PCI/IOV: Skip BAR sizing for VFs

Per PCIe r4.0, sec 9.3.4.1.11, the BAR registers in VF config space are all
RO Zero, so skip sizing them.

This is an optimization when enabling SR-IOV on a device with many VFs.
Suggested-by: NBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: NKarimAllah Ahmed <karahmed@amazon.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

drivers/pci/probe.c

@@ -329,6 +329,10 @@ static void pci_read_bases(struct pci_dev *dev, unsigned int howmany, int rom)
 	if (dev->non_compliant_bars)
 		return;
 
+	/* Per PCIe r4.0, sec 9.3.4.1.11, the VF BARs are all RO Zero */
+	if (dev->is_virtfn)
+		return;
+
 	for (pos = 0; pos < howmany; pos++) {
 		struct resource *res = &dev->resource[pos];
 		reg = PCI_BASE_ADDRESS_0 + (pos << 2);