On Mon, May 9, 2011 at 8:43 AM, Catalin Marinas <catalin.marinas at arm.com> wrote:
> On Mon, 2011-05-09 at 16:31 +0100, Hollis Blanchard wrote:
>> > +/*
>> > + * Change the current processor mode to Hyp mode.
>> > + * You should never return to user space or enable interrupts before calling
>> > + * kvm_arm_hyp_return.
>> > + */
>> > +static inline void kvm_arm_hyp_mode(void)
>> > +{
>> > + ? ? ? __asm__ (
>> > + ? ? ? ? ? ? ? "push ? {lr}\n\t"
>> > + ? ? ? ? ? ? ? "hvc ? ?#0\n\t"
>> > + ? ? ? ? ? ? ? "pop ? ?{lr}\n\t");
>> > +}
>> > +
>> > +/*
>> > + * Return from Hyp mode to Svc mode.
>> > + */
>> > +static inline void kvm_arm_hyp_return(void)
>> > +{
>> > + ? ? ? __asm__ (
>> > + ? ? ? ? ? ? ? "push ? {lr}\n\t"
>> > + ? ? ? ? ? ? ? "hvc ? ?#0\n\t"
>> > + ? ? ? ? ? ? ? "pop ? ?{lr}\n\t");
>> > +}
>>
>> Are these hypercalls that return in a new processor privilege level?
>> (Also, I don't see them being used anywhere.)
>
> The HVC makes the switch to the Hypervisor mode (similar to how SVC
> switches from User to Supervisor mode).
OK, so the push/pop is actually the parameter passing ABI. Fine.
>> Is the A15 ISA documentation available anywhere yet?
>
> The A15 consists of the standard ARMv7 ISA plus the virtualisation
> extensions. These are described in:
>
> http://infocenter.arm.com/help/topic/com.arm.doc.ddi0406b_virtualization_extns/index.html
Thanks.
-Hollis
