Re: [PATCH v6 02/10] x86/topology: Introduce topology_logical_core_id()

["Gautham R. Shenoy" <gautham.shenoy@amd.com>]

On Fri, Oct 25, 2024 at 11:13:40AM +0000, Dhananjay Ugwekar wrote:
> From: K Prateek Nayak <kprateek.nayak@amd.com>
> 
> On x86, topology_core_id() returns a unique core ID within the PKG
> domain. Looking at match_smt() suggests that a core ID just needs to be
> unique within a LLC domain. For use cases such as the core RAPL PMU,
> there exists a need for a unique core ID across the entire system with
> multiple PKG domains. Introduce topology_logical_core_id() to derive a
> unique core ID across the system.
> 
> Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
> Reviewed-by: Zhang Rui <rui.zhang@intel.com>
> Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> Signed-off-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@amd.com>

LGTM

Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>

--
Thanks and Regards
gautham.

> ---
>  Documentation/arch/x86/topology.rst   | 4 ++++
>  arch/x86/include/asm/processor.h      | 1 +
>  arch/x86/include/asm/topology.h       | 1 +
>  arch/x86/kernel/cpu/debugfs.c         | 1 +
>  arch/x86/kernel/cpu/topology_common.c | 1 +
>  5 files changed, 8 insertions(+)
> 
> diff --git a/Documentation/arch/x86/topology.rst b/Documentation/arch/x86/topology.rst
> index 7352ab89a55a..c12837e61bda 100644
> --- a/Documentation/arch/x86/topology.rst
> +++ b/Documentation/arch/x86/topology.rst
> @@ -135,6 +135,10 @@ Thread-related topology information in the kernel:
>      The ID of the core to which a thread belongs. It is also printed in /proc/cpuinfo
>      "core_id."
>  
> +  - topology_logical_core_id();
> +
> +    The logical core ID to which a thread belongs.
> +
>  
>  
>  System topology examples
> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
> index 4a686f0e5dbf..595859cbf7ff 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -98,6 +98,7 @@ struct cpuinfo_topology {
>  	// Logical ID mappings
>  	u32			logical_pkg_id;
>  	u32			logical_die_id;
> +	u32			logical_core_id;
>  
>  	// AMD Node ID and Nodes per Package info
>  	u32			amd_node_id;
> diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
> index aef70336d624..672fccf9f845 100644
> --- a/arch/x86/include/asm/topology.h
> +++ b/arch/x86/include/asm/topology.h
> @@ -137,6 +137,7 @@ extern const struct cpumask *cpu_clustergroup_mask(int cpu);
>  #define topology_logical_package_id(cpu)	(cpu_data(cpu).topo.logical_pkg_id)
>  #define topology_physical_package_id(cpu)	(cpu_data(cpu).topo.pkg_id)
>  #define topology_logical_die_id(cpu)		(cpu_data(cpu).topo.logical_die_id)
> +#define topology_logical_core_id(cpu)		(cpu_data(cpu).topo.logical_core_id)
>  #define topology_die_id(cpu)			(cpu_data(cpu).topo.die_id)
>  #define topology_core_id(cpu)			(cpu_data(cpu).topo.core_id)
>  #define topology_ppin(cpu)			(cpu_data(cpu).ppin)
> diff --git a/arch/x86/kernel/cpu/debugfs.c b/arch/x86/kernel/cpu/debugfs.c
> index 3baf3e435834..b1eb6d7828db 100644
> --- a/arch/x86/kernel/cpu/debugfs.c
> +++ b/arch/x86/kernel/cpu/debugfs.c
> @@ -24,6 +24,7 @@ static int cpu_debug_show(struct seq_file *m, void *p)
>  	seq_printf(m, "core_id:             %u\n", c->topo.core_id);
>  	seq_printf(m, "logical_pkg_id:      %u\n", c->topo.logical_pkg_id);
>  	seq_printf(m, "logical_die_id:      %u\n", c->topo.logical_die_id);
> +	seq_printf(m, "logical_core_id:     %u\n", c->topo.logical_core_id);
>  	seq_printf(m, "llc_id:              %u\n", c->topo.llc_id);
>  	seq_printf(m, "l2c_id:              %u\n", c->topo.l2c_id);
>  	seq_printf(m, "amd_node_id:         %u\n", c->topo.amd_node_id);
> diff --git a/arch/x86/kernel/cpu/topology_common.c b/arch/x86/kernel/cpu/topology_common.c
> index 9a6069e7133c..23722aa21e2f 100644
> --- a/arch/x86/kernel/cpu/topology_common.c
> +++ b/arch/x86/kernel/cpu/topology_common.c
> @@ -151,6 +151,7 @@ static void topo_set_ids(struct topo_scan *tscan, bool early)
>  	if (!early) {
>  		c->topo.logical_pkg_id = topology_get_logical_id(apicid, TOPO_PKG_DOMAIN);
>  		c->topo.logical_die_id = topology_get_logical_id(apicid, TOPO_DIE_DOMAIN);
> +		c->topo.logical_core_id = topology_get_logical_id(apicid, TOPO_CORE_DOMAIN);
>  	}
>  
>  	/* Package relative core ID */
> -- 
> 2.34.1
>