I would virtualize the "ATS Control Register". Regarding poor behavior, I couldn't really find what happens when ATS is misconfigured, but I would assume it can cause problems. The scenarios I'm concerned about are: 1. The guest enables translation caching, while the hypervisor thinks there are disabled -> Hypervisor won't issue invalidations. 2. Smallest Translation Unit misconfiguration. Not sure if it will cause invalid access or only poor caching behavior. Thanks, Ilya > -----Original Message----- > From: Alex Williamson [mailto:alex.williamson@xxxxxxxxxx] > Sent: Sunday, November 06, 2016 7:09 PM > To: Ilya Lesokhin <ilyal@xxxxxxxxxxxx> > Cc: linux-pci@xxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; bhelgaas@xxxxxxxxxx > Subject: Re: Shouldn't VFIO virtualize the ATS capability? > > On Sun, 6 Nov 2016 11:13:09 +0000 > Ilya Lesokhin <ilyal@xxxxxxxxxxxx> wrote: > > > Hi > > I've noticed that VFIO doesn't virtualize the ATS capability. > > It seems to me that translation caching and Smallest Translation Unit is > something you would want to control on the host. Am I wrong? > > What about those fields would we virtualize? Why does the host need to be > an intermediary? Can the user induce poor behavior with direct access to > them? Thanks, > > Alex -- 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
