Re: [PATCH v5 1/2] perf/x86/amd/uncore: Add Hygon uncore PMU support

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Removal of Hygon L3 Uncore PMU support without a replacement in the new driver.
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--- Patch [1]: [PATCH v5 1/2] perf/x86/amd/uncore: Add Hygon uncore PMU support ---
commit 1b6dd18387bea20f9f548951bf79cae006705b47
Author: Qi Liu <[email protected]>

perf/x86/amd/uncore: Add Hygon uncore PMU support

This commit introduces a separate uncore PMU driver for Hygon processors to
support Data Fabric (DF) and Data Fabric IO Die (DF_IOD) counters. It also
removes the Hygon vendor checks from the AMD uncore driver to keep the
vendor-specific features separated.

> diff --git a/arch/x86/events/amd/hygon_uncore.c b/arch/x86/events/amd/hygon_uncore.c
> new file mode 100644
> index 0000000000000..471955d6fc282
> --- /dev/null
> +++ b/arch/x86/events/amd/hygon_uncore.c

[ ... ]

> +static struct hygon_uncore uncores[HYGON_UNCORE_TYPE_MAX] = {
> +	/* HYGON DF */
> +	{
> +		.scan = hygon_uncore_df_ctx_scan,
> +		.init = hygon_uncore_df_ctx_init,
> +		.move = hygon_uncore_ctx_move,
> +		.free = hygon_uncore_ctx_free,
> +	},
> +	/* HYGON DF IOD */
> +	{
> +		.scan = hygon_uncore_df_iod_ctx_scan,
> +		.init = hygon_uncore_df_iod_ctx_init,
> +		.move = hygon_uncore_ctx_move,
> +		.free = hygon_uncore_ctx_free,
> +	}
> +};

[ ... ]

> diff --git a/arch/x86/events/amd/uncore.c b/arch/x86/events/amd/uncore.c
> index dbc00b6dd69ee..6c486e1ab001a 100644
> --- a/arch/x86/events/amd/uncore.c
> +++ b/arch/x86/events/amd/uncore.c

[ ... ]

> @@ -1120,8 +1116,7 @@ static int __init amd_uncore_init(void)
>  	int ret = -ENODEV;
>  	int i;
>  
> -	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
> -	    boot_cpu_data.x86_vendor != X86_VENDOR_HYGON)
> +	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
>  		return -ENODEV;
>  
>  	if (!boot_cpu_has(X86_FEATURE_TOPOEXT))

[Severity: Medium]
Does this inadvertently remove L3 uncore PMU support for Hygon systems?

Removing the Hygon vendor check in amd_uncore_init() prevents the AMD uncore
driver from initializing on Hygon CPUs, which previously provided L3 cache PMU
support.

Looking at the new driver in hygon_uncore.c, the uncores[] array only
implements the DF and DF_IOD components. It does not appear to provide a
replacement for the L3 cache PMU that was previously available.

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Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=1