On 5/23/22 4:41 PM, Alex Williamson wrote:
>
> Hi Zhi & Zhenyu,
>
> Please review gvt changes below, I'd prefer to get your ack included.
> Thanks!
>
> Alex
>
> On Thu, 19 May 2022 14:33:11 -0400
> Matthew Rosato <mjrosato@xxxxxxxxxxxxx> wrote:
>
>> Rather than relying on a notifier for associating the KVM with
>> the group, let's assume that the association has already been
>> made prior to device_open. The first time a device is opened
>> associate the group KVM with the device.
>>
>> This fixes a user-triggerable oops in GVT.
>>
>> Reviewed-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
>> Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
>> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
>> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
>> Signed-off-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
>> ---
>> drivers/gpu/drm/i915/gvt/gtt.c | 4 +-
>> drivers/gpu/drm/i915/gvt/gvt.h | 3 -
>> drivers/gpu/drm/i915/gvt/kvmgt.c | 82 ++++++--------------------
>> drivers/s390/crypto/vfio_ap_ops.c | 35 ++---------
>> drivers/s390/crypto/vfio_ap_private.h | 3 -
>> drivers/vfio/vfio.c | 83 ++++++++++-----------------
>> include/linux/vfio.h | 6 +-
>> 7 files changed, 57 insertions(+), 159 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
>> index 9c5cc2800975..b4f69364f9a1 100644
>> --- a/drivers/gpu/drm/i915/gvt/gtt.c
>> +++ b/drivers/gpu/drm/i915/gvt/gtt.c
>> @@ -51,7 +51,7 @@ static int preallocated_oos_pages = 8192;
>>
>> static bool intel_gvt_is_valid_gfn(struct intel_vgpu *vgpu, unsigned long gfn)
>> {
>> - struct kvm *kvm = vgpu->kvm;
>> + struct kvm *kvm = vgpu->vfio_device.kvm;
>> int idx;
>> bool ret;
>>
>> @@ -1185,7 +1185,7 @@ static int is_2MB_gtt_possible(struct intel_vgpu *vgpu,
>>
>> if (!vgpu->attached)
>> return -EINVAL;
>> - pfn = gfn_to_pfn(vgpu->kvm, ops->get_pfn(entry));
>> + pfn = gfn_to_pfn(vgpu->vfio_device.kvm, ops->get_pfn(entry));
>> if (is_error_noslot_pfn(pfn))
>> return -EINVAL;
>> return PageTransHuge(pfn_to_page(pfn));
>> diff --git a/drivers/gpu/drm/i915/gvt/gvt.h b/drivers/gpu/drm/i915/gvt/gvt.h
>> index 2af4c83e733c..aee1a45da74b 100644
>> --- a/drivers/gpu/drm/i915/gvt/gvt.h
>> +++ b/drivers/gpu/drm/i915/gvt/gvt.h
>> @@ -227,9 +227,6 @@ struct intel_vgpu {
>> struct mutex cache_lock;
>>
>> struct notifier_block iommu_notifier;
>> - struct notifier_block group_notifier;
>> - struct kvm *kvm;
>> - struct work_struct release_work;
>> atomic_t released;
>>
>> struct kvm_page_track_notifier_node track_node;
>> diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
>> index 7655ffa97d51..e2f6c56ab342 100644
>> --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
>> +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
>> @@ -228,8 +228,6 @@ static void intel_gvt_cleanup_vgpu_type_groups(struct intel_gvt *gvt)
>> }
>> }
>>
>> -static void intel_vgpu_release_work(struct work_struct *work);
>> -
>> static void gvt_unpin_guest_page(struct intel_vgpu *vgpu, unsigned long gfn,
>> unsigned long size)
>> {
>> @@ -761,23 +759,6 @@ static int intel_vgpu_iommu_notifier(struct notifier_block *nb,
