Re: [PATCH 02/26] KVM: PPC: Convert MSR to shared page

Alexander Graf
2010-06-27T09:38:43Z

Am 27.06.2010 um 10:16 schrieb Avi Kivity <avi-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>:

> On 06/26/2010 02:24 AM, Alexander Graf wrote:
>> One of the most obvious registers to share with the guest directly
>> is the
>> MSR. The MSR contains the "interrupts enabled" flag which the guest
>> has to
>> toggle in critical sections.
>>
>> So in order to bring the overhead of interrupt en- and disabling
>> down, let's
>> put msr into the shared page. Keep in mind that even though you can
>> fully read
>> its contents, writing to it doesn't always update all state. There
>> are a few
>> safe fields that don't require hypervisor interaction. See the guest
>> implementation that follows later for reference.
>>
>
>
> You mean, see the documentation for reference.
>
> It should be possible to write the guest code looking only at the
> documentation.

*shrug* since we're writing open source I don't mind telling people to
read code for a reference implemenration. If well written, that's more
comprehensible than documentation anyways :).

But either way, you can take a look at both - documentation and code,
yes.

What I really meant here is that the list of registers we patch should
be taken from the patch code. I didn't want to write out all of them
in the description.

Alex