Re: [Xen-devel] [PATCH v2 4/6] arm: add a function to invoke the PSCI handler

[Andre Przywara <andre.przywara@xxxxxxxxxx>]

On 12/02/2013 04:07 PM, Ian Campbell wrote:
> On Mon, 2013-12-02 at 12:08 +0100, Andre Przywara wrote:
> > The PSCI handler is invoked via a secure monitor call with the
> > arguments defined in registers. Copy the function from the
> > Linux code and adjust it to work on both ARM32 and ARM64.
> >
> > Signed-off-by: Andre Przywara <andre.przywara@xxxxxxxxxx>
> > ---
> >   xen/arch/arm/psci.c        | 28 ++++++++++++++++++++++++++++
> >   xen/include/asm-arm/psci.h |  1 +
> >   2 files changed, 29 insertions(+)
> >
> > diff --git a/xen/arch/arm/psci.c b/xen/arch/arm/psci.c
> > index 9ff06cd..cc382be 100644
> > --- a/xen/arch/arm/psci.c
> > +++ b/xen/arch/arm/psci.c
> > @@ -25,8 +25,36 @@
> >
> >   int psci_available;
> >
> > +#ifdef CONFIG_ARM_32
> > +#define REG_PREFIX "r"
> > +#else
> > +#define REG_PREFIX "x"
> > +#endif
> > +
> > +static noinline int __invoke_psci_fn_smc(u32 function_id, u32 arg0, u32 arg1,
> > +                                         u32 arg2)
> I should reread the PSCI spec, but are these not 64-bit on AArch64?
Indeed. Not for all functions and parameters, but for the start address 
at least that makes sense ;-)
Is there a type in Xen which reliably holds a native word? ulong or 
something?
Thanks,
Andre.


> > +{
> > +    asm volatile(
> > +        __asmeq("%0", REG_PREFIX"0")
> > +        __asmeq("%1", REG_PREFIX"1")
> > +        __asmeq("%2", REG_PREFIX"2")
> > +        __asmeq("%3", REG_PREFIX"3")
> > +        "smc #0"
> > +        : "+r" (function_id)
> > +        : "r" (arg0), "r" (arg1), "r" (arg2));
> > +
> > +    return function_id;
> > +}
> > +
> > +#undef REG_PREFIX
> > +
> >   static uint32_t psci_cpu_on_nr;
> >
> > +int call_psci_cpu_on(int cpu, void *smp_pen)
> > +{
> > +    return __invoke_psci_fn_smc(psci_cpu_on_nr, cpu, __pa(smp_pen), 0);
> > +}
> > +
> >   int __init psci_init(void)
> >   {
> >       struct dt_device_node *psci;
> > diff --git a/xen/include/asm-arm/psci.h b/xen/include/asm-arm/psci.h
> > index 2f37612..50513bf 100644
> > --- a/xen/include/asm-arm/psci.h
> > +++ b/xen/include/asm-arm/psci.h
> > @@ -10,6 +10,7 @@
> >   extern int psci_available;
> >
> >   int psci_init(void);
> > +int call_psci_cpu_on(int cpu, void *smp_pen);
> >
> >   /* functions to handle guest PSCI requests */
> >   int do_psci_cpu_on(uint32_t vcpuid, register_t entry_point);

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