On Fri, Mar 30, 2018 at 4:49 AM, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:
> On Thu, Mar 29, 2018 at 11:22:31AM -0700, Jakub Kicinski wrote:
>> Some user space depends on driver allowing sriov_totalvfs to be
>> enabled.
>
> I can't make sene of this sentence. Can you explain what user space
> code depends on what semantics? The sriov_totalvfs file should show
> up for any device supporting SR-IOV as far as I can tell.
>
>>
>> For devices which VF support depends on loaded FW we
>> have the pci_sriov_{g,s}et_totalvfs() API. However, this API
>> uses 0 as a special "unset" value, meaning drivers can't limit
>> sriov_totalvfs to 0. Change the special value to be U16_MAX.
>> Use simple min() to determine actual totalvfs.
>
> Please use a PCI_MAX_VFS or similar define instead of plain U16_MAX or ~0.
Actually is there any reason why driver_max_VFs couldn't just be
initialized to the same value as total_VFs?
Also looking over the patch I don't see how writing ~0 would be
accepted unless you also make changes to pci_sriov_set_totalvfs since
it should fail the "numvfs > dev->sriov->total_VFs" check. You might
just want to look at adding a new function that would reset the
driver_max_VFs value instead of trying to write it to an arbitrary
value from the driver.
- Alex
