vfio: missing patch in linux 3.6

vfio: missing patch in linux 3.6

[Andreas Hartmann]

Hello Alex,

I just tested vfio as part of linux 3.6 and detected, that it doesn't
work because of the following missing patch:

http://news.gmane.org/find-root.php?group=gmane.linux.kernel.pci&article=16422

Could you please get it applied for the next stable release?


Thanks,
kind regards,
Andreas Hartmann

Re: vfio: missing patch in linux 3.6

[Alex Williamson]

On Thu, 2012-10-04 at 17:13 +0200, Andreas Hartmann wrote:
> Hello Alex,
> 
> I just tested vfio as part of linux 3.6 and detected, that it doesn't
> work because of the following missing patch:
> 
> http://news.gmane.org/find-root.php?group=gmane.linux.kernel.pci&article=16422
> 
> Could you please get it applied for the next stable release?

Hi Andreas,

This patch needs to go through Bjorn's PCI tree, but as noted in the
comments I have some outstanding questions that need to be answered,
probably by Joerg.  Thanks,

Alex

Re: vfio: missing patch in linux 3.6

[Andreas Hartmann]

Alex Williamson wrote:
> On Thu, 2012-10-04 at 17:13 +0200, Andreas Hartmann wrote:
>> Hello Alex,
>> 
>> I just tested vfio as part of linux 3.6 and detected, that it
>> doesn't work because of the following missing patch:
>> 
>> http://news.gmane.org/find-root.php?group=gmane.linux.kernel.pci&article=16422
>>
>>
>> 
Could you please get it applied for the next stable release?
> 
> Hi Andreas,
> 
> This patch needs to go through Bjorn's PCI tree, but as noted in
> the comments I have some outstanding questions that need to be
> answered, probably by Joerg.  Thanks,

Sorry Alex,
I missed your additional questions because this patch just works
pretty fine here with kernel 3.4.x.

But you're right, your questions should be resolved before freeing it
to the wild.

@Joerg:
Please, liberate me from compiling and patching each kernel myself to
get it working and give all the other users out there a chance to use
this pretty code and the IOMMU support of AMD's hardware :-) by
answering Alex' questions.


Thanks,
kind regards,
Andreas

Re: vfio: missing patch in linux 3.6

[Roedel, Joerg]

On Thu, Oct 04, 2012 at 09:26:39AM -0600, Alex Williamson wrote:
> On Thu, 2012-10-04 at 17:13 +0200, Andreas Hartmann wrote:
> > Hello Alex,
> > 
> > I just tested vfio as part of linux 3.6 and detected, that it doesn't
> > work because of the following missing patch:
> > 
> > http://news.gmane.org/find-root.php?group=gmane.linux.kernel.pci&article=16422
> > 
> > Could you please get it applied for the next stable release?
> 
> Hi Andreas,
> 
> This patch needs to go through Bjorn's PCI tree, but as noted in the
> comments I have some outstanding questions that need to be answered,
> probably by Joerg.  Thanks,

What are the open questions? I have confirmation from the hardware
people that the south bridges are peer-2-peer safe. Other questions?


	Joerg

-- 
AMD Operating System Research Center

Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach
General Managers: Alberto Bozzo
Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632

Re: vfio: missing patch in linux 3.6

[Alex Williamson]

On Thu, 2012-10-04 at 18:14 +0200, Roedel, Joerg wrote:
> On Thu, Oct 04, 2012 at 09:26:39AM -0600, Alex Williamson wrote:
> > On Thu, 2012-10-04 at 17:13 +0200, Andreas Hartmann wrote:
> > > Hello Alex,
> > > 
> > > I just tested vfio as part of linux 3.6 and detected, that it doesn't
> > > work because of the following missing patch:
> > > 
> > > http://news.gmane.org/find-root.php?group=gmane.linux.kernel.pci&article=16422
> > > 
> > > Could you please get it applied for the next stable release?
> > 
> > Hi Andreas,
> > 
> > This patch needs to go through Bjorn's PCI tree, but as noted in the
> > comments I have some outstanding questions that need to be answered,
> > probably by Joerg.  Thanks,
> 
> What are the open questions? I have confirmation from the hardware
> people that the south bridges are peer-2-peer safe. Other questions?

Hi Joerg,

There are a couple questions in the link above.  Since the devices don't
expose a PCIe capability, we probably need to add a check to look at the
upstream device and verify we're not on a legacy bus where ACS can't be
enforced.  Then there's the general question of whether the confirmation
of no peer-to-peer applies to every case where we might see this device
(some of them seem to have history that pre-dates this specific package
implementation) or do we need to try to identify specific package
properties in addition to just a device ID?  Thanks,

Alex

Re: vfio: missing patch in linux 3.6

[Roedel, Joerg]

On Thu, Oct 04, 2012 at 10:28:00AM -0600, Alex Williamson wrote:
> There are a couple questions in the link above.  Since the devices don't
> expose a PCIe capability, we probably need to add a check to look at the
> upstream device and verify we're not on a legacy bus where ACS can't be
> enforced.

You can certainly do that, but for existing hardware (with an AMD IOMMU)
this check would never be true. These devices are always on a seperate
south-bridge chip which is connected to the north-bridge via PCIe. So
the topology where you find these devices is always the same in an AMD
IOMMU system.

> Then there's the general question of whether the confirmation
> of no peer-to-peer applies to every case where we might see this device
> (some of them seem to have history that pre-dates this specific package
> implementation) or do we need to try to identify specific package
> properties in addition to just a device ID?

The device ids are kept the same to maintain compatability with older
software. Besides that, my statement about the peer-2-peer safety is
true for all south-bridges that you can find in an AMD IOMMU capable
system.

Regards,

	Joerg

-- 
AMD Operating System Research Center

Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach
General Managers: Alberto Bozzo
Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632

Re: vfio: missing patch in linux 3.6

[Andreas Hartmann]

Roedel, Joerg wrote:
> On Thu, Oct 04, 2012 at 10:28:00AM -0600, Alex Williamson wrote:
>> There are a couple questions in the link above.  Since the devices don't
>> expose a PCIe capability, we probably need to add a check to look at the
>> upstream device and verify we're not on a legacy bus where ACS can't be
>> enforced.
> 
> You can certainly do that, but for existing hardware (with an AMD IOMMU)
> this check would never be true. These devices are always on a seperate
> south-bridge chip which is connected to the north-bridge via PCIe. So
> the topology where you find these devices is always the same in an AMD
> IOMMU system.
> 
>> Then there's the general question of whether the confirmation
>> of no peer-to-peer applies to every case where we might see this device
>> (some of them seem to have history that pre-dates this specific package
>> implementation) or do we need to try to identify specific package
>> properties in addition to just a device ID?
> 
> The device ids are kept the same to maintain compatability with older
> software. Besides that, my statement about the peer-2-peer safety is
> true for all south-bridges that you can find in an AMD IOMMU capable
> system.

http://news.gmane.org/find-root.php?group=gmane.linux.kernel.pci&article=16422

I think, Joerg wrote clearly that there is no problem any more to apply
this patch. I run it since a long time meanwhile without any problem.
Please, why aren't these patches applied?


Thanks,
kind regards,
Andreas Hartmann