Paolo Bonzini <pbonzini <at> redhat.com> writes:
>
>
> On 21/10/2015 00:57, Wanpeng Li wrote:
> >> kvm_sched_out and kvm_sched_in are part of KVM's preemption hooks. The
> >> hooks are registered only between vcpu_load and vcpu_put, therefore they
> >> know that the mutex is taken. The sequence will go like this:
> >>
> >> vcpu_load
> >> kvm_sched_out
> >> kvm_sched_in
> >> kvm_sched_out
> >> kvm_sched_in
> >> ...
> >> vcpu_put
> >
> > If this should be:
> >
> > vcpu_load
> > kvm_sched_in
> > kvm_sched_out
> > kvm_sched_in
> > kvm_sched_out
> > ...
> > vcpu_put
>
> No, because vcpu_load is called while the thread is running. Therefore,
> the first preempt notifier call will be a sched_out notification, which
> calls kvm_arch_vcpu_put. Extending the picture above:
>
> vcpu_load -> kvm_arch_vcpu_load
> kvm_sched_out -> kvm_arch_vcpu_put
> kvm_sched_in -> kvm_arch_vcpu_load
> kvm_sched_out -> kvm_arch_vcpu_put
> kvm_sched_in -> kvm_arch_vcpu_load
> ...
> kvm_sched_out -> kvm_arch_vcpu_put
> kvm_sched_in -> kvm_arch_vcpu_load
> vcpu_put -> kvm_arch_vcpu_put
>
> Thanks,
>
> Paolo
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>
>
Thanks for the explanation, it's very clear.
I tired that but I didn't succeed to send the ioctl from "run_on_cpu"
function, I didn't find how to set the right CPUStat
I've tried "current_cpu"
kvm_main.c:
// yacine.begin
static void do_vmi_start_kvm_ioctl(void *type) {
printf("do_vmi_start_kvm_ioctl\n");
kvm_vm_ioctl(kvm_state, type);
}
int vmi_start_kvm_ioctl(int type) { <- called from hmp.c
printf("vmi_start_kvm_ioctl\n");
run_on_cpu(current_cpu, do_vmi_start_kvm_ioctl, (void *) &type);
return 0;
}
// yacine.end
This gives me a segmentation fault
Then I tired to replace current_cpu with ENV_GET_CPU(mon_get_cpu()), it
didn't work, I get nothing, no error but doesn't work
I tried also to pass mon->mon_cpu through int vmi_start_kvm_ioctl(int type)
by adding a first parameter as CPUStat, i get compiler error "dereference
pointer to incomplete type"
I'm beginner to qemu and kvm code, can you please orient me to fix this
problem ? Thanks in advance
Yacine
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