) {
+        return migrate_add_blocker_modes(cpr_blocker, errp,
+                                         MIG_MODE_CPR_TRANSFER, -1) == 0;
+    }
+
+    vmstate_register(NULL, -1, &iommufd_cpr_vmstate, be);
+
+    return true;
+}
+
+void vfio_iommufd_cpr_unregister_iommufd(IOMMUFDBackend *be)
+{
+    vmstate_unregister(NULL, &iommufd_cpr_vmstate, be);
+    migrate_del_blocker(&be->cpr_blocker);
+}
+
+bool vfio_iommufd_cpr_register_container(VFIOIOMMUFDContainer *container,
+                                         Error **errp)
+{
+    VFIOContainerBase *bcontainer = &container->bcontainer;
+
+    migration_add_notifier_mode(&bcontainer->cpr_reboot_notifier,
+                                vfio_cpr_reboot_notifier,
+                                MIG_MODE_CPR_REBOOT);
+
+    vfio_cpr_add_kvm_notifier();
+
+    return true;
+}
+
+void vfio_iommufd_cpr_unregister_container(VFIOIOMMUFDContainer *container)
+{
+    VFIOContainerBase *bcontainer = &container->bcontainer;
+
+    migration_remove_notifier(&bcontainer->cpr_reboot_notifier);
+}
+
+void vfio_iommufd_cpr_register_device(VFIODevice *vbasedev)
+{
+}
+
+void vfio_iommufd_cpr_unregister_device(VFIODevice *vbasedev)
+{
+}

hw/vfio/iommufd.c

@@ -446,7 +446,7 @@ static void iommufd_cdev_container_destroy(VFIOIOMMUFDContainer *container)
     if (!QLIST_EMPTY(&bcontainer->device_list)) {
         return;
     }
-    vfio_cpr_unregister_container(bcontainer);
+    vfio_iommufd_cpr_unregister_container(container);
     vfio_listener_unregister(bcontainer);
     iommufd_backend_free_id(container->be, container->ioas_id);
     object_unref(container);
@@ -592,7 +592,7 @@ static bool iommufd_cdev_attach(const char *name, VFIODevice *vbasedev,
         goto err_listener_register;
     }
 
-    if (!vfio_cpr_register_container(bcontainer, errp)) {
+    if (!vfio_iommufd_cpr_register_container(container, errp)) {
         goto err_listener_register;
     }
 
@@ -623,6 +623,7 @@ static bool iommufd_cdev_attach(const char *name, VFIODevice *vbasedev,
     }
 
     vfio_device_prepare(vbasedev, bcontainer, &dev_info);
+    vfio_iommufd_cpr_register_device(vbasedev);
 
     trace_iommufd_cdev_device_info(vbasedev->name, devfd, vbasedev->num_irqs,
                                    vbasedev->num_regions, vbasedev->flags);
@@ -660,6 +661,7 @@ static void iommufd_cdev_detach(VFIODevice *vbasedev)
     iommufd_cdev_container_destroy(container);
     vfio_address_space_put(space);
 
+    vfio_iommufd_cpr_unregister_device(vbasedev);
     iommufd_cdev_unbind_and_disconnect(vbasedev);
     close(vbasedev->fd);
 }

hw/vfio/meson.build

@@ -31,6 +31,7 @@ system_ss.add(when: 'CONFIG_VFIO', if_true: files(
 ))
 system_ss.add(when: ['CONFIG_VFIO', 'CONFIG_IOMMUFD'], if_true: files(
   'iommufd.c',
+  'cpr-iommufd.c',
 ))
 system_ss.add(when: 'CONFIG_VFIO_PCI', if_true: files(
   'display.c',

include/hw/vfio/vfio-cpr.h

@@ -15,7 +15,10 @@
 struct VFIOContainer;
 struct VFIOContainerBase;
 struct VFIOGroup;
+struct VFIODevice;
 struct VFIOPCIDevice;
+struct VFIOIOMMUFDContainer;
+struct IOMMUFDBackend;
 
 typedef int (*dma_map_fn)(const struct VFIOContainerBase *bcontainer,
                           hwaddr iova, ram_addr_t size, void *vaddr,
@@ -44,6 +47,15 @@ bool vfio_cpr_register_container(struct VFIOContainerBase *bcontainer,
                                  Error **errp);
 void vfio_cpr_unregister_container(struct VFIOContainerBase *bcontainer);
 
+bool vfio_iommufd_cpr_register_container(struct VFIOIOMMUFDContainer *container,
+                                         Error **errp);
+void vfio_iommufd_cpr_unregister_container(
+    struct VFIOIOMMUFDContainer *container);
+bool vfio_iommufd_cpr_register_iommufd(struct IOMMUFDBackend *be, Error **errp);
+void vfio_iommufd_cpr_unregister_iommufd(struct IOMMUFDBackend *be);
+void vfio_iommufd_cpr_register_device(struct VFIODevice *vbasedev);
+void vfio_iommufd_cpr_unregister_device(struct VFIODevice *vbasedev);
+
 int vfio_cpr_group_get_device_fd(int d, const char *name);
 
 bool vfio_cpr_container_match(struct VFIOContainer *container,

include/system/iommufd.h

@@ -32,6 +32,7 @@ struct IOMMUFDBackend {
     /*< protected >*/
     int fd;            /* /dev/iommu file descriptor */
     bool owned;        /* is the /dev/iommu opened internally */
+    Error *cpr_blocker;/* set if be does not support CPR */
     uint32_t users;
 
     /*< public >*/