Re: [PATCH RFC V3 2/4] kvm hypervisor : Add a hypercall to KVMhypervisor to support pv-ticketlocks

[Marcelo Tosatti]

On Wed, Dec 07, 2011 at 02:47:05PM +0200, Avi Kivity wrote:
> On 12/07/2011 02:33 PM, Marcelo Tosatti wrote:
> > > 
> > > Also Avi pointed that, logically kvm_arch_vcpu_ioctl_set_mpstate should
> > > be called only in vcpu thread, so after further debugging, I noticed
> > > that,  setting vcpuN->mp_state = KVM_MP_STATE_RUNNABLE; is not
> > > necessary.
> > > I 'll remove that in the next patch. Thanks for pointing.
> >
> > In fact you don't need kvm_arch_vcpu_ioctl_set_mpstate either, only the
> > new "kicked" flag.
> 
> If we have a kicked flag, it becomes necessary to live migrate it.
> 
> Maybe we can change KVM_GET_MP_STATE to fold the kicked flag into the mp
> state (converting HALTED into RUNNABLE).

Yep, that works.

> Also I think we can keep the kicked flag in vcpu->requests, no need for
> new storage.

Was going to suggest it but it violates the currently organized
processing of entries at the beginning of vcpu_enter_guest.

That is, this "kicked" flag is different enough from vcpu->requests
processing that a separate variable seems worthwhile (even more
different with convertion to MP_STATE at KVM_GET_MP_STATE).

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