On Mon, 2011-08-22 at 09:30 +0300, Avi Kivity wrote: > On 08/20/2011 07:51 PM, Alex Williamson wrote: > > We need to address both the description and enforcement of device > > groups. Groups are formed any time the iommu does not have resolution > > between a set of devices. On x86, this typically happens when a > > PCI-to-PCI bridge exists between the set of devices and the iommu. For > > Power, partitionable endpoints define a group. Grouping information > > needs to be exposed for both userspace and kernel internal usage. This > > will be a sysfs attribute setup by the iommu drivers. Perhaps: > > > > # cat /sys/devices/pci0000:00/0000:00:19.0/iommu_group > > 42 > > > > $ readlink /sys/devices/pci0000:00/0000:00:19.0/iommu_group > ../../../path/to/device/which/represents/the/resource/constraint > > (the pci-to-pci bridge on x86, or whatever node represents partitionable > endpoints on power) The constraint might not necessarily be a device. The PCI bridge is just an example. There are other possible constraints. On POWER for example, it could be a limit in how far I can segment the DMA address space, forcing me to arbitrarily put devices together, or it could be a similar constraint related to how the MMIO space is broken up. So either that remains a path in which case we do have a separate set of sysfs nodes representing the groups themselves which may or may not itself contain a pointer to the "constraining" device, or we just make that an arbitrary number (in my case the PE#) Cheers, Ben -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
