Messages in this thread | | | Date | Fri, 4 Dec 2015 09:22:56 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH] x86/rapl: Do not load in a guest |
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On Fri, Dec 04, 2015 at 08:42:06AM +0100, Ingo Molnar wrote: > > * Borislav Petkov <bp@alien8.de> wrote: > > > From: Borislav Petkov <bp@suse.de> > > > > qemu/kvm doesn't support RAPL and RAPL doesn't have a CPUID feature bit > > so check whether we're in a guest instead. > > So when a hypervisor starts supporting RAPL we'll disable the driver erroneously? > > Isn't there any better method to detect RAPL support? > > So in particular in drivers/powercap/intel_rapl.c there's an enumerated list of > CPU models, which is used via a x86_match_cpu() call. That's still not ideal (it > does not work on hypervisors for example), but even better would be to detect RAPL > support in some other fashion, that does not rely on us statically enumerating CPU > models that support it.
RAPL isn't enumerated, the best we could do is attempt to write to one of the writable MSRs and see if that 'works'.
Also, yuck @ powercap/intel_rapl.c for doing rdmsr_on_cpu() + wrmsr_on_cpu() all over the place.
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