[v1] PCI: Do not attempt to set ExtTag for VFs

[PATCH] PCI: Do not attempt to set ExtTag for VFs

Posted by Håkon Bugge 2 months, 3 weeks ago

The bit for enabling extended tags is Reserved and Preserved (RsvdP)
for VFs. 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: 60db3a4d8cc9 ("PCI: Enable PCIe Extended Tags if supported")
Signed-off-by: Håkon Bugge <haakon.bugge@oracle.com>
---
 drivers/pci/probe.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 0ce98e18b5a87..014017e15bcc8 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2244,7 +2244,8 @@ 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);
-- 
2.43.5

Re: [PATCH] PCI: Do not attempt to set ExtTag for VFs

Posted by Ilpo Järvinen 2 months, 3 weeks ago

On Tue, 11 Nov 2025, Håkon Bugge wrote:

> The bit for enabling extended tags is Reserved and Preserved (RsvdP)
> for VFs.

Please add a PCIe spec reference.

> 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: 60db3a4d8cc9 ("PCI: Enable PCIe Extended Tags if supported")
> Signed-off-by: Håkon Bugge <haakon.bugge@oracle.com>
> ---
>  drivers/pci/probe.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 0ce98e18b5a87..014017e15bcc8 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -2244,7 +2244,8 @@ 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);
> 

-- 
 i.