Re: [Qemu-devel] [PATCH v2 1/8] kvm: Set cpu_single_env only once

[Blue Swirl]

On Sat, Feb 11, 2012 at 12:43, Jan Kiszka <address@hidden> wrote:
> On 2012-02-11 12:49, Andreas Färber wrote:
>> Am 11.02.2012 12:25, schrieb Blue Swirl:
>>> I think using cpu_single_env is an indication of a problem, like poor
>>> code, layering violation or poor API (vmport). What is your use case?
>>
>> I couldn't spot any in this series. Jan, note that any new use of env or
>> cpu_single_env will need to be redone when we convert to QOM CPU.
>
> cpu_single_env should have nothing to do with QOM.
>
> The ABIs of vmport and the KVM VAPI require a reference to the calling
> VCPU, and that's why you find tons of them in patch 5.

Yes, this seems to be another case of a badly designed ABI. I guess
there is no way to change that anymore, just like vmport?

Some of the cpu_single_env accesses in patch 5 could be avoided when
APIC is moved closer to CPU. VAPIC should be also close to APIC so it
should be able to access the CPU directly. In some other cases the
current state could be passed around instead once it is known.

>
> Jan
>