>> return NOTIFY_OK;
>> }
>>
>> -static int intel_vgpu_group_notifier(struct notifier_block *nb,
>> - unsigned long action, void *data)
>> -{
>> - struct intel_vgpu *vgpu =
>> - container_of(nb, struct intel_vgpu, group_notifier);
>> -
>> - /* the only action we care about */
>> - if (action == VFIO_GROUP_NOTIFY_SET_KVM) {
>> - vgpu->kvm = data;
>> -
>> - if (!data)
>> - schedule_work(&vgpu->release_work);
>> - }
>> -
>> - return NOTIFY_OK;
>> -}
>> -
>> static bool __kvmgt_vgpu_exist(struct intel_vgpu *vgpu)
>> {
>> struct intel_vgpu *itr;
>> @@ -789,7 +770,7 @@ static bool __kvmgt_vgpu_exist(struct intel_vgpu *vgpu)
>> if (!itr->attached)
>> continue;
>>
>> - if (vgpu->kvm == itr->kvm) {
>> + if (vgpu->vfio_device.kvm == itr->vfio_device.kvm) {
>> ret = true;
>> goto out;
>> }
>> @@ -806,7 +787,6 @@ static int intel_vgpu_open_device(struct vfio_device *vfio_dev)
>> int ret;
>>
>> vgpu->iommu_notifier.notifier_call = intel_vgpu_iommu_notifier;
>> - vgpu->group_notifier.notifier_call = intel_vgpu_group_notifier;
>>
>> events = VFIO_IOMMU_NOTIFY_DMA_UNMAP;
>> ret = vfio_register_notifier(vfio_dev, VFIO_IOMMU_NOTIFY, &events,
>> @@ -817,38 +797,32 @@ static int intel_vgpu_open_device(struct vfio_device *vfio_dev)
>> goto out;
>> }
>>
>> - events = VFIO_GROUP_NOTIFY_SET_KVM;
>> - ret = vfio_register_notifier(vfio_dev, VFIO_GROUP_NOTIFY, &events,
>> - &vgpu->group_notifier);
>> - if (ret != 0) {
>> - gvt_vgpu_err("vfio_register_notifier for group failed: %d\n",
>> - ret);
>> - goto undo_iommu;
>> - }
>> -
>> ret = -EEXIST;
>> if (vgpu->attached)
>> - goto undo_register;
>> + goto undo_iommu;
>>
>> ret = -ESRCH;
>> - if (!vgpu->kvm || vgpu->kvm->mm != current->mm) {
>> + if (!vgpu->vfio_device.kvm ||
>> + vgpu->vfio_device.kvm->mm != current->mm) {
>> gvt_vgpu_err("KVM is required to use Intel vGPU\n");
>> - goto undo_register;
>> + goto undo_iommu;
>> }
>>
>> + kvm_get_kvm(vgpu->vfio_device.kvm);
>> +
>> ret = -EEXIST;
>> if (__kvmgt_vgpu_exist(vgpu))
>> - goto undo_register;
>> + goto undo_iommu;
>>
>> vgpu->attached = true;
>> - kvm_get_kvm(vgpu->kvm);
>>
>> kvmgt_protect_table_init(vgpu);
>> gvt_cache_init(vgpu);
>>
>> vgpu->track_node.track_write = kvmgt_page_track_write;
>> vgpu->track_node.track_flush_slot = kvmgt_page_track_flush_slot;
>> - kvm_page_track_register_notifier(vgpu->kvm, &vgpu->track_node);
>> + kvm_page_track_register_notifier(vgpu->vfio_device.kvm,
>> + &vgpu->track_node);
>>
>> debugfs_create_ulong(KVMGT_DEBUGFS_FILENAME, 0444, vgpu->debugfs,
>> &vgpu->nr_cache_entries);
>> @@ -858,10 +832,6 @@ static int intel_vgpu_open_device(struct vfio_device *vfio_dev)
>> atomic_set(&vgpu->released, 0);
>> return 0;
>>
>> -undo_register:
>> - vfio_unregister_notifier(vfio_dev, VFIO_GROUP_NOTIFY,
>> - &vgpu->group_notifier);
>> -
>> undo_iommu:
>> vfio_unregister_notifier(vfio_dev, VFIO_IOMMU_NOTIFY,
>> &vgpu->iommu_notifier);
>> @@ -880,8 +850,9 @@ static void intel_vgpu_release_msi_eventfd_ctx(struct intel_vgpu *vgpu)
>> }
>> }
>>
>> -static void __intel_vgpu_release(struct intel_vgpu *vgpu)
