1 files changed, 25 insertions, 6 deletions

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 70f10fa..fe5b50b 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -170,7 +170,7 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
 {
 	u32 l, sz, mask;
 	u16 orig_cmd;
-	struct pci_bus_region region;
+	struct pci_bus_region region, inverted_region;
 	bool bar_too_big = false, bar_disabled = false;
 
 	mask = type ? PCI_ROM_ADDRESS_MASK : ~0;
@@ -250,12 +250,10 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
 			pci_write_config_dword(dev, pos + 4, 0);
 			region.start = 0;
 			region.end = sz64;
-			pcibios_bus_to_resource(dev, res, &region);
 			bar_disabled = true;
 		} else {
 			region.start = l64;
 			region.end = l64 + sz64;
-			pcibios_bus_to_resource(dev, res, &region);
 		}
 	} else {
 		sz = pci_size(l, sz, mask);
@@ -265,7 +263,28 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
 
 		region.start = l;
 		region.end = l + sz;
-		pcibios_bus_to_resource(dev, res, &region);
+	}
+
+	pcibios_bus_to_resource(dev, res, &region);
+	pcibios_resource_to_bus(dev, &inverted_region, res);
+
+	/*
+	 * If "A" is a BAR value (a bus address), "bus_to_resource(A)" is
+	 * the corresponding resource address (the physical address used by
+	 * the CPU.  Converting that resource address back to a bus address
+	 * should yield the original BAR value:
+	 *
+	 *     resource_to_bus(bus_to_resource(A)) == A
+	 *
+	 * If it doesn't, CPU accesses to "bus_to_resource(A)" will not
+	 * be claimed by the device.
+	 */
+	if (inverted_region.start != region.start) {
+		dev_info(&dev->dev, "reg 0x%x: initial BAR value %pa invalid; forcing reassignment\n",
+			 pos, &region.start);
+		res->flags |= IORESOURCE_UNSET;
+		res->end -= res->start;
+		res->start = 0;
 	}
 
 	goto out;
@@ -278,9 +297,9 @@ out:
 		pci_write_config_word(dev, PCI_COMMAND, orig_cmd);
 
 	if (bar_too_big)
-		dev_err(&dev->dev, "reg %x: can't handle 64-bit BAR\n", pos);
+		dev_err(&dev->dev, "reg 0x%x: can't handle 64-bit BAR\n", pos);
 	if (res->flags && !bar_disabled)
-		dev_printk(KERN_DEBUG, &dev->dev, "reg %x: %pR\n", pos, res);
+		dev_printk(KERN_DEBUG, &dev->dev, "reg 0x%x: %pR\n", pos, res);
 
 	return (res->flags & IORESOURCE_MEM_64) ? 1 : 0;
 }