genirq/msi: Use PCI device property

to determine whether this is MSI or MSIX instead of consulting MSI
descriptors.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20211210221813.434156196@linutronix.de

kernel/irq/msi.c

@@ -77,21 +77,8 @@ EXPORT_SYMBOL_GPL(get_cached_msi_msg);
 static ssize_t msi_mode_show(struct device *dev, struct device_attribute *attr,
 			     char *buf)
 {
-	struct msi_desc *entry;
-	bool is_msix = false;
-	unsigned long irq;
-	int retval;
-
-	retval = kstrtoul(attr->attr.name, 10, &irq);
-	if (retval)
-		return retval;
-
-	entry = irq_get_msi_desc(irq);
-	if (!entry)
-		return -ENODEV;
-
-	if (dev_is_pci(dev))
-		is_msix = entry->pci.msi_attrib.is_msix;
+	/* MSI vs. MSIX is per device not per interrupt */
+	bool is_msix = dev_is_pci(dev) ? to_pci_dev(dev)->msix_enabled : false;
 
 	return sysfs_emit(buf, "%s\n", is_msix ? "msix" : "msi");
 }