PCI: Print more info in sriov_enable() error message

If we don't have space for all the bus numbers required to enable VFs,
print the largest bus number required and the range available.

No functional change; improved error message only.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Wei Yang <weiyang@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

drivers/pci/iov.c

@@ -180,6 +180,7 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
 	struct pci_dev *pdev;
 	struct pci_sriov *iov = dev->sriov;
 	int bars = 0;
+	u8 bus;
 
 	if (!nr_virtfn)
 		return 0;
@@ -216,8 +217,10 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
 	iov->offset = offset;
 	iov->stride = stride;
 
-	if (virtfn_bus(dev, nr_virtfn - 1) > dev->bus->busn_res.end) {
-		dev_err(&dev->dev, "SR-IOV: bus number out of range\n");
+	bus = virtfn_bus(dev, nr_virtfn - 1);
+	if (bus > dev->bus->busn_res.end) {
+		dev_err(&dev->dev, "can't enable %d VFs (bus %02x out of range of %pR)\n",
+			nr_virtfn, bus, &dev->bus->busn_res);
 		return -ENOMEM;
 	}