Re: [PATCH] iommu: amd/intel: Remove multifunction assumption aroundgrouping

From: Joerg Roedel
Date: Thu Jun 20 2013 - 11:23:01 EST

On Thu, May 30, 2013 at 12:39:18PM -0600, Alex Williamson wrote:
> If a device is multifunction and does not have ACS enabled then we
> assume that the entire package lacks ACS and use function 0 as the
> base of the group. The PCIe spec however states that components are
> permitted to implement ACS on some, none, or all of their applicable
> functions. It's therefore conceivable that function 0 may be fully
> independent and support ACS while other functions do not. Instead
> use the lowest function of the slot that does not have ACS enabled
> as the base of the group. This may be the current device, which is
> intentional. So long as we use a consistent algorithm, all the
> non-ACS functions will be grouped together and ACS functions will
> get separate groups.
> Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> ---
> drivers/iommu/amd_iommu.c | 25 +++++++++++++++++++------
> drivers/iommu/intel-iommu.c | 25 +++++++++++++++++++------

Didn't really fit into any of my existing branches. Applied it to
x86/vt-d because it is probably not worth creating a new x86-specific
branch just for this patch.



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