>> +static void intel_vgpu_close_device(struct vfio_device *vfio_dev)
>> {
>> + struct intel_vgpu *vgpu = vfio_dev_to_vgpu(vfio_dev);
>> struct drm_i915_private *i915 = vgpu->gvt->gt->i915;
>> int ret;
>>
>> @@ -898,35 +869,19 @@ static void __intel_vgpu_release(struct intel_vgpu *vgpu)
>> drm_WARN(&i915->drm, ret,
>> "vfio_unregister_notifier for iommu failed: %d\n", ret);
>>
>> - ret = vfio_unregister_notifier(&vgpu->vfio_device, VFIO_GROUP_NOTIFY,
>> - &vgpu->group_notifier);
>> - drm_WARN(&i915->drm, ret,
>> - "vfio_unregister_notifier for group failed: %d\n", ret);
>> -
>> debugfs_remove(debugfs_lookup(KVMGT_DEBUGFS_FILENAME, vgpu->debugfs));
>>
>> - kvm_page_track_unregister_notifier(vgpu->kvm, &vgpu->track_node);
>> - kvm_put_kvm(vgpu->kvm);
>> + kvm_page_track_unregister_notifier(vgpu->vfio_device.kvm,
>> + &vgpu->track_node);
>> kvmgt_protect_table_destroy(vgpu);
>> gvt_cache_destroy(vgpu);
>>
>> intel_vgpu_release_msi_eventfd_ctx(vgpu);
>>
>> - vgpu->kvm = NULL;
>> vgpu->attached = false;
>> -}
>> -
>> -static void intel_vgpu_close_device(struct vfio_device *vfio_dev)
>> -{
>> - __intel_vgpu_release(vfio_dev_to_vgpu(vfio_dev));
>> -}
>> -
>> -static void intel_vgpu_release_work(struct work_struct *work)
>> -{
>> - struct intel_vgpu *vgpu =
>> - container_of(work, struct intel_vgpu, release_work);
>>
>> - __intel_vgpu_release(vgpu);
>> + if (vgpu->vfio_device.kvm)
>> + kvm_put_kvm(vgpu->vfio_device.kvm);
>> }
>>
>> static u64 intel_vgpu_get_bar_addr(struct intel_vgpu *vgpu, int bar)
>> @@ -1675,7 +1630,6 @@ static int intel_vgpu_probe(struct mdev_device *mdev)
>> return PTR_ERR(vgpu);
>> }
>>
>> - INIT_WORK(&vgpu->release_work, intel_vgpu_release_work);
>> vfio_init_group_dev(&vgpu->vfio_device, &mdev->dev,
>> &intel_vgpu_dev_ops);
>>
>> @@ -1713,7 +1667,7 @@ static struct mdev_driver intel_vgpu_mdev_driver = {
>>
>> int intel_gvt_page_track_add(struct intel_vgpu *info, u64 gfn)
>> {
>> - struct kvm *kvm = info->kvm;
>> + struct kvm *kvm = info->vfio_device.kvm;
>> struct kvm_memory_slot *slot;
>> int idx;
>>
>> @@ -1743,7 +1697,7 @@ int intel_gvt_page_track_add(struct intel_vgpu *info, u64 gfn)
>>
>> int intel_gvt_page_track_remove(struct intel_vgpu *info, u64 gfn)
>> {
>> - struct kvm *kvm = info->kvm;
>> + struct kvm *kvm = info->vfio_device.kvm;
>> struct kvm_memory_slot *slot;
>> int idx;
>>
>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
>> index e8914024f5b1..a7d2a95796d3 100644
>> --- a/drivers/s390/crypto/vfio_ap_ops.c
>> +++ b/drivers/s390/crypto/vfio_ap_ops.c
>> @@ -1284,25 +1284,6 @@ static void vfio_ap_mdev_unset_kvm(struct ap_matrix_mdev *matrix_mdev)
>> }
>> }
>>
>> -static int vfio_ap_mdev_group_notifier(struct notifier_block *nb,
>> - unsigned long action, void *data)
>> -{
>> - int notify_rc = NOTIFY_OK;
>> - struct ap_matrix_mdev *matrix_mdev;
>> -
>> - if (action != VFIO_GROUP_NOTIFY_SET_KVM)
>> - return NOTIFY_OK;
>> -
>> - matrix_mdev = container_of(nb, struct ap_matrix_mdev, group_notifier);
>> -
>> - if (!data)
>> - vfio_ap_mdev_unset_kvm(matrix_mdev);
>> - else if (vfio_ap_mdev_set_kvm(matrix_mdev, data))
