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

[Leon Romanovsky <leon@kernel.org>]

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:
> > > -----Original Message-----
> > > From: Bjorn Helgaas <helgaas@kernel.org>
> > > Sent: Friday, May 8, 2026 6:38 PM
> > > To: Haiyang Zhang <haiyangz@linux.microsoft.com>
> > > Cc: linux-hyperv@vger.kernel.org; netdev@vger.kernel.org; KY Srinivasan
> > > <kys@microsoft.com>; Haiyang Zhang <haiyangz@microsoft.com>; Wei Liu
> > > <wei.liu@kernel.org>; Dexuan Cui <DECUI@microsoft.com>; Long Li
> > > <longli@microsoft.com>; Andrew Lunn <andrew+netdev@lunn.ch>; David S.
> > > Miller <davem@davemloft.net>; Eric Dumazet <edumazet@google.com>; Jakub
> > > Kicinski <kuba@kernel.org>; Paolo Abeni <pabeni@redhat.com>; Bjorn Helgaas
> > > <bhelgaas@google.com>; Simon Horman <horms@kernel.org>; Shradha Gupta
> > > <shradhagupta@linux.microsoft.com>; Dipayaan Roy
> > > <dipayanroy@linux.microsoft.com>; Erni Sri Satya Vennela
> > > <ernis@linux.microsoft.com>; linux-kernel@vger.kernel.org; linux-
> > > pci@vger.kernel.org; Paul Rosswurm <paulros@microsoft.com>
> > > Subject: [EXTERNAL] Re: [PATCH net-next] net: mana: Add handler for sriov
> > > configure
> > > 
> > > On Fri, May 08, 2026 at 03:04:06PM -0700, Haiyang Zhang wrote:
> > > > From: Haiyang Zhang <haiyangz@microsoft.com>
> > > >
> > > > 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 :)

Bjorn,

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.

Thanks.

>