Re: How to know that vPMU is enabled or disabled?

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Il 24/06/2014 10:33, Jidong Xiao ha scritto:
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.

This is correct.  QEMU only enables vPMU if you use "-cpu host".

Paolo
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