+ if (dev->msix_enabled)
+ return -EALREADY;
+
+ /*
+ * PCI_COMMAND_MEMORY must be enabled, otherwise we may not be able
+ * to access the BARs where the MSI-X entries reside.
+ * But VF devices are unique in which the PF needs to be checked.
+ */
+ pci_read_config_word(pci_physfn(dev), PCI_COMMAND, &cmd);
+ if (dev->msi_enabled || !(cmd & PCI_COMMAND_MEMORY))
+ return -ENXIO;
+