On Thu, May 13, 2010 at 03:57:05PM +0200, Jan Kiszka wrote:
> Gleb Natapov wrote:
> > When in-kernel irqchip is used env->halted is never used for anything
> > except "info cpus" command.
>
> In fact, it's used in a few more places, namely cpu_dump_state and the
> gdbstub.
>
Both of those places use env->halted the same way "info cpus" does:
print out cpu state. And the both call for cpu_synchronize_state()
before using env->halted.
> > Halted state is synced in
> > kvm_arch_save_mpstate() and showed by do_info_cpus() but otherwise never
> > looked at. Zeroing it here breaks "info cpus" since before
> > do_info_cpus() outputs env->halted in io thread it is zeroed here when
> > vcpu thread reenters kernel.
>
> Looks good for current qemu-kvm.
>
> Execution of kvm_cpu_exec once depended on env->halted, even for
> in-kernel irqchip, right?
Never in qemu-kvm AFAIR. May be at some point during merge between
upstream qemu and qemu-kvm such bug was introduced,
> Anyway, there are not such traces left here.
> We will just need to look at it again when pushing in-kernel irqchips
> upstream as its kvm loop looks different.
>
> Jan
>
> >
> > Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
> > diff --git a/qemu-kvm-x86.c b/qemu-kvm-x86.c
> > index 61d9331..0ec2881 100644
> > --- a/qemu-kvm-x86.c
> > +++ b/qemu-kvm-x86.c
> > @@ -922,10 +922,6 @@ void kvm_arch_load_regs(CPUState *env, int level)
> > if (env->kvm_vcpu_update_vapic)
> > kvm_tpr_enable_vapic(env);
> > }
> > - if (kvm_irqchip_in_kernel()) {
> > - /* Avoid deadlock: no user space IRQ will ever clear it. */
> > - env->halted = 0;
> > - }
> >
> > kvm_put_vcpu_events(env, level);
> > kvm_put_debugregs(env);
> > --
> > Gleb.
>
>
--
Gleb.
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