Re: [PATCH 1/3] PCI: endpoint: pci-epf-vntb: Pass PF/VF number when BAR programming

[Koichiro Den]

On Tue, Sep 08, 2026 at 11:53:15AM -0500, Bjorn Helgaas wrote:
> On Wed, Jul 29, 2026 at 02:23:04AM +0900, Koichiro Den wrote:
> > vntb_epf_mw_set_trans() programs the memory-window BAR through
> > pci_epc_set_bar() with hardcoded function numbers (0, 0), so the BAR
> > lands on the wrong function whenever the vNTB EPF is bound to anything
> > but PF0. The other BAR programming sites in the vNTB driver already pass
> > the EPF's own numbers.
> > 
> > Pass the EPF's own func_no/vfunc_no here as well.
> 
> We're referring to these as "PF" and "VF" in the subject and "physical
> endpoint function" and "virtual endpoint function" in the
> pci_epc_set_bar() kernel-doc, but I don't think these have anything to
> do with the SR-IOV PF and VF concepts, do they?

Not in the specific case that motivated this series. But AFAICT, the EPC API
uses the same (func_no, vfunc_no) pair to cover both ordinary functions and
SR-IOV PFs/VFs scenarios. With vfunc_no == 0, func_no can identify either an
ordinary function or an SR-IOV PF. A non-zero vfunc_no identifies a VF
associated with the PF selected by func_no.

> 
> I don't have a better naming suggestion, but this is slightly
> confusing.

Perhaps a better subject might be:

  PCI: endpoint: pci-epf-vntb: Pass (func_no, vfunc_no) when programming BARs

Best regards,
Koichiro

> 
> > Fixes: e35f56bb0330 ("PCI: endpoint: Support NTB transfer between RC and EP")
> > Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>
> > ---
> >  drivers/pci/endpoint/functions/pci-epf-vntb.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> > index c3caec927d74..fba65abfb6b2 100644
> > --- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
> > +++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> > @@ -1427,7 +1427,8 @@ static int vntb_epf_mw_set_trans(struct ntb_dev *ndev, int pidx, int idx,
> >  	epf_bar->barno = barno;
> >  	epf_bar->size = size;
> >  
> > -	ret = pci_epc_set_bar(ntb->epf->epc, 0, 0, epf_bar);
> > +	ret = pci_epc_set_bar(ntb->epf->epc, ntb->epf->func_no,
> > +			      ntb->epf->vfunc_no, epf_bar);
> >  	if (ret) {
> >  		dev_err(dev, "failure set mw trans\n");
> >  		return ret;
> > -- 
> > 2.51.0
> >