PCI: hv: Fix a crash in hv_pci_restore_msi_msg() during hibernation

When a Linux VM with an assigned PCI device runs on Hyper-V, if the PCI
device driver is not loaded yet (i.e. MSI-X/MSI is not enabled on the
device yet), doing a VM hibernation triggers a panic in
hv_pci_restore_msi_msg() -> msi_lock_descs(&pdev->dev), because
pdev->dev.msi.data is still NULL.

Avoid the panic by checking if MSI-X/MSI is enabled.

Link: https://lore.kernel.org/r/20230816175939.21566-1-decui@microsoft.com
Fixes: dc2b453 ("PCI: hv: Rework MSI handling")
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: sathyanarayanan.kuppuswamy@linux.intel.com
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Cc: stable@vger.kernel.org

Author: dcui

drivers/pci/controller/pci-hyperv.c

@@ -3983,6 +3983,9 @@ static int hv_pci_restore_msi_msg(struct pci_dev *pdev, void *arg)
 	struct msi_desc *entry;
 	int ret = 0;
 
+	if (!pdev->msi_enabled && !pdev->msix_enabled)
+		return 0;
+
 	msi_lock_descs(&pdev->dev);
 	msi_for_each_desc(entry, &pdev->dev, MSI_DESC_ASSOCIATED) {
 		irq_data = irq_get_irq_data(entry->irq);