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Re: [Qemu-devel] [PATCH] Guest stop notification
From: |
Eric B Munson |
Subject: |
Re: [Qemu-devel] [PATCH] Guest stop notification |
Date: |
Thu, 1 Dec 2011 16:32:56 -0500 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Thu, 01 Dec 2011, Marcelo Tosatti wrote:
> On Thu, Dec 01, 2011 at 06:36:17PM +0100, Jan Kiszka wrote:
> > On 2011-12-01 18:22, Eric B Munson wrote:
> > > On Thu, 01 Dec 2011, Jan Kiszka wrote:
> > >
> > >> On 2011-11-29 22:36, 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 <address@hidden>
> > >>> Cc: address@hidden
> > >>> Cc: address@hidden
> > >>> Cc: address@hidden
> > >>> Cc: address@hidden
> > >>> Cc: address@hidden
> > >>> Cc: address@hidden
> > >>> ---
> > >>> target-i386/kvm.c | 6 ++++++
> > >>> 1 files changed, 6 insertions(+), 0 deletions(-)
> > >>>
> > >>> diff --git a/target-i386/kvm.c b/target-i386/kvm.c
> > >>> index 5bfc21f..defd364 100644
> > >>> --- a/target-i386/kvm.c
> > >>> +++ b/target-i386/kvm.c
> > >>> @@ -336,12 +336,18 @@ static int kvm_inject_mce_oldstyle(CPUState *env)
> > >>> return 0;
> > >>> }
> > >>>
> > >>> +static void kvm_put_guest_paused(CPUState *penv)
> > >>> +{
> > >>> + kvm_vcpu_ioctl(penv, KVM_GUEST_PAUSED, 0);
> > >>> +}
> > >>
> > >> I see no need in encapsulating this in a separate function.
> > >>
> > >>> +
> > >>> static void cpu_update_state(void *opaque, int running, RunState state)
> > >>> {
> > >>> CPUState *env = opaque;
> > >>>
> > >>> if (running) {
> > >>> env->tsc_valid = false;
> > >>> + kvm_put_guest_paused(env);
> > >>
> > >> checkpatch.pl would have asked you to remove this tab.
> > >>
> > >> More general:
> > >>
> > >> Why is this x86-only? If the kernel interface is x86-only, what prevents
> > >> making it generic right from the beginning?
> > >
> > > Sorry, missed this question on the first pass, this is x86 only because
> > > the
> > > flag used lives in the pvclock structure. AFAICT, there aren't any other
> > > architectures out there that implement paravirtualized clocks yet.
> >
> > That's an implementation "detail" of the kernel. The interface (IOCTL or
> > kvm_run field) is generic, no?
> >
> > I would just fire this notification from generic code, evaluate the
> > error (that was lacking so far), and only report it if it's something
> > else than "not supported".
>
> Yes, it should live in hw/kvmclock.c preferably.
>
Okay, I get a V3 with this moved around out tomorrow.
Thanks for the feedback,
Eric
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