>> - notify_rc = NOTIFY_DONE;
>> -
>> - return notify_rc;
>> -}
>> -
>> static struct vfio_ap_queue *vfio_ap_find_queue(int apqn)
>> {
>> struct device *dev;
>> @@ -1402,11 +1383,10 @@ static int vfio_ap_mdev_open_device(struct vfio_device *vdev)
>> unsigned long events;
>> int ret;
>>
>> - matrix_mdev->group_notifier.notifier_call = vfio_ap_mdev_group_notifier;
>> - events = VFIO_GROUP_NOTIFY_SET_KVM;
>> + if (!vdev->kvm)
>> + return -EINVAL;
>>
>> - ret = vfio_register_notifier(vdev, VFIO_GROUP_NOTIFY, &events,
>> - &matrix_mdev->group_notifier);
>> + ret = vfio_ap_mdev_set_kvm(matrix_mdev, vdev->kvm);
>> if (ret)
>> return ret;
>>
>> @@ -1415,12 +1395,11 @@ static int vfio_ap_mdev_open_device(struct vfio_device *vdev)
>> ret = vfio_register_notifier(vdev, VFIO_IOMMU_NOTIFY, &events,
>> &matrix_mdev->iommu_notifier);
>> if (ret)
>> - goto out_unregister_group;
>> + goto err_kvm;
>> return 0;
>>
>> -out_unregister_group:
>> - vfio_unregister_notifier(vdev, VFIO_GROUP_NOTIFY,
>> - &matrix_mdev->group_notifier);
>> +err_kvm:
>> + vfio_ap_mdev_unset_kvm(matrix_mdev);
>> return ret;
>> }
>>
>> @@ -1431,8 +1410,6 @@ static void vfio_ap_mdev_close_device(struct vfio_device *vdev)
>>
>> vfio_unregister_notifier(vdev, VFIO_IOMMU_NOTIFY,
>> &matrix_mdev->iommu_notifier);
>> - vfio_unregister_notifier(vdev, VFIO_GROUP_NOTIFY,
>> - &matrix_mdev->group_notifier);
>> vfio_ap_mdev_unset_kvm(matrix_mdev);
>> }
>>
>> diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
>> index 648fcaf8104a..a26efd804d0d 100644
>> --- a/drivers/s390/crypto/vfio_ap_private.h
>> +++ b/drivers/s390/crypto/vfio_ap_private.h
>> @@ -81,8 +81,6 @@ struct ap_matrix {
>> * @node: allows the ap_matrix_mdev struct to be added to a list
>> * @matrix: the adapters, usage domains and control domains assigned to the
>> * mediated matrix device.
>> - * @group_notifier: notifier block used for specifying callback function for
>> - * handling the VFIO_GROUP_NOTIFY_SET_KVM event
>> * @iommu_notifier: notifier block used for specifying callback function for
>> * handling the VFIO_IOMMU_NOTIFY_DMA_UNMAP even
>> * @kvm: the struct holding guest's state
>> @@ -94,7 +92,6 @@ struct ap_matrix_mdev {
>> struct vfio_device vdev;
>> struct list_head node;
>> struct ap_matrix matrix;
>> - struct notifier_block group_notifier;
>> struct notifier_block iommu_notifier;
>> struct kvm *kvm;
>> crypto_hook pqap_hook;
>> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
>> index cfcff7764403..831fc722e3f8 100644
>> --- a/drivers/vfio/vfio.c
>> +++ b/drivers/vfio/vfio.c
>> @@ -1083,10 +1083,21 @@ static struct file *vfio_device_open(struct vfio_device *device)
>>
>> mutex_lock(&device->dev_set->lock);
>> device->open_count++;
>> - if (device->open_count == 1 && device->ops->open_device) {
>> - ret = device->ops->open_device(device);
>> - if (ret)
>> - goto err_undo_count;
>> + if (device->open_count == 1) {
>> + /*
>> + * Here we pass the KVM pointer with the group under the read
>> + * lock. If the device driver will use it, it must obtain a
>> + * reference and release it during close_device.
