[PATCH v3 1/3] hisi_acc_vfio_pci: fix live migration enable conditions for PF passthrough

[Longfang Liu <liulongfang@huawei.com>]

When a PF device is bound to the live migration driver in passthrough mode,
it cannot support live migration functionality, and key pointers will
remain uninitialized. Although most migration functions within the driver
are unreachable, low-level error handling callbacks may be triggered
directly, causing a crash due to null pointer dereference.
The fix involves adding validity checks at three entry points: device
probe, error handling, and migration initialization. If the pointer is
invalid, the operation is exited or rejected directly to avoid crashes,
while redundant internal checks are removed.

Fixes: b0eed085903e ("hisi_acc_vfio_pci: Add support for VFIO live migration")
Signed-off-by: Longfang Liu <liulongfang@huawei.com>
---
 .../vfio/pci/hisilicon/hisi_acc_vfio_pci.c    | 24 ++++++++++++++-----
 1 file changed, 18 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 86362ec424a5..e95d0ab0f11a 100644
--- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
+++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
@@ -1154,9 +1154,14 @@ static void hisi_acc_vf_pci_reset_prepare(struct pci_dev *pdev)
 {
 	struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_drvdata(pdev);
 	struct hisi_qm *qm = hisi_acc_vdev->pf_qm;
-	struct device *dev = &qm->pdev->dev;
+	struct device *dev = &pdev->dev;
 	u32 delay = 0;
 
+	if (!qm || !qm->io_base) {
+		dev_err(dev, "PF QM not available for reset\n");
+		return;
+	}
+
 	/* All reset requests need to be queued for processing */
 	while (test_and_set_bit(QM_RESETTING, &qm->misc_ctl)) {
 		msleep(1);
@@ -1174,8 +1179,12 @@ static void hisi_acc_vf_pci_aer_reset_done(struct pci_dev *pdev)
 	struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_drvdata(pdev);
 	struct hisi_qm *qm = hisi_acc_vdev->pf_qm;
 
-	if (hisi_acc_vdev->set_reset_flag)
-		clear_bit(QM_RESETTING, &qm->misc_ctl);
+	if (hisi_acc_vdev->set_reset_flag) {
+		if (qm && qm->io_base)
+			clear_bit(QM_RESETTING, &qm->misc_ctl);
+		else
+			dev_err(&pdev->dev, "PF QM not available for reset done\n");
+	}
 
 	if (!hisi_acc_vdev->core_device.vdev.mig_ops)
 		return;
@@ -1565,6 +1574,11 @@ static int hisi_acc_vfio_pci_migrn_init_dev(struct vfio_device *core_vdev)
 	struct pci_dev *pdev = to_pci_dev(core_vdev->dev);
 	struct hisi_qm *pf_qm = hisi_acc_get_pf_qm(pdev);
 
+	if (!pf_qm) {
+		dev_err(&pdev->dev, "PF driver not loaded, cannot enable migration\n");
+		return -ENODEV;
+	}
+
 	hisi_acc_vdev->vf_id = pci_iov_vf_id(pdev) + 1;
 	hisi_acc_vdev->pf_qm = pf_qm;
 	hisi_acc_vdev->vf_dev = pdev;
@@ -1670,13 +1684,11 @@ static int hisi_acc_vfio_pci_probe(struct pci_dev *pdev, const struct pci_device
 	struct hisi_acc_vf_core_device *hisi_acc_vdev;
 	const struct vfio_device_ops *ops = &hisi_acc_vfio_pci_ops;
 	struct hisi_qm *pf_qm;
-	int vf_id;
 	int ret;
 
 	pf_qm = hisi_acc_get_pf_qm(pdev);
 	if (pf_qm && pf_qm->ver >= QM_HW_V3) {
-		vf_id = pci_iov_vf_id(pdev);
-		if (vf_id >= 0)
+		if (pdev->is_virtfn)
 			ops = &hisi_acc_vfio_pci_migrn_ops;
 		else
 			pci_warn(pdev, "migration support failed, continue with generic interface\n");
-- 
2.43.0