Re: [Qemu-devel] [PATCH V7] Guest stop notification

[Alexander Graf]

On 27.01.2012, at 22:49, Jan Kiszka <address@hidden> wrote:

> On 2012-01-27 21:48, Anthony Liguori wrote:
>> On 01/17/2012 12:27 PM, 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.  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>
>>> 
>>> Cc: Avi Kivity<address@hidden>
>>> Cc: Marcelo Tosatti<address@hidden>
>>> Cc: Jan Kiszka<address@hidden>
>>> Cc: address@hidden
>>> Cc: address@hidden
>>> Cc: address@hidden
>>> ---
>>> 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
>>> 
>>>  hw/kvmclock.c |   11 +++++++++++
>>>  1 files changed, 11 insertions(+), 0 deletions(-)
>>> 
>>> diff --git a/hw/kvmclock.c b/hw/kvmclock.c
>>> index 3b9fb20..ad79f52 100644
>>> --- a/hw/kvmclock.c
>>> +++ b/hw/kvmclock.c
>>> @@ -64,10 +64,21 @@ static int kvmclock_post_load(void *opaque, int
>>> version_id)
>>>  static void kvmclock_vm_state_change(void *opaque, int running,
>>>                                       RunState state)
>>>  {
>>> +    int ret;
>>>      KVMClockState *s = opaque;
>>> +    int cap_guest_paused = kvm_check_extension(kvm_state,
>>> KVM_CAP_GUEST_PAUSED);
>>> 
>>>      if (running) {
>>>          s->clock_valid = false;
>>> +
>>> +        if (!cap_guest_paused) {
>>> +            return;
>>> +        }
>>> +
>>> +        ret = kvm_vm_ioctl(kvm_state, KVMCLOCK_GUEST_PAUSED, 0);
>>> +        if (ret) {
>>> +            fprintf(stderr, "kvmclock_vm_state_change: %s\n",
>>> strerror(-ret));
>>> +        }
>>>      }
>>>  }
>> 
>> 
>> This change looks harmless enough.
> 
> Yep, but needs to be redirected after the file renaming in upstream.
> 
>> What's the state of the kernel
>> bits?  I would expect this through uq/master.
> 
> Kernel bits aren't merged yet. And the kernel headers will have to be
> updated in a previous step.
> 
> BTW, this series [1] would be nice to have. Dunno if there is a pull
> planned, but anyone trying to extend the KVM interface current runs
> against this.

Yeah, I was mostly waiting for acks/nacks. Since I didn't receive any, expect a 
pullreq next week.

Alex

> 
> Jan
> 
> [1] http://thread.gmane.org/gmane.comp.emulators.qemu/132962
>