Re: [Qemu-devel] [PATCH 6/6] kvm_stat: Add powerpc support

[Alexander Graf <agraf@suse.de>]

On 18.06.14 03:37, Michael Ellerman wrote:
> On Wed, 2014-06-18 at 02:59 +0200, Alexander Graf wrote:
>> On 18.06.14 02:50, Michael Ellerman wrote:
>>> On Tue, 2014-06-17 at 10:27 +0200, Alexander Graf wrote:
>>>> On 17.06.14 09:54, Michael Ellerman wrote:
>>>>> Add support for powerpc platforms. We use uname -m, which allows us to
>>>>> detect ppc, ppc64 and ppc64le/el.
>>>>>
>>>>> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
>>>> Could you please add support for PR KVM tracepoints along the way? There
>>>> we do know the exit reason for every single guest <-> host transition. I
>>>> would like to move to a similar model with HV in the future, so we can
>>>> hopefully just reuse this by then.
>>> So I think what you're saying is you want it to somehow support using
>>> 'kvm_exit' for PR and 'kvm_userspace_exit' for HV?
>> "kvm_userspace_exit" is implemented on both HV and PR. "kvm_exit" is PR
>> only, but I'm hoping we can get it working in HV as well.
>>
>>> Or actually use 'kvm_exit' if it exists and fall back to 'kvm_userspace_exit',
>>> so that if HV starts providing 'kvm_exit' the script will pick that up without
>>> further changes.
>> They are completely different things. "kvm_userspace_exit" tells us
>> which exits we take from KVM -> QEMU. "kvm_exit" tells us which exits we
>> take from guest -> KVM.
>>
>> In fact, IIRC x86 also implements kvm_userspace_exit - or at least
>> something very similar to it. It's a completely separate category.
> Right. Everyone implements kvm_userspace_exit, it's in virt/kvm/kvm_main.c
>
>> Maybe it should be a command line switch to distinguish between the count types?
> Or just we always read the kvm_userspace_exit counts, and if we find kvm_exit
> we expose that as well - with an arch specific set of reasons.

That would work too. I'm not sure how interesting the exit count of 
kvm_userspace_exit really is, but it certainly works for me to have it 
available as well.


Alex