[PATCHv2 02/12] arm64: smp_plat: add get_logical_index

[catalin.marinas@arm.com (Catalin Marinas)]

On Mon, May 18, 2015 at 06:55:32PM +0100, Mark Rutland wrote:
> On Mon, May 18, 2015 at 06:09:13PM +0100, Catalin Marinas wrote:
> > On Mon, May 18, 2015 at 11:38:13AM +0100, Mark Rutland wrote:
> > > The PSCI MIGRATE_INFO_UP_CPU call returns a physical ID, which we will
> > > need to map back to a Linux logical ID.
> > > 
> > > Implement a reusable get_logical_index to map from a physical ID to a
> > > logical ID.
> > > 
> > > Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> > > Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> > > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > > Cc: Will Deacon <will.deacon@arm.com>
> > > ---
> > >  arch/arm64/include/asm/smp_plat.h | 16 ++++++++++++++++
> > >  1 file changed, 16 insertions(+)
> > > 
> > > diff --git a/arch/arm64/include/asm/smp_plat.h b/arch/arm64/include/asm/smp_plat.h
> > > index 8dcd61e..7abf757 100644
> > > --- a/arch/arm64/include/asm/smp_plat.h
> > > +++ b/arch/arm64/include/asm/smp_plat.h
> > > @@ -19,6 +19,8 @@
> > >  #ifndef __ASM_SMP_PLAT_H
> > >  #define __ASM_SMP_PLAT_H
> > >  
> > > +#include <linux/cpumask.h>
> > > +
> > >  #include <asm/types.h>
> > >  
> > >  struct mpidr_hash {
> > > @@ -39,6 +41,20 @@ static inline u32 mpidr_hash_size(void)
> > >   */
> > >  extern u64 __cpu_logical_map[NR_CPUS];
> > >  #define cpu_logical_map(cpu)    __cpu_logical_map[cpu]
> > > +/*
> > > + * Retrieve logical cpu index corresponding to a given MPIDR.Aff*
> > > + *  - mpidr: MPIDR.Aff* bits to be used for the look-up
> > > + *
> > > + * Returns the cpu logical index or -EINVAL on look-up error
> > > + */
> > > +static inline int get_logical_index(u64 mpidr)
> > > +{
> > > +	int cpu;
> > > +	for (cpu = 0; cpu < nr_cpu_ids; cpu++)
> > > +		if (cpu_logical_map(cpu) == mpidr)
> > > +			return cpu;
> > > +	return -EINVAL;
> > > +}
> > 
> > Do we guarantee that mpidr here only contains the affinity bits (i.e. no
> > masking)?
> 
> In the DT and ACPI probe paths we reject IDs with bits other than the
> aff bits set.
> 
> I don't currently have a sanity check in the code handling
> MIGRATE_INFO_UP_CPU, but I should add one.
> 
> Would you like a warning here too?

Or maybe just the warning if the code paths to this function already
mask out the non-affinity bits.

-- 
Catalin