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

Alexander Graf agraf at suse.de
Sun Jun 27 19:38:43 EST 2010


Am 27.06.2010 um 10:16 schrieb Avi Kivity <avi at redhat.com>:

> 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



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