On Mon, Jul 27, 2015 at 6:59 AM, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > > > On 24/07/2015 19:33, Andy Lutomirski wrote: >> PARAVIRT adds a fair amount of bloat and, AFAICT, KVM_GUEST doesn't >> really need any of it. Would it make sense to drop the dependency? > > I think the main reason for PARAVIRT is that pv kernels have by default > > .read_msr = native_read_msr_safe, > .write_msr = native_write_msr_safe, > > Unfortunately Intel adds a bunch of performance measurement features > saying that "they work with this cpuid family/model/stepping" and at the > same time attach them to some non-architectural MSRs that, in principle > could be reused for something else years down the road. This is not a > huge problem for Windows, where only tools such as vTune use these MSRs, > but it is a problem for Linux. > > The alternative is ignore_msrs, but that's a very big hammer too. I think I'm missing something. Does KVM_GUEST hook read_msr and write_msr? I don't see it. Xen certainly needs those hooks, but I don't see why KVM would. --Andy -- 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
