1 files changed, 18 insertions, 11 deletions

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index b4a90badd0a6..44f15ff70c1d 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -103,6 +103,16 @@ static void msix_set_enable(struct pci_dev *dev, int enable)
 	}
 }
 
+/*
+ * Essentially, this is ((1 << (1 << x)) - 1), but without the
+ * undefinedness of a << 32.
+ */
+static inline __attribute_const__ u32 msi_mask(unsigned x)
+{
+	static const u32 mask[] = { 1, 2, 4, 0xf, 0xff, 0xffff, 0xffffffff };
+	return mask[x];
+}
+
 static void msix_flush_writes(struct irq_desc *desc)
 {
 	struct msi_desc *entry;
@@ -398,21 +408,18 @@ static int msi_capability_init(struct pci_dev *dev)
 	entry->msi_attrib.masked = 1;
 	entry->msi_attrib.default_irq = dev->irq;	/* Save IOAPIC IRQ */
 	entry->msi_attrib.pos = pos;
-	if (entry->msi_attrib.maskbit) {
-		entry->mask_base = (void __iomem *)(long)msi_mask_bits_reg(pos,
-				entry->msi_attrib.is_64);
-	}
 	entry->dev = dev;
 	if (entry->msi_attrib.maskbit) {
-		unsigned int maskbits, temp;
+		unsigned int base, maskbits, temp;
+
+		base = msi_mask_bits_reg(pos, entry->msi_attrib.is_64);
+		entry->mask_base = (void __iomem *)(long)base;
+
 		/* All MSIs are unmasked by default, Mask them all */
-		pci_read_config_dword(dev,
-			msi_mask_bits_reg(pos, entry->msi_attrib.is_64),
-			&maskbits);
-		temp = (1 << multi_msi_capable(control));
-		temp = ((temp - 1) & ~temp);
+		pci_read_config_dword(dev, base, &maskbits);
+		temp = msi_mask((control & PCI_MSI_FLAGS_QMASK) >> 1);
 		maskbits |= temp;
-		pci_write_config_dword(dev, entry->msi_attrib.is_64, maskbits);
+		pci_write_config_dword(dev, base, maskbits);
 		entry->msi_attrib.maskbits_mask = temp;
 	}
 	list_add_tail(&entry->list, &dev->msi_list);