Re: [PATCH] powerpc/numa: Fix topology_physical_package_id() on pSeries

From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: G@linux.vnet.ibm.com
Cc: Nathan Lynch <nathanl@linux.ibm.com>,
	Daniel Henrique Barboza <danielhb413@gmail.com>,
	Greg Kurz <groug@kaod.org>,
	Vasant Hegde <hegdevasant@linux.vnet.ibm.com>,
	linuxppc-dev@lists.ozlabs.org,
	David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [PATCH] powerpc/numa: Fix topology_physical_package_id() on pSeries
Date: Tue, 16 Mar 2021 10:53:40 +0530	[thread overview]
Message-ID: <20210316052340.GA2337468@linux.vnet.ibm.com> (raw)
In-Reply-To: <20210312143154.3181109-1-clg@kaod.org>

* C?dric Le Goater <clg@kaod.org> [2021-03-12 15:31:54]:

> Initial commit 15863ff3b8da ("powerpc: Make chip-id information
> available to userspace") introduce a cpu_to_chip_id() routine for the
> PowerNV platform using the "ibm,chip-id" property to query the chip id
> of a CPU. But PAPR does not specify such a property and the node id
> query is broken.
> 
> Use cpu_to_node() instead which guarantees to have a correct value on
> all platforms, PowerNV an pSeries.
> 

While this looks good to me, @mpe had reservations on using nid as chip-id.
https://lore.kernel.org/linuxppc-dev/87lfwhypv0.fsf@concordia.ellerman.id.au/t/#u
He may be okay with using nid as a "virtual" package id in a pseries
environment.

Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

> Cc: Nathan Lynch <nathanl@linux.ibm.com>
> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> Cc: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> ---
>  arch/powerpc/include/asm/topology.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h
> index 3beeb030cd78..887c42a4e43d 100644
> --- a/arch/powerpc/include/asm/topology.h
> +++ b/arch/powerpc/include/asm/topology.h
> @@ -123,7 +123,7 @@ static inline int cpu_to_coregroup_id(int cpu)
>  #ifdef CONFIG_PPC64
>  #include <asm/smp.h>
>  
> -#define topology_physical_package_id(cpu)	(cpu_to_chip_id(cpu))
> +#define topology_physical_package_id(cpu)	(cpu_to_node(cpu))
>  
>  #define topology_sibling_cpumask(cpu)	(per_cpu(cpu_sibling_map, cpu))
>  #define topology_core_cpumask(cpu)	(cpu_cpu_mask(cpu))
> -- 
> 2.26.2
> 

-- 
Thanks and Regards
Srikar Dronamraju