Messages in this thread | | | Date | Fri, 21 Mar 2014 14:55:24 -0700 | From | "H. Peter Anvin" <> | Subject | Re: GPF in intel_pmu_lbr_reset() with qemu -cpu host |
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On 03/21/2014 02:48 PM, Andi Kleen wrote: > "H. Peter Anvin" <hpa@zytor.com> writes: >> >> That's why at least to some extent The Right Thing is not to try to >> pretend to be a CPU you don't even know how to emulate. >> >> But again, that has its own issues, too, mostly with userspace >> optimization, and making the Linux code more resilient wouldn't hurt. >> In that sense #GP(0) is *much* better than 0: it unambiguously gives an >> error to work with. > > That means we could just throw rdmsr() away and it would be completely > replaced with rdmsr_safe(). But then that will likely cause all kinds > of problems with how to handle these errors and where and how to handle > these exceptions. > > I much prefer just to fix KVM. I cannot think of any case > where 0 would cause a major issue. > > After all it's virtualization not "rewrite complete kernel for it" >
Actually, Ingo, Borislav and I have been discussing making rdmsr_safe() more of the default, especially for things like this where the error handling is obvious (doesn't work? Disable the PMU.)
-hpa
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