On 2016-07-09 13:44:03 [-0600], Alex Williamson wrote: > The root port device IDs translate to a Skylake platform, which is a > "client" processor. Core-i3/5/7 and even Xeon E3 fit into this It is an E3-1230 v5 > category and they do not support ACS on the processor root ports. This > groups everything downstream of those root ports together and even > binds together separate sub-hierarchies when the root ports are joined > in a multifunction slot. Without ACS we cannot guarantee that > peer-to-peer DMA does not occur through redirection prior to IOMMU > translation. So it is not a missing BIOS knob but a missing CPU feature. > The easiest solution is to move the card to one of the PCH sourced root > ports (ie. downstream of root ports at 00:1c.*). As of kernel v4.7-rc1 > we have quirks for the Sunrise Point PCH to work around the botched > implementation of ACS found in this chipset. Pretty much all Intel > client processors have the same story, no ACS in the processor root > ports, quirks to enable ACS in the PCH root ports. Xeon E5 and higher > as well as "High End Desktop Processors" (based on E5) support ACS > correctly (though the PCH root ports need and already have quirks for > ACS). bah. Not sure if another slot is possible / available but thanks for the hint. > There exists a non-upstream patch to override ACS, which does nothing > to solve the isolation problem, it just allows you to gamble with data > integrity, which is why it really has no place upstream. The IGB > devices you note in pci_dev_acs_enabled are quirks for the IGB PFs. > Intel has confirmed that there is isolation between the PFs, so when > installed into topology that does have ACS support, this allows the PFs > to be put into separate groups. Since the point at which your system > lacks isolation is upstream of the PFs, this doesn't help you. Thanks, Thank you for the explanation. > Alex Sebastian -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
