> On Tue, Jul 28, 2015 at 2:57 AM, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: >> >> >> On 27/07/2015 20:45, Andy Lutomirski wrote: >>> On Mon, Jul 27, 2015 at 11:30 AM, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: >>>> >>>> >>>> On 27/07/2015 19:51, Andy Lutomirski wrote: >>>>>>> I think I'm missing something. Does KVM_GUEST hook read_msr and >>>>>>> write_msr? I don't see it. >>>>>> >>>>>> PARAVIRT does, and it's the main reason why you'd want PARAVIRT for a >>>>>> KVM guest. >>>>> >>>>> Still confused. On a KVM guest (with PARAVIRT=y), doesn't read_msr do >>>>> exactly the same thing it does on native, albeit with more indirection >>>>> and patching involved? >>>> >>>> With PARAVIRT=y it never #GPs: >>>> >>>> .read_msr = native_read_msr_safe, >>>> .write_msr = native_write_msr_safe, >>>> >>>> I don't remember if it's this way on bare-metal too. >>> >>> Oh, whoops, I missed the "_safe". IMO that's just a bug, and I guess >>> KVM relies on it? >>> >>> ISTM the host should be fixed so that a non-PARAVIRT guest won't crash >>> when using perf (if it indeed currently crashes) >> >> It does. >> >>> and/or the perf code >>> should be fixed to work without this bug^Wfeature. >> >> You can call it even feature^Wbug, I won't take it personal. :) It does >> not prevent scary messages (such as "intel_rapl: no valid rapl domains >> found in package 0") in the logs for example. See >> https://bugzilla.redhat.com/show_bug.cgi?id=1178491 for a discussion >> about such scary messages. This bug is not openly readable. Which MSR accesses (in perf/etc) don't use safe {RD,WR}MSR accesses currently? -- vs; -- 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
