On Fri, 02 Dec 2011, Jan Kiszka wrote:
> 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@xxxxxxxxx>
> > Cc: Avi Kivity <avi@xxxxxxxxxx>
> > Cc: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
> > Cc: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
> > Cc: ryanh@xxxxxxxxxxxxxxxxxx
> > Cc: aliguori@xxxxxxxxxx
> > Cc: kvm@xxxxxxxxxxxxxxx
> >
> > ---
> > 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) {
>
Functionally equivalent and I see both in the code, is there a standard?
> > + 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.
>
Also following an example seen elsewhere.
> > + }
> > + }
> > +}
> > +
>
> Again: please use checkpatch.pl.
>
Sorry, tough to get used to hitting space bar that many times...
> > 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?
Because the new handler doesn't touch the KVMClockState object. If this is
preferred, I have no objection.
>
> 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.
The flag itself is stored in the pvclock_vcpu_time_info structure, and anything
else that touches that structure uses ioctls.
>
> Jan
>
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