vfio/mlx5: Use its own PCI reset_done error handler

Register its own handler for pci_error_handlers.reset_done and update
state accordingly.

Link: https://lore.kernel.org/all/20220224142024.147653-16-yishaih@nvidia.com
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>

diff --git a/drivers/vfio/pci/mlx5/main.c b/drivers/vfio/pci/mlx5/main.c
index ae1e40f..282a9d4 100644 (file)
--- a/drivers/vfio/pci/mlx5/main.c
+++ b/drivers/vfio/pci/mlx5/main.c
@@ -29,9 +29,12 @@ struct mlx5vf_pci_core_device {
        struct vfio_pci_core_device core_device;
        u16 vhca_id;
        u8 migrate_cap:1;
+       u8 deferred_reset:1;
        /* protect migration state */
        struct mutex state_mutex;
        enum vfio_device_mig_state mig_state;
+       /* protect the reset_done flow */
+       spinlock_t reset_lock;
        struct mlx5_vf_migration_file *resuming_migf;
        struct mlx5_vf_migration_file *saving_migf;
 };
@@ -437,6 +440,25 @@ mlx5vf_pci_step_device_state_locked(struct mlx5vf_pci_core_device *mvdev,
        return ERR_PTR(-EINVAL);
 }
 
+/*
+ * This function is called in all state_mutex unlock cases to
+ * handle a 'deferred_reset' if exists.
+ */
+static void mlx5vf_state_mutex_unlock(struct mlx5vf_pci_core_device *mvdev)
+{
+again:
+       spin_lock(&mvdev->reset_lock);
+       if (mvdev->deferred_reset) {
+               mvdev->deferred_reset = false;
+               spin_unlock(&mvdev->reset_lock);
+               mvdev->mig_state = VFIO_DEVICE_STATE_RUNNING;
+               mlx5vf_disable_fds(mvdev);
+               goto again;
+       }
+       mutex_unlock(&mvdev->state_mutex);
+       spin_unlock(&mvdev->reset_lock);
+}
+
 static struct file *
 mlx5vf_pci_set_device_state(struct vfio_device *vdev,
                            enum vfio_device_mig_state new_state)
@@ -465,7 +487,7 @@ mlx5vf_pci_set_device_state(struct vfio_device *vdev,
                        break;
                }
        }
-       mutex_unlock(&mvdev->state_mutex);
+       mlx5vf_state_mutex_unlock(mvdev);
        return res;
 }
 
@@ -477,10 +499,34 @@ static int mlx5vf_pci_get_device_state(struct vfio_device *vdev,
 
        mutex_lock(&mvdev->state_mutex);
        *curr_state = mvdev->mig_state;
-       mutex_unlock(&mvdev->state_mutex);
+       mlx5vf_state_mutex_unlock(mvdev);
        return 0;
 }
 
+static void mlx5vf_pci_aer_reset_done(struct pci_dev *pdev)
+{
+       struct mlx5vf_pci_core_device *mvdev = dev_get_drvdata(&pdev->dev);
+
+       if (!mvdev->migrate_cap)
+               return;
+
+       /*
+        * As the higher VFIO layers are holding locks across reset and using
+        * those same locks with the mm_lock we need to prevent ABBA deadlock
+        * with the state_mutex and mm_lock.
+        * In case the state_mutex was taken already we defer the cleanup work
+        * to the unlock flow of the other running context.
+        */
+       spin_lock(&mvdev->reset_lock);
+       mvdev->deferred_reset = true;
+       if (!mutex_trylock(&mvdev->state_mutex)) {
+               spin_unlock(&mvdev->reset_lock);
+               return;
+       }
+       spin_unlock(&mvdev->reset_lock);
+       mlx5vf_state_mutex_unlock(mvdev);
+}
+
 static int mlx5vf_pci_open_device(struct vfio_device *core_vdev)
 {
        struct mlx5vf_pci_core_device *mvdev = container_of(
@@ -562,6 +608,7 @@ static int mlx5vf_pci_probe(struct pci_dev *pdev,
                                        VFIO_MIGRATION_STOP_COPY |
                                        VFIO_MIGRATION_P2P;
                                mutex_init(&mvdev->state_mutex);
+                               spin_lock_init(&mvdev->reset_lock);
                        }
                        mlx5_vf_put_core_dev(mdev);
                }
@@ -596,11 +643,17 @@ static const struct pci_device_id mlx5vf_pci_table[] = {
 
 MODULE_DEVICE_TABLE(pci, mlx5vf_pci_table);
 
+static const struct pci_error_handlers mlx5vf_err_handlers = {
+       .reset_done = mlx5vf_pci_aer_reset_done,
+       .error_detected = vfio_pci_core_aer_err_detected,
+};
+
 static struct pci_driver mlx5vf_pci_driver = {
        .name = KBUILD_MODNAME,
        .id_table = mlx5vf_pci_table,
        .probe = mlx5vf_pci_probe,
        .remove = mlx5vf_pci_remove,
+       .err_handler = &mlx5vf_err_handlers,
 };
 
 static void __exit mlx5vf_pci_cleanup(void)