On Mon, Jun 23, 2014 at 1:41 PM, Jidong Xiao <jidong.xiao@xxxxxxxxx> wrote: > Hi, All, > > I am using a virtual machine in a cloud environment, which means I am > in control of the Guest OS, but have no access to the Host OS. Is > there a simple way to know whether or not the vPMU is enabled or > disabled? Or, is there something I can control so as to turn its state > from enable to disable, or vice versa? Thanks. > I think I have figured out this. According to this patch (as well as the Intel SDM manual), it looks like pmu is exposed via the cpuid leaf 0xah. https://github.com/torvalds/linux/commit/a6c06ed1a60aff77b27ba558c315c3fed4e35565 Therefore, in the guest os, one can run the cpuid instruction with leaf 0xa, and if vpmu is supported/enabled, the return value in eax/ebx/ecx/edx should be something non-zero, and in the cloud machine which I am using I see these registers are all zero, therefore I think vpmu is not supported in my virtual machine. Probably it is masked by Qemu. -Jidong -- 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
