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

Feng Tang
2023-02-07T03:47:04Z

On Mon, Feb 06, 2023 at 08:18:32AM -0600, Terry Bowman wrote:
> From: "Borislav Petkov (AMD)" <bp@alien8.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@alien8.de>
> Signed-off-by: Terry Bowman <terry.bowman@amd.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
>