RE: [EXTERNAL] Re: [PATCH net-next] net: mana: Add handler for sriov configure

[Haiyang Zhang]

> -----Original Message-----
> From: Bjorn Helgaas <helgaas@xxxxxxxxxx>
> Sent: Wednesday, May 13, 2026 3:05 PM
> To: Leon Romanovsky <leon@xxxxxxxxxx>
> Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>; Haiyang Zhang
> <haiyangz@xxxxxxxxxxxxxxxxxxx>; Paul Rosswurm <paulros@xxxxxxxxxxxxx>;
> linux-hyperv@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; KY Srinivasan
> <kys@xxxxxxxxxxxxx>; Wei Liu <wei.liu@xxxxxxxxxx>; Dexuan Cui
> <DECUI@xxxxxxxxxxxxx>; Long Li <longli@xxxxxxxxxxxxx>; Andrew Lunn
> <andrew+netdev@xxxxxxx>; David S. Miller <davem@xxxxxxxxxxxxx>; Eric
> Dumazet <edumazet@xxxxxxxxxx>; Jakub Kicinski <kuba@xxxxxxxxxx>; Paolo
> Abeni <pabeni@xxxxxxxxxx>; Bjorn Helgaas <bhelgaas@xxxxxxxxxx>; Simon
> Horman <horms@xxxxxxxxxx>; Shradha Gupta
> <shradhagupta@xxxxxxxxxxxxxxxxxxx>; Dipayaan Roy
> <dipayanroy@xxxxxxxxxxxxxxxxxxx>; Erni Sri Satya Vennela
> <ernis@xxxxxxxxxxxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx; linux-
> pci@xxxxxxxxxxxxxxx
> Subject: Re: [EXTERNAL] Re: [PATCH net-next] net: mana: Add handler for
> sriov configure
> 
> On Wed, May 13, 2026 at 09:47:49PM +0300, Leon Romanovsky wrote:
> > On Fri, May 08, 2026 at 06:10:29PM -0500, Bjorn Helgaas wrote:
> > > On Fri, May 08, 2026 at 10:47:14PM +0000, Haiyang Zhang wrote:
> > > > > On Fri, May 08, 2026 at 03:04:06PM -0700, Haiyang Zhang wrote:
> > > > > > From: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> > > > > >
> > > > > > Add callback function for the pci_driver, sriov_configure.
> > > > > >
> > > > > > Also disable VF autoprobe when it runs as PF driver on bare
> metal,
> > > > > > since the hardware side may not have the VF ready immediately.
> > > > > >
> > > > > > Export pci_vf_drivers_autoprobe() so the driver can toggle the
> VF
> > > > > > autoprobe flag.
> > > > >
> > > > > Technically pci_vf_drivers_autoprobe() doesn't *toggle* the
> autoprobe
> > > > > flag.  That would mean setting it to the opposite of its current
> > > > > value.
> > > > >
> > > > > Here I would say "so the driver can prevent autoprobing of the
> VFs",
> > > > > which is the intent.
> > > > Thanks, I will change the wording.
> > > >
> > > > >
> > > > > Out of curiosity, how do the VFs eventually get probed?  I guess
> > > > > there's some other mechanism that tells you when they're ready,
> and
> > > > > you manually use sysfs 'sriov_drivers_autoprobe' to enable
> probing,
> > > > > then bind drivers to them via sysfs?
> > > > We have a user program talking to the Azure backplane to get that
> information.
> > > > @Paul Rosswurm, do you have more details?
> > > >
> > > >
> > > > > The prevention of autoprobing sounds like a critical part of this
> > > > > change; might be worth saying something in the subject, because
> "add
> > > > > sriov configure" doesn't include much information.
> > > > How about "Add handler for sriov configure with VF autoprobe off"?
> > >
> > > OK by me :)
> >
> > I believe it is the wrong decision to allow toggling a user‑visible knob
> > without the user’s awareness. In this case, they can either disable
> > autoprobe on the PF or rely on EPROBE_DEFER. In all cases, the same
> > functionality can be achieved without changing PCI autoprobe code.
> 
> OK, Haiyang, can you drop my ack please?  If Leon's solutions don't
> work for you, continue this conversation and we can explore
> alternatives.

Sure, I will submit an updated patch without changing VF autoprobe.

Thanks,
- Haiyang