[Qemu-devel] Re: [PATCH v2 0/11]

[Jan Kiszka]

Gleb Natapov wrote:
> On Tue, Dec 01, 2009 at 10:51:26AM -0200, Glauber Costa wrote:
>> This is a repost of the -smp series. Note that it depends on 
>> irqchip-in-kernel,
>> that is already in staging. Also, you'll have to enable the io-thread, for 
>> the time
>> being.
>>
>> >From the last version, main change is that I am not calling queue_work 
>> >automatically
>> from vcpu ioctls. queue_work is only used currently for the gdb stub.
>>
>> All other uses were by-passed by the new qemu_register_vcpu_reset(), since 
>> most
>> of it uses (all racy) came from the reset handlers.
>>
> Looks good to me except one thing. I don't see how you are addressing
> the problem fixed by commit b8a7857071b477b28d3055e33ff0298fc91f329a
> in qemu-kvm. The problem is that mp_state can change in kernel between
> call to kvm_cpu_synchronize_state() and vcpu re-entry. In this case old
> mp_state will overwrite new one.

+ nmi_pending
+ sipi_vector

These things need to be fixed at kernel level as discussed recently:
Asynchronous changes done by in-kernel subsystems need to be queued and
replayed with a higher priority than user space changes. User space need
to stop the vm if it does not want to be overruled.

Jan

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