linux-kernel - Re: [PATCH PATCH v2 1/9] x86/cpu/topology: Add CPU type to struct cpuinfo

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Date: Fri, 28 Jun 2024 10:03:05 +0200
From: Borislav Petkov <bp@...en8.de>
To: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
	daniel.sneddon@...ux.intel.com, tony.luck@...el.com,
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	linux-perf-users@...r.kernel.org,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	Andrew Cooper <andrew.cooper3@...rix.com>,
	Brice Goglin <brice.goglin@...il.com>,
	Mario Limonciello <mario.limonciello@....com>,
	Perry Yuan <Perry.Yuan@....com>,
	Dapeng Mi <dapeng1.mi@...ux.intel.com>
Subject: Re: [PATCH PATCH v2 1/9] x86/cpu/topology: Add CPU type to struct
 cpuinfo_topology

On Thu, Jun 27, 2024 at 01:44:06PM -0700, Pawan Gupta wrote:
> The hw_cpu_type is populated in the below debugfs file:
> 
>   # cat /sys/kernel/debug/x86/topo/cpus/#

What "below debugfs file"? A '#'?

> diff --git a/arch/x86/kernel/cpu/debugfs.c b/arch/x86/kernel/cpu/debugfs.c
> index 3baf3e435834..8082e03a5976 100644
> --- a/arch/x86/kernel/cpu/debugfs.c
> +++ b/arch/x86/kernel/cpu/debugfs.c
> @@ -22,6 +22,7 @@ static int cpu_debug_show(struct seq_file *m, void *p)
>  	seq_printf(m, "die_id:              %u\n", c->topo.die_id);
>  	seq_printf(m, "cu_id:               %u\n", c->topo.cu_id);
>  	seq_printf(m, "core_id:             %u\n", c->topo.core_id);
> +	seq_printf(m, "hw_cpu_type:         %x\n", c->topo.hw_cpu_type);

Yeah, no, we're not going to perpetuate this silliness of printing hex
values without a preceding "0x".

>  	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, "llc_id:              %u\n", c->topo.llc_id);
> diff --git a/arch/x86/kernel/cpu/topology_common.c b/arch/x86/kernel/cpu/topology_common.c
> index 9a6069e7133c..8b47bd6b0623 100644
> --- a/arch/x86/kernel/cpu/topology_common.c
> +++ b/arch/x86/kernel/cpu/topology_common.c
> @@ -140,6 +140,14 @@ static void parse_topology(struct topo_scan *tscan, bool early)
>  	}
>  }
>  
> +static void topo_set_hw_cpu_type(struct cpuinfo_x86 *c)
> +{
> +	c->topo.hw_cpu_type = X86_HW_CPU_TYPE_UNKNOWN;
> +
> +	if (c->x86_vendor == X86_VENDOR_INTEL && c->cpuid_level >= 0x1a)
> +		c->topo.hw_cpu_type = cpuid_eax(0x1a) >> X86_CPU_TYPE_INTEL_SHIFT;
> +}

Why isn't this happening in cpu/intel.c? And then you don't need yet
another silly function.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette