PCI/MSI: Sanitize MSI-X table map handling

Unmapping the MSI-X base mapping in the loops which allocate/free MSI
descriptors is daft and in the way of allowing runtime expansion of MSI-X
descriptors.

Store the mapping in struct pci_dev and free it after freeing the MSI-X
descriptors.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/20211206210224.871651518@linutronix.de

drivers/pci/msi/msi.c

@@ -241,14 +241,14 @@ static void free_msi_irqs(struct pci_dev *dev)
 	pci_msi_teardown_msi_irqs(dev);
 
 	list_for_each_entry_safe(entry, tmp, msi_list, list) {
-		if (entry->pci.msi_attrib.is_msix) {
-			if (list_is_last(&entry->list, msi_list))
-				iounmap(entry->pci.mask_base);
-		}
-
 		list_del(&entry->list);
 		free_msi_entry(entry);
 	}
+
+	if (dev->msix_base) {
+		iounmap(dev->msix_base);
+		dev->msix_base = NULL;
+	}
 }
 
 static void pci_intx_for_msi(struct pci_dev *dev, int enable)
@@ -501,10 +501,6 @@ static int msix_setup_entries(struct pci_dev *dev, void __iomem *base,
 	for (i = 0, curmsk = masks; i < nvec; i++) {
 		entry = alloc_msi_entry(&dev->dev, 1, curmsk);
 		if (!entry) {
-			if (!i)
-				iounmap(base);
-			else
-				free_msi_irqs(dev);
 			/* No enough memory. Don't try again */
 			ret = -ENOMEM;
 			goto out;
@@ -602,12 +598,14 @@ static int msix_capability_init(struct pci_dev *dev, struct msix_entry *entries,
 		goto out_disable;
 	}
 
+	dev->msix_base = base;
+
 	/* Ensure that all table entries are masked. */
 	msix_mask_all(base, tsize);
 
 	ret = msix_setup_entries(dev, base, entries, nvec, affd);
 	if (ret)
-		goto out_disable;
+		goto out_free;
 
 	ret = pci_msi_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSIX);
 	if (ret)

include/linux/pci.h

@@ -473,6 +473,7 @@ struct pci_dev {
 	u8		ptm_granularity;
 #endif
 #ifdef CONFIG_PCI_MSI
+	void __iomem	*msix_base;
 	const struct attribute_group **msi_irq_groups;
 #endif
 	struct pci_vpd	vpd;