On Tue, 2012-08-21 at 11:34 +0300, Avi Kivity wrote: > On 08/21/2012 10:11 AM, Peter Zijlstra wrote: > > On Sun, 2012-08-19 at 12:55 +0300, Avi Kivity wrote: > >> > I think Avi prefers the method where KVM 'fakes' the MSRs and we have to > >> > detect if the MSRs actually work or not. > >> > >> s/we have/we don't have/. > > > > So for the 'normal' PMU we actually do check to see if the MSRs are > > being faked and bail if they are. > > That was because earlier versions of kvm did not virtualize the pmu. > > The approaches are not mutually exclusive. We can check in the guest, > and fake it in the host. This is actually what I proposed. > The problem with faking it in the host is if someone actually relies on > the pmu for something, not just instrumentation. We do that for the > watchdog, but I don't see it happening with the uncore pmu. Agreed, although from a usability POV its nicer to refuse the device/events than to pretend it works while it doesn't. Anyway, for now I've taken Zheng Yan's cpu_has_hypervisor patch, we can always revisit this. -- 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
