Re: [PATCH] PCI: handle pci_sriov_set_totalvfs(dev, 0)

[Edward Cree <ecree@solarflare.com>]

On 31/07/14 18:53, Don Dutile wrote:
> On 07/31/2014 12:57 PM, Edward Cree wrote:
>> Alas, it's (once again) more complicated than that.  There's another
>> mode, NIC partitioning, which has multiple PFs per port but connected
>> with a VLAN aggregator rather than a v-switch, which means that each PF
>> then can support VFs (the firmware limitation is that v-switches can't
>> be stacked).
>> So having multiple PFs on the port doesn't necessarily mean we can't do
>> SR-IOV.
>>
> Ed,
> It is fairly obvious that your PCIe device operates in very unexpected,
> non-std modes.
I really don't think it does.  As far as PCIe is concerned, the device
is behaving perfectly sanely: it claims to support VFs, and it does
support VFs.  You can add the VFs as PCIe functions just fine.  It's
just that the higher-layer entities those VFs give access to don't work
properly.

> Ignore twiddling total-vfs, and just have the driver fail sriov
> configuration when they can operate, print a warning why, and let's
> not create
> complicated/convoluted hacks dependent on the use of various
> assumptions/uses
> of pdev flags.
I don't like the idea of failing sriov configuration (I assume by this
you mean the pci_driver.sriov_configure function), simply because we
know at PF probe time that VFs won't work - so why advertise them?  We
have a pci_sriov_set_totalvfs function, why shouldn't it be used here?

> Ideally, when the device is configured in different modes, the SRIOV
> cap structure
> should be modified so the pci sriov code doesn't try to act or reflect
> the
> non-reality the device is in.
That would be much nicer of course, and I'll ask our firmware team if
that's possible.  But I don't think it will be.

-Edward
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