On Tue, Jul 28, 2015 at 05:23:22PM -0700, Andy Lutomirski wrote: > > PeterZ, can we fix this for real instead of relying on > CONFIG_PARAVIRT=y accidentally turning all msr accesses into "safe" > accesses? We have the CPUID "hypervisor" bit, but I still don't fully > understand the problem. So a whole bunch of PMU drivers already probe the MSRs at init time using a combination of rdmsrl_safe() and wrmsrl_safe() to see if: 1) its there at all 2) if its there, it 'works' like it ought to See for example: arch/x86/kernel/cpu/perf_event.c:check_hw_exists(). I have no problem using the _safe() methods to probe MSRs in init routines and failing the init of the driver etc. What I do object to is sprinkling _safe() all over the driver itself and creating horrid error paths all over (yes, people have proposed crazy things like that). Another example is the LBR probing in arch/x86/kernel/cpu/perf_event_intel.c:intel_pmu_init(). This is the one people wanted to use _safe() crud for all throughout the driver, instead of simply disabling the LBR at init time. As to the 'bug' at hand, I really don't see the problem. The RAPL driver says there's no valid RAPL domains, this is true, there aren't any on the virtual machine, so what? -- 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