>> + */
>> + down_read(&device->group->group_rwsem);
>> + device->kvm = device->group->kvm;
>> +
>> + if (device->ops->open_device) {
>> + ret = device->ops->open_device(device);
>> + if (ret)
>> + goto err_undo_count;
>> + }
>> + up_read(&device->group->group_rwsem);
>> }
>> mutex_unlock(&device->dev_set->lock);
>>
>> @@ -1119,10 +1130,14 @@ static struct file *vfio_device_open(struct vfio_device *device)
>>
>> err_close_device:
>> mutex_lock(&device->dev_set->lock);
>> + down_read(&device->group->group_rwsem);
>> if (device->open_count == 1 && device->ops->close_device)
>> device->ops->close_device(device);
>> err_undo_count:
>> device->open_count--;
>> + if (device->open_count == 0 && device->kvm)
>> + device->kvm = NULL;
>> + up_read(&device->group->group_rwsem);
>> mutex_unlock(&device->dev_set->lock);
>> module_put(device->dev->driver->owner);
>> err_unassign_container:
>> @@ -1315,9 +1330,13 @@ static int vfio_device_fops_release(struct inode *inode, struct file *filep)
>>
>> mutex_lock(&device->dev_set->lock);
>> vfio_assert_device_open(device);
>> + down_read(&device->group->group_rwsem);
>> if (device->open_count == 1 && device->ops->close_device)
>> device->ops->close_device(device);
>> + up_read(&device->group->group_rwsem);
>> device->open_count--;
>> + if (device->open_count == 0)
>> + device->kvm = NULL;
>> mutex_unlock(&device->dev_set->lock);
>>
>> module_put(device->dev->driver->owner);
>> @@ -1726,8 +1745,8 @@ EXPORT_SYMBOL_GPL(vfio_file_enforced_coherent);
>> * @file: VFIO group file
>> * @kvm: KVM to link
>> *
>> - * The kvm pointer will be forwarded to all the vfio_device's attached to the
>> - * VFIO file via the VFIO_GROUP_NOTIFY_SET_KVM notifier.
>> + * When a VFIO device is first opened the KVM will be available in
>> + * device->kvm if one was associated with the group.
>> */
>> void vfio_file_set_kvm(struct file *file, struct kvm *kvm)
>> {
>> @@ -1738,8 +1757,6 @@ void vfio_file_set_kvm(struct file *file, struct kvm *kvm)
>>
>> down_write(&group->group_rwsem);
>> group->kvm = kvm;
>> - blocking_notifier_call_chain(&group->notifier,
>> - VFIO_GROUP_NOTIFY_SET_KVM, kvm);
>> up_write(&group->group_rwsem);
>> }
>> EXPORT_SYMBOL_GPL(vfio_file_set_kvm);
>> @@ -2006,7 +2023,8 @@ static int vfio_register_iommu_notifier(struct vfio_group *group,
>> struct vfio_iommu_driver *driver;
>> int ret;
>>
>> - down_read(&group->group_rwsem);
>> + lockdep_assert_held_read(&group->group_rwsem);
>> +
>> container = group->container;
>> driver = container->iommu_driver;
>> if (likely(driver && driver->ops->register_notifier))
>> @@ -2014,7 +2032,6 @@ static int vfio_register_iommu_notifier(struct vfio_group *group,
>> events, nb);
>> else
>> ret = -ENOTTY;
>> - up_read(&group->group_rwsem);
>>
>> return ret;
>> }
>> @@ -2026,7 +2043,8 @@ static int vfio_unregister_iommu_notifier(struct vfio_group *group,
>> struct vfio_iommu_driver *driver;
>> int ret;
>>
>> - down_read(&group->group_rwsem);
>> + lockdep_assert_held_read(&group->group_rwsem);
>> +
>> container = group->container;
