Resetting the migration device state is typically delegated to PCI .reset_done() callback. With VFIO, reset is usually called under vdev->memory_lock, which causes lockdep to report a following circular locking dependency scenario:
0: set_device_state driver->state_mutex -> migf->lock 1: data_read migf->lock -> mm->mmap_lock 2: vfio_pin_dma mm->mmap_lock -> vdev->memory_lock 3: vfio_pci_ioctl_reset vdev->memory_lock -> driver->state_mutex Introduce a .migration_reset_state() callback called outside of vdev->memory_lock to break the dependency chain. Signed-off-by: Michał Winiarski <[email protected]> --- drivers/vfio/pci/vfio_pci_core.c | 25 ++++++++++++++++++++++--- include/linux/vfio.h | 4 ++++ 2 files changed, 26 insertions(+), 3 deletions(-) diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c index 7dcf5439dedc9..d919636558ec8 100644 --- a/drivers/vfio/pci/vfio_pci_core.c +++ b/drivers/vfio/pci/vfio_pci_core.c @@ -553,6 +553,16 @@ int vfio_pci_core_enable(struct vfio_pci_core_device *vdev) } EXPORT_SYMBOL_GPL(vfio_pci_core_enable); +static void vfio_pci_dev_migration_reset_state(struct vfio_pci_core_device *vdev) +{ + lockdep_assert_not_held(&vdev->memory_lock); + + if (!vdev->vdev.mig_ops->migration_reset_state) + return; + + vdev->vdev.mig_ops->migration_reset_state(&vdev->vdev); +} + void vfio_pci_core_disable(struct vfio_pci_core_device *vdev) { struct pci_dev *pdev = vdev->pdev; @@ -662,8 +672,10 @@ void vfio_pci_core_disable(struct vfio_pci_core_device *vdev) * overwrite the previously restored configuration information. */ if (vdev->reset_works && pci_dev_trylock(pdev)) { - if (!__pci_reset_function_locked(pdev)) + if (!__pci_reset_function_locked(pdev)) { vdev->needs_reset = false; + vfio_pci_dev_migration_reset_state(vdev); + } pci_dev_unlock(pdev); } @@ -1230,6 +1242,8 @@ static int vfio_pci_ioctl_reset(struct vfio_pci_core_device *vdev, ret = pci_try_reset_function(vdev->pdev); up_write(&vdev->memory_lock); + vfio_pci_dev_migration_reset_state(vdev); + return ret; } @@ -2129,6 +2143,7 @@ int vfio_pci_core_register_device(struct vfio_pci_core_device *vdev) if (vdev->vdev.mig_ops) { if (!(vdev->vdev.mig_ops->migration_get_state && vdev->vdev.mig_ops->migration_set_state && + vdev->vdev.mig_ops->migration_reset_state && vdev->vdev.mig_ops->migration_get_data_size) || !(vdev->vdev.migration_flags & VFIO_MIGRATION_STOP_COPY)) return -EINVAL; @@ -2486,8 +2501,10 @@ static int vfio_pci_dev_set_hot_reset(struct vfio_device_set *dev_set, err_undo: list_for_each_entry_from_reverse(vdev, &dev_set->device_list, - vdev.dev_set_list) + vdev.dev_set_list) { up_write(&vdev->memory_lock); + vfio_pci_dev_migration_reset_state(vdev); + } list_for_each_entry(vdev, &dev_set->device_list, vdev.dev_set_list) pm_runtime_put(&vdev->pdev->dev); @@ -2543,8 +2560,10 @@ static void vfio_pci_dev_set_try_reset(struct vfio_device_set *dev_set) reset_done = true; list_for_each_entry(cur, &dev_set->device_list, vdev.dev_set_list) { - if (reset_done) + if (reset_done) { cur->needs_reset = false; + vfio_pci_dev_migration_reset_state(cur); + } if (!disable_idle_d3) pm_runtime_put(&cur->pdev->dev); diff --git a/include/linux/vfio.h b/include/linux/vfio.h index eb563f538dee5..36aab2df40700 100644 --- a/include/linux/vfio.h +++ b/include/linux/vfio.h @@ -213,6 +213,9 @@ static inline bool vfio_device_cdev_opened(struct vfio_device *device) * @migration_get_state: Optional callback to get the migration state for * devices that support migration. It's mandatory for * VFIO_DEVICE_FEATURE_MIGRATION migration support. + * @migration_reset_state: Optional callback to reset the migration state for + * devices that support migration. It's mandatory for + * VFIO_DEVICE_FEATURE_MIGRATION migration support. * @migration_get_data_size: Optional callback to get the estimated data * length that will be required to complete stop copy. It's mandatory for * VFIO_DEVICE_FEATURE_MIGRATION migration support. @@ -223,6 +226,7 @@ struct vfio_migration_ops { enum vfio_device_mig_state new_state); int (*migration_get_state)(struct vfio_device *device, enum vfio_device_mig_state *curr_state); + void (*migration_reset_state)(struct vfio_device *device); int (*migration_get_data_size)(struct vfio_device *device, unsigned long *stop_copy_length); }; -- 2.51.2
