linux-kernel - Re: [PATCH v5 05/16] x86/pmu: enable Hygon support to PMU infrastructure

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Date:   Tue, 4 Sep 2018 12:48:12 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Pu Wen <puwen@...on.cn>
Cc:     tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        x86@...nel.org, thomas.lendacky@....com, pbonzini@...hat.com,
        linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org
Subject: Re: [PATCH v5 05/16] x86/pmu: enable Hygon support to PMU
 infrastructure

On Wed, Aug 29, 2018 at 08:43:54PM +0800, Pu Wen wrote:
> Hygon PMU arch is similar to AMD Family 17h. To support Hygon PMU, the
> initialization flow for it just call amd_pmu_init() and change PMU name

That sentence reads funny.

> to "HYGON". To share AMD's flow, add code check for Hygon family ID 18h

s/family ID/family/

> to run the code path of AMD family 17h in core/uncore functions.
> 
> Also it returns the bit offset of the performance counter register and
> event selection register for Hygon CPU in the similar way as AMD does.

In general, you seem to be explaining *what* your patches do and not
*why*. This is the wrong. Always explain the *why* - the *what* is
visible from the diff.

You probably need to brush up on
Documentation/process/submitting-patches.rst, section 2.

> Signed-off-by: Pu Wen <puwen@...on.cn>
> ---
>  arch/x86/events/amd/core.c             |  6 ++++++
>  arch/x86/events/amd/uncore.c           | 15 ++++++++++-----
>  arch/x86/events/core.c                 |  4 ++++
>  arch/x86/kernel/cpu/perfctr-watchdog.c |  2 ++
>  4 files changed, 22 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
> index c84584b..6c13c9d 100644
> --- a/arch/x86/events/amd/core.c
> +++ b/arch/x86/events/amd/core.c
> @@ -669,6 +669,12 @@ static int __init amd_core_pmu_init(void)
>  		 * We fallback to using default amd_get_event_constraints.
>  		 */
>  		break;
> +	case 0x18:
> +		if (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
> +			pr_cont("Fam18h ");

Didn't we agree that you'll verify whether family 0x18 is going to be
Hygon only?

What happened to that checking?

> +			/* Using default amd_get_event_constraints. */
> +			break;
> +		}
>  	default:
>  		pr_err("core perfctr but no constraints; unknown hardware!\n");
>  		return -ENODEV;
> diff --git a/arch/x86/events/amd/uncore.c b/arch/x86/events/amd/uncore.c
> index 981ba5e..9f2eb43 100644
> --- a/arch/x86/events/amd/uncore.c
> +++ b/arch/x86/events/amd/uncore.c
> @@ -507,17 +507,22 @@ static int __init amd_uncore_init(void)
>  {
>  	int ret = -ENODEV;
>  
> -	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
> +	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
> +	    boot_cpu_data.x86_vendor != X86_VENDOR_HYGON)
>  		return -ENODEV;
>  
>  	if (!boot_cpu_has(X86_FEATURE_TOPOEXT))
>  		return -ENODEV;
>  
> -	if (boot_cpu_data.x86 == 0x17) {
> +	if ((boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
> +	     boot_cpu_data.x86 == 0x17) ||
> +	    (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON &&
> +	     boot_cpu_data.x86 == 0x18)) {

Same here.

What's up?

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.