Messages in this thread | ![/](/images/icornerl.gif) | | Date | Fri, 21 Jun 2019 10:48:25 -0700 | From | Andi Kleen <> | Subject | Re: [RFC] perf/x86/intel: Disable check_msr for real hw |
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On Fri, Jun 14, 2019 at 01:28:53PM +0200, Jiri Olsa wrote: > hi, > the HPE server can do POST tracing and have enabled LBR > tracing during the boot, which makes check_msr fail falsly. > > It looks like check_msr code was added only to check on guests > MSR access, would it be then ok to disable check_msr for real > hardware? (as in patch below) > > We could also check if LBR tracing is enabled and make > appropriate checks, but this change is simpler ;-) > > ideas? thanks, > jirka
Sorry for the late comment. I see this patch has been merged now.
Unfortunately I don't think it's a good idea. The problem is that the hypervisor flags are only set for a few hypervisors that Linux knows about. But in practice there are many more Hypervisors around that will not cause these flags to be set. But these are still likely to miss MSRs.
The other hypervisors are relatively obscure, but eventually someone will hit problems.
-Andi
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