Re: Having troubles binding an SR-IOV VF to uio_pci_generic on Amazon instance

[Vlad Zolotarov <vladz@cloudius-systems.com>]

On 10/01/15 17:47, Stephen Hemminger wrote:
> On Thu, 1 Oct 2015 11:00:28 +0300
> Vlad Zolotarov <vladz@cloudius-systems.com> wrote:
>
>>
>> On 10/01/15 00:36, Stephen Hemminger wrote:
>>> On Wed, 30 Sep 2015 23:09:33 +0300
>>> Vlad Zolotarov <vladz@cloudius-systems.com> wrote:
>>>
>>>> On 09/30/15 22:39, Michael S. Tsirkin wrote:
>>>>> On Wed, Sep 30, 2015 at 10:06:52PM +0300, Vlad Zolotarov wrote:
>>>>>>>> How would iommu
>>>>>>>> virtualization change anything?
>>>>>>> Kernel can use an iommu to limit device access to memory of
>>>>>>> the controlling application.
>>>>>> Ok, this is obvious but what it has to do with enabling using MSI/MSI-X
>>>>>> interrupts support in uio_pci_generic? kernel may continue to limit the
>>>>>> above access with this support as well.
>>>>> It could maybe. So if you write a patch to allow MSI by at the same time
>>>>> creating an isolated IOMMU group and blocking DMA from device in
>>>>> question anywhere, that sounds reasonable.
>>>> No, I'm only planning to add MSI and MSI-X interrupts support for
>>>> uio_pci_generic device.
>>>> The rest mentioned above should naturally be a matter of a different
>>>> patch and writing it is orthogonal to the patch I'm working on as has
>>>> been extensively discussed in this thread.
>>>>
>>> I have a generic MSI and MSI-X driver (posted earlier on this list).
>>> About to post to upstream kernel.
>> Stephen, hi!
>>
>> I found the mentioned series and first thing I noticed was that it's
>> been sent in May so the first question is how far in your list of tasks
>> submitting it upstream is? We need it more or less yesterday and I'm
>> working on it right now. Therefore if u don't have time for it I'd like
>> to help... ;) However I'd like u to clarify a few small things. Pls.,
>> see below...
>>
>> I noticed that u've created a separate msi_msix driver and the second
>> question is what do u plan for the upstream? I was thinking of extending
>> the existing uio_pci_generic with the MSI-X functionality similar to
>> your code and preserving the INT#X functionality as it is now:
> The igb_uio has a bunch of other things I didn't want to deal with:
> the name (being specific to old Intel driver); compatibility with older
> kernels; legacy ABI support. Therefore in effect uio_msi is a rebase
> of igb_uio.
>
> The submission upstream yesterday is the first step, I expect lots
> of review feedback.

Sure, we have lots of feedback already even before the patch has been 
sent... ;)
So, I'm preparing the uio_pci_generic patch. Just wanted to make sure we 
are not working on the same patch at the same time... ;)

It's going to enable both MSI and MSI-X support.
For a backward compatibility it'll enable INT#X by default.
It follows the concepts and uses some code pieces from your uio_msi 
patch. If u want I'll put u as a signed-off when I send it.


>
>>    *   INT#X and MSI would provide the IRQ number to the UIO module while
>>      only MSI-X case would register with UIO_IRQ_CUSTOM.
> I wanted all IRQ's to be the same for the driver, ie all go through
> eventfd mechanism. This makes code on DPDK side consistent with less
> special cases.

Of course. The name (uio_msi) is a bit confusing since it only adds 
MSI-X support. I mistakenly thought that it adds both MSI and MSI-X but 
it seems to only add MSI-X and then there are no further questions... ;)

>
>> I also noticed that u enable MSI-X on a first open() call. I assume
>> there was a good reason (that I miss) for not doing it in probe(). Could
>> u, pls., clarify?

What about this?