linux-kernel - Re: [PATCH v2] PCI: Do not attempt to set ExtTag for VFs

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Message-ID: <342E9A64-70B0-4BC6-B26E-4EA189C1BA6E@oracle.com>
Date: Wed, 7 Jan 2026 18:18:04 +0000
From: Haakon Bugge <haakon.bugge@...cle.com>
To: Bjorn Helgaas <bhelgaas@...gle.com>, Sinan Kaya <okaya@...eaurora.org>
CC: "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] PCI: Do not attempt to set ExtTag for VFs

>> 
>> 
>> On 12 Nov 2025, at 10:54, Håkon Bugge <Haakon.Bugge@...cle.com> wrote:
>> 
>> 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: 60db3a4d8cc9 ("PCI: Enable PCIe Extended Tags if supported")
>> Signed-off-by: Håkon Bugge <haakon.bugge@...cle.com>
> 
> A gentle ping on this one.

Once more.


Thxs, Håkon


> 
> 
> Thxs, Håkon
> 
> 
>> ---
>> 
>> v1 -> v2: Added ref to PCIe spec
>> ---
>> 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