linux-kernel - Re: [PATCH 3/3] tools/x86/kcpuid: Dump the CPUID function in detailed view

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Message-ID: <Y+HIkTzNh4SXgVEc@feng-clx>
Date:   Tue, 7 Feb 2023 11:42:09 +0800
From:   Feng Tang <feng.tang@...el.com>
To:     Terry Bowman <terry.bowman@....com>
CC:     <linux-kernel@...r.kernel.org>, <bp@...e.de>, <x86@...nel.org>
Subject: Re: [PATCH 3/3] tools/x86/kcpuid: Dump the CPUID function in
 detailed view

On Mon, Feb 06, 2023 at 08:18:32AM -0600, Terry Bowman wrote:
> From: "Borislav Petkov (AMD)" <bp@...en8.de>
> 
> Sometimes it is useful to know which CPUID leaf contains the fields so
> add it to -d output so that it looks like this:
> 
>   CPUID_0x8000001e_ECX[0x0]:
>            extended_apic_id       : 0x8           - Extended APIC ID
>            core_id                : 0x4           - Identifies the logical core ID
>            threads_per_core       : 0x1           - The number of threads per core is threads_per_core + 1
>            node_id                : 0x0           - Node ID
>            nodes_per_processor    : 0x0           - Nodes per processor { 0: 1 node, else reserved }
> 
>   CPUID_0x8000001f_ECX[0x0]:
>            sme                 -  Secure Memory Encryption

The idea looks good to me, as providing clear info.

I gave it a run on my box, and there are some item with no valid bits
definition, like:

"
CPUID_0xd_ECX[0x2]:

CPUID_0xd_ECX[0x5]:

CPUID_0xd_ECX[0x6]:

CPUID_0xd_ECX[0x7]:

CPUID_0xd_ECX[0x8]:
"

Maybe we can check the sum of subleaf->info.nr[EAX/EBX/ECX/EDX],
and only print it out when it is not zero.

Thanks,
Feng

> 
> ...
> 
> Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
> Signed-off-by: Terry Bowman <terry.bowman@....com>
> ---
>  tools/arch/x86/kcpuid/kcpuid.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/arch/x86/kcpuid/kcpuid.c b/tools/arch/x86/kcpuid/kcpuid.c
> index dae75511fef7..3bab3398cec3 100644
> --- a/tools/arch/x86/kcpuid/kcpuid.c
> +++ b/tools/arch/x86/kcpuid/kcpuid.c
> @@ -468,13 +468,21 @@ static void show_leaf(struct subleaf *leaf)
>  	if (!leaf)
>  		return;
>  
> -	if (show_raw)
> +	if (show_raw) {
>  		leaf_print_raw(leaf);
> +	} else {
> +		if (show_details)
> +			printf("CPUID_0x%x_ECX[0x%x]:\n",
> +				leaf->index, leaf->sub);
> +	}
>  
>  	decode_bits(leaf->eax, &leaf->info[R_EAX]);
>  	decode_bits(leaf->ebx, &leaf->info[R_EBX]);
>  	decode_bits(leaf->ecx, &leaf->info[R_ECX]);
>  	decode_bits(leaf->edx, &leaf->info[R_EDX]);
> +
> +	if (!show_raw && show_details)
> +		printf("\n");
>  }
>  
>  static void show_func(struct cpuid_func *func)
> -- 
> 2.34.1
>