PCI: Do not attempt to set ExtTag for VFs

[ Upstream commit 7371173 ]

The bit for enabling extended tags is Reserved and Preserved (RsvdP) for
VFs, according to PCIe r7.0 section 7.5.3.4 table 7.21.  Hence, bail out
early from pci_configure_extended_tags() if the device is a VF.

Otherwise, we may see incorrect log messages such as:

  kernel: pci 0000:af:00.2: enabling Extended Tags

(af:00.2 is a VF)

Fixes: 60db3a4 ("PCI: Enable PCIe Extended Tags if supported")
Signed-off-by: Håkon Bugge <haakon.bugge@oracle.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Link: https://patch.msgid.link/20251112095442.1913258-1-haakon.bugge@oracle.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: Hakon-Bugge

drivers/pci/probe.c

@@ -2101,7 +2101,8 @@ int pci_configure_extended_tags(struct pci_dev *dev, void *ign)
 	u16 ctl;
 	int ret;
 
-	if (!pci_is_pcie(dev))
+	/* PCI_EXP_DEVCTL_EXT_TAG is RsvdP in VFs */
+	if (!pci_is_pcie(dev) || dev->is_virtfn)
 		return 0;
 
 	ret = pcie_capability_read_dword(dev, PCI_EXP_DEVCAP, &cap);