>> driver = container->iommu_driver;
>> if (likely(driver && driver->ops->unregister_notifier))
>> @@ -2034,47 +2052,10 @@ static int vfio_unregister_iommu_notifier(struct vfio_group *group,
>> nb);
>> else
>> ret = -ENOTTY;
>> - up_read(&group->group_rwsem);
>>
>> return ret;
>> }
>>
>> -static int vfio_register_group_notifier(struct vfio_group *group,
>> - unsigned long *events,
>> - struct notifier_block *nb)
>> -{
>> - int ret;
>> - bool set_kvm = false;
>> -
>> - if (*events & VFIO_GROUP_NOTIFY_SET_KVM)
>> - set_kvm = true;
>> -
>> - /* clear known events */
>> - *events &= ~VFIO_GROUP_NOTIFY_SET_KVM;
>> -
>> - /* refuse to continue if still events remaining */
>> - if (*events)
>> - return -EINVAL;
>> -
>> - ret = blocking_notifier_chain_register(&group->notifier, nb);
>> - if (ret)
>> - return ret;
>> -
>> - /*
>> - * The attaching of kvm and vfio_group might already happen, so
>> - * here we replay once upon registration.
>> - */
>> - if (set_kvm) {
>> - down_read(&group->group_rwsem);
>> - if (group->kvm)
>> - blocking_notifier_call_chain(&group->notifier,
>> - VFIO_GROUP_NOTIFY_SET_KVM,
>> - group->kvm);
>> - up_read(&group->group_rwsem);
>> - }
>> - return 0;
>> -}
>> -
>> int vfio_register_notifier(struct vfio_device *device,
>> enum vfio_notify_type type, unsigned long *events,
>> struct notifier_block *nb)
>> @@ -2090,9 +2071,6 @@ int vfio_register_notifier(struct vfio_device *device,
>> case VFIO_IOMMU_NOTIFY:
>> ret = vfio_register_iommu_notifier(group, events, nb);
>> break;
>> - case VFIO_GROUP_NOTIFY:
>> - ret = vfio_register_group_notifier(group, events, nb);
>> - break;
>> default:
>> ret = -EINVAL;
>> }
>> @@ -2114,9 +2092,6 @@ int vfio_unregister_notifier(struct vfio_device *device,
>> case VFIO_IOMMU_NOTIFY:
>> ret = vfio_unregister_iommu_notifier(group, nb);
>> break;
>> - case VFIO_GROUP_NOTIFY:
>> - ret = blocking_notifier_chain_unregister(&group->notifier, nb);
>> - break;
>> default:
>> ret = -EINVAL;
>> }
>> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
>> index 45b287826ce6..aa888cc51757 100644
>> --- a/include/linux/vfio.h
>> +++ b/include/linux/vfio.h
>> @@ -36,6 +36,8 @@ struct vfio_device {
>> struct vfio_device_set *dev_set;
>> struct list_head dev_set_list;
>> unsigned int migration_flags;
>> + /* Driver must reference the kvm during open_device or never touch it */
>> + struct kvm *kvm;
>>
>> /* Members below here are private, not for driver use */
>> refcount_t refcount;
>> @@ -155,15 +157,11 @@ extern int vfio_dma_rw(struct vfio_device *device, dma_addr_t user_iova,
>> /* each type has independent events */
>> enum vfio_notify_type {
>> VFIO_IOMMU_NOTIFY = 0,
>> - VFIO_GROUP_NOTIFY = 1,
>> };
>>
>> /* events for VFIO_IOMMU_NOTIFY */
>> #define VFIO_IOMMU_NOTIFY_DMA_UNMAP BIT(0)
>>
>> -/* events for VFIO_GROUP_NOTIFY */
>> -#define VFIO_GROUP_NOTIFY_SET_KVM BIT(0)
>> -
>> extern int vfio_register_notifier(struct vfio_device *device,
>> enum vfio_notify_type type,
>> unsigned long *required_events,
>
Acked-by: Zhi Wang <zhi.a.wang@xxxxxxxxx>
