[PATCH v7 10/10] hisi_acc_vfio_pci: Use its own PCI reset_done error handler

[Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>]

Register private handler for pci_error_handlers.reset_done and update
state accordingly.

Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
---
 .../vfio/pci/hisilicon/hisi_acc_vfio_pci.c    | 61 +++++++++++++++++--
 .../vfio/pci/hisilicon/hisi_acc_vfio_pci.h    |  4 +-
 2 files changed, 59 insertions(+), 6 deletions(-)

diff --git a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
index f733aa0b1a5b..906690e57020 100644
--- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
+++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
@@ -515,6 +515,27 @@ static void hisi_acc_vf_disable_fds(struct hisi_acc_vf_core_device *hisi_acc_vde
 	}
 }
 
+/*
+ * This function is called in all state_mutex unlock cases to
+ * handle a 'deferred_reset' if exists.
+ */
+static void
+hisi_acc_vf_state_mutex_unlock(struct hisi_acc_vf_core_device *hisi_acc_vdev)
+{
+again:
+	spin_lock(&hisi_acc_vdev->reset_lock);
+	if (hisi_acc_vdev->deferred_reset) {
+		hisi_acc_vdev->deferred_reset = false;
+		spin_unlock(&hisi_acc_vdev->reset_lock);
+		hisi_acc_vdev->vf_qm_state = QM_NOT_READY;
+		hisi_acc_vdev->mig_state = VFIO_DEVICE_STATE_RUNNING;
+		hisi_acc_vf_disable_fds(hisi_acc_vdev);
+		goto again;
+	}
+	mutex_unlock(&hisi_acc_vdev->state_mutex);
+	spin_unlock(&hisi_acc_vdev->reset_lock);
+}
+
 static int hisi_acc_vf_load_state(struct hisi_acc_vf_core_device *hisi_acc_vdev,
 				  struct hisi_acc_vf_migration_file *migf)
 {
@@ -750,7 +771,7 @@ static long hisi_acc_vf_save_unl_ioctl(struct file *filp,
 
 	mutex_lock(&hisi_acc_vdev->state_mutex);
 	if (hisi_acc_vdev->mig_state != VFIO_DEVICE_STATE_PRE_COPY) {
-		mutex_unlock(&hisi_acc_vdev->state_mutex);
+		hisi_acc_vf_state_mutex_unlock(hisi_acc_vdev);
 		return -EINVAL;
 	}
 
@@ -772,7 +793,7 @@ static long hisi_acc_vf_save_unl_ioctl(struct file *filp,
 	ret = copy_to_user((void __user *)arg, &info, minsz) ? -EFAULT : 0;
 out:
 	mutex_unlock(&migf->lock);
-	mutex_unlock(&hisi_acc_vdev->state_mutex);
+	hisi_acc_vf_state_mutex_unlock(hisi_acc_vdev);
 	return ret;
 }
 
@@ -967,7 +988,7 @@ hisi_acc_vfio_pci_set_device_state(struct vfio_device *vdev,
 			break;
 		}
 	}
-	mutex_unlock(&hisi_acc_vdev->state_mutex);
+	hisi_acc_vf_state_mutex_unlock(hisi_acc_vdev);
 	return res;
 }
 
@@ -980,10 +1001,35 @@ hisi_acc_vfio_pci_get_device_state(struct vfio_device *vdev,
 
 	mutex_lock(&hisi_acc_vdev->state_mutex);
 	*curr_state = hisi_acc_vdev->mig_state;
-	mutex_unlock(&hisi_acc_vdev->state_mutex);
+	hisi_acc_vf_state_mutex_unlock(hisi_acc_vdev);
 	return 0;
 }
 
+static void hisi_acc_vf_pci_aer_reset_done(struct pci_dev *pdev)
+{
+	struct hisi_acc_vf_core_device *hisi_acc_vdev = dev_get_drvdata(&pdev->dev);
+
+	if (hisi_acc_vdev->core_device.vdev.migration_flags !=
+				VFIO_MIGRATION_STOP_COPY)
+		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(&hisi_acc_vdev->reset_lock);
+	hisi_acc_vdev->deferred_reset = true;
+	if (!mutex_trylock(&hisi_acc_vdev->state_mutex)) {
+		spin_unlock(&hisi_acc_vdev->reset_lock);
+		return;
+	}
+	spin_unlock(&hisi_acc_vdev->reset_lock);
+	hisi_acc_vf_state_mutex_unlock(hisi_acc_vdev);
+}
+
 static int hisi_acc_vf_qm_init(struct hisi_acc_vf_core_device *hisi_acc_vdev)
 {
 	struct vfio_pci_core_device *vdev = &hisi_acc_vdev->core_device;
@@ -1302,12 +1348,17 @@ static const struct pci_device_id hisi_acc_vfio_pci_table[] = {
 
 MODULE_DEVICE_TABLE(pci, hisi_acc_vfio_pci_table);
 
+static const struct pci_error_handlers hisi_acc_vf_err_handlers = {
+	.reset_done = hisi_acc_vf_pci_aer_reset_done,
+	.error_detected = vfio_pci_core_aer_err_detected,
+};
+
 static struct pci_driver hisi_acc_vfio_pci_driver = {
 	.name = KBUILD_MODNAME,
 	.id_table = hisi_acc_vfio_pci_table,
 	.probe = hisi_acc_vfio_pci_probe,
 	.remove = hisi_acc_vfio_pci_remove,
-	.err_handler = &vfio_pci_core_err_handlers,
+	.err_handler = &hisi_acc_vf_err_handlers,
 };
 
 module_pci_driver(hisi_acc_vfio_pci_driver);
diff --git a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h
index 51bc7e92a776..6c18f7c74f34 100644
--- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h
+++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h
@@ -96,6 +96,7 @@ struct hisi_acc_vf_migration_file {
 struct hisi_acc_vf_core_device {
 	struct vfio_pci_core_device core_device;
 	u8 match_done:1;
+	u8 deferred_reset:1;
 	/* for migration state */
 	struct mutex state_mutex;
 	enum vfio_device_mig_state mig_state;
@@ -105,7 +106,8 @@ struct hisi_acc_vf_core_device {
 	struct hisi_qm vf_qm;
 	u32 vf_qm_state;
 	int vf_id;
-
+	/* for reset handler */
+	spinlock_t reset_lock;
 	struct hisi_acc_vf_migration_file resuming_migf;
 	struct hisi_acc_vf_migration_file saving_migf;
 };
-- 
2.25.1