Re: [Qemu-devel] [PATCH V8 1/1] Guest stop notification

[Andreas Färber]

Am 06.04.2012 09:21, schrieb Raghavendra K T:
> From: Eric B Munson <address@hidden>
> 
> Often when a guest is stopped from the qemu console, it will report spurious
> soft lockup warnings on resume.  There are kernel patches being discussed that
> will give the host the ability to tell the guest that it is being stopped and
> should ignore the soft lockup warning that generates.  This patch uses the 
> qemu
> Notifier system to tell the guest it is about to be stopped.
> 
> Signed-off-by: Eric B Munson <address@hidden> 
> Signed-off-by: Raghavendra K T <address@hidden>
> 
> Cc: Eric B Munson <address@hidden>
> Cc: Avi Kivity <address@hidden> 
> Cc: Marcelo Tosatti <address@hidden>
> Cc: Anthony Liguori <address@hidden>
> Cc: Jan Kiszka <address@hidden>
> Cc: "Andreas FÀrber" <address@hidden>
> ---
> Changes from V7:
>  capabilty changed to KVM_CAP_KVMCLOCK_CTRL
>  KVM_GUEST_PAUSED is pervcpu again
>  CPUState renamed to CPUArchState

Thanks, change looks right to me.

Long-term I should probably consider supplying some cpu_foreach() macro
to iterate over them, but that would still need manual declaration of a
properly typed variable for the CPUArchState -> CPUState switch.

>  KVMCLOCK_GUEST_PAUSED changed to  KVM_KVMCLOCK_CTRL
> 
> Changes from V6:
>  Remove unnecessary include
> 
> Changes from V5:
>  KVM_GUEST_PAUSED is now a per vm ioctl instead of per vcpu
> 
> Changes from V4:
>  Test if the guest paused capability is available before use
> 
> Changes from V3:
>  Collapse new state change notification function into existsing function.
>  Correct whitespace issues
>  Change ioctl name to KVMCLOCK_GUEST_PAUSED
>  Use for loop to iterate vpcu's
> 
> Changes from V2:
>  Move ioctl into hw/kvmclock.c so as other arches can use it as it is
> implemented
> 
> Changes from V1:
>  Remove unnecessary encapsulating function
> ---
> 
> diff --git a/hw/kvm/clock.c b/hw/kvm/clock.c
> index 446bd62..c8a34a5 100644
> --- a/hw/kvm/clock.c
> +++ b/hw/kvm/clock.c
> @@ -64,10 +64,28 @@ static int kvmclock_post_load(void *opaque, int 
> version_id)
>  static void kvmclock_vm_state_change(void *opaque, int running,
>                                       RunState state)
>  {
> +    int ret;

Minor nitpick: We usually assign opaque values first thing in the
function, so maybe order ret last if you resend?

>      KVMClockState *s = opaque;
> +    CPUArchState *penv = first_cpu;
> +    int cap_clock_ctrl = kvm_check_extension(kvm_state, 
> KVM_CAP_KVMCLOCK_CTRL);
>  
>      if (running) {
>          s->clock_valid = false;
> +
> +        if (!cap_clock_ctrl) {
> +            return;
> +        }
> +        for (penv = first_cpu; penv != NULL; penv = penv->next_cpu) {
> +            ret = kvm_vcpu_ioctl(penv, KVM_KVMCLOCK_CTRL, 0);
> +            if (ret) {
> +                if (ret != -EINVAL) {
> +                    fprintf(stderr,
> +                            "kvmclock_vm_state_change: %s\n",
> +                            strerror(-ret));

I always recommend to use __func__. Otherwise looks okay to me.

Andreas

> +                }
> +                return;
> +            }
> +        }
>      }
>  }
>  

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