Re: [PATCH v6 04/12] ARM: KVM: Hypervisor inititalization

Rusty Russell
2012-03-13T04:40:04Z

On Sun, 11 Mar 2012 18:24:03 -0400, Christoffer Dall <c.dall@virtualopensystems.com> wrote:
> On Thu, Feb 23, 2012 at 11:00 PM, Rusty Russell <rusty@rustcorp.com.au> wrote:
> > On Thu, 23 Feb 2012 02:32:39 -0500, Christoffer Dall <c.dall@virtualopensystems.com> wrote:
> >> +     /*
> >> +      * Allocate stack pages for Hypervisor-mode
> >> +      */
> >> +     for_each_possible_cpu(cpu)
> >> +             per_cpu(kvm_arm_hyp_stack_page, cpu) = NULL;
> >
> > This is weird; we can't call this init function multiple times without
> > reloading the module.
> >
>
> what you're saying is that static DEFINE_PER_CPU will still be
> initialized to zero? I don't actually have experience with this, but I
> assumed that the data..percpu section would not necessarily be zeroed
> out when loading a module... Now I tried to look, but I couldn't
> convince myself. Can you enlighten me?

Absolutely and definitely. It's placed in a special section, and from
there copied into the per-cpu sections by the module loader but still
follows the C semantics of being zero-initialized.

Cheers,
Rusty.
--
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