Re: [Qemu-devel] [PATCH V3] Guest stop notification

[Jan Kiszka <jan.kiszka@web.de>]

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On 2011-12-02 20:19, Eric B Munson wrote:
> 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.
> 
> Signed-off-by: Eric B Munson <emunson@mgebm.net>
> Cc: Avi Kivity <avi@redhat.com>
> Cc: Marcelo Tosatti <mtosatti@redhat.com>
> Cc: Jan Kiszka <jan.kiszka@siemens.com>
> Cc: ryanh@linux.vnet.ibm.com
> Cc: aliguori@us.ibm.com
> Cc: kvm@vger.kernel.org
> 
> ---
> 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
> 
>  hw/kvmclock.c |   24 ++++++++++++++++++++++++
>  1 files changed, 24 insertions(+), 0 deletions(-)
> 
> diff --git a/hw/kvmclock.c b/hw/kvmclock.c
> index 5388bc4..756839f 100644
> --- a/hw/kvmclock.c
> +++ b/hw/kvmclock.c
> @@ -16,6 +16,7 @@
>  #include "sysbus.h"
>  #include "kvm.h"
>  #include "kvmclock.h"
> +#include "cpu-all.h"
>  
>  #include <linux/kvm.h>
>  #include <linux/kvm_para.h>
> @@ -69,11 +70,34 @@ static void kvmclock_vm_state_change(void *opaque, int running,
>      }
>  }
>  
> +static void kvmclock_vm_state_change_vcpu(void *opaque, int running,
> +                                          RunState state)
> +{
> +    int ret;
> +    CPUState *penv = first_cpu;
> +
> +    if (running) {
> +	while (penv) {

or: for (cpu = first_cpu; cpu != NULL; cpu = cpu->next_cpu) {

> +            ret = kvm_vcpu_ioctl(penv, KVM_GUEST_PAUSED, 0);
> +            if (ret) {
> +                if (ret != ENOSYS) {
> +                    fprintf(stderr,
> +                            "kvmclock_vm_state_change_vcpu: %s\n",
> +                            strerror(-ret));
> +                }
> +                return;
> +            }
> +            penv = (CPUState *)penv->next_cpu;

Unneeded cast.

> +        }
> +    }
> +}
> +

Again: please use checkpatch.pl.

>  static int kvmclock_init(SysBusDevice *dev)
>  {
>      KVMClockState *s = FROM_SYSBUS(KVMClockState, dev);
>  
>      qemu_add_vm_change_state_handler(kvmclock_vm_state_change, s);
> +    qemu_add_vm_change_state_handler(kvmclock_vm_state_change_vcpu, NULL);
>      return 0;
>  }
>  

Why not extend the existing handler?

I still wonder if the IOCTL interface is actually kvmclock specific. But
Marcello asked for this, and we could still change it when some arch
comes around that provides it independent of kvmclock.

Jan


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