linux-kernel - Re: [PATCH v7 05/12] arm64/boot: Factor out a macro to check SPE version

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Message-ID: <20250901100558.GJ745921@e132581.arm.com>
Date: Mon, 1 Sep 2025 11:05:58 +0100
From: Leo Yan <leo.yan@....com>
To: James Clark <james.clark@...aro.org>
Cc: Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>, Mark Rutland <mark.rutland@....com>,
	Jonathan Corbet <corbet@....net>, Marc Zyngier <maz@...nel.org>,
	Oliver Upton <oliver.upton@...ux.dev>,
	Joey Gouly <joey.gouly@....com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Zenghui Yu <yuzenghui@...wei.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Anshuman Khandual <anshuman.khandual@....com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org, linux-doc@...r.kernel.org,
	kvmarm@...ts.linux.dev
Subject: Re: [PATCH v7 05/12] arm64/boot: Factor out a macro to check SPE
 version

On Thu, Aug 14, 2025 at 10:25:27AM +0100, James Clark wrote:
> We check the version of SPE twice, and we'll add one more check in the
> next commit so factor out a macro to do this. Change the #3 magic number
> to the actual SPE version define (V1p2) to make it more readable.
> 
> No functional changes intended.
> 
> Tested-by: Leo Yan <leo.yan@....com>
> Signed-off-by: James Clark <james.clark@...aro.org>
> ---
>  arch/arm64/include/asm/el2_setup.h | 17 +++++++++++------
>  1 file changed, 11 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/el2_setup.h b/arch/arm64/include/asm/el2_setup.h
> index 46033027510c..3a4ca7f9acfb 100644
> --- a/arch/arm64/include/asm/el2_setup.h
> +++ b/arch/arm64/include/asm/el2_setup.h
> @@ -103,8 +103,7 @@
>  	csel	x2, xzr, x0, eq			// all PMU counters from EL1
>  
>  	/* Statistical profiling */
> -	ubfx	x0, x1, #ID_AA64DFR0_EL1_PMSVer_SHIFT, #4
> -	cbz	x0, .Lskip_spe_\@		// Skip if SPE not present
> +	__spe_vers_imp .Lskip_spe_\@, ID_AA64DFR0_EL1_PMSVer_IMP, x0 // Skip if SPE not present
>  
>  	mrs_s	x0, SYS_PMBIDR_EL1              // If SPE available at EL2,
>  	and	x0, x0, #(1 << PMBIDR_EL1_P_SHIFT)
> @@ -255,6 +254,14 @@
>  .Lskip_brbe_\@:
>  .endm
>  
> +/* Branch to skip_label if SPE version is less than given version */
> +.macro __spe_vers_imp skip_label, version, tmp
> +    mrs    \tmp, id_aa64dfr0_el1
> +    ubfx   \tmp, \tmp, #ID_AA64DFR0_EL1_PMSVer_SHIFT, #4
> +    cmp    \tmp, \version
> +    b.lt   \skip_label
> +.endm
> +

Just wondering if we need to move the macro to the beginning of the
file, so that we can define it first and call it afterwards.

Otherwise, LGTM:

Reviewed-by: Leo Yan <leo.yan@....com>

>  /* Disable any fine grained traps */
>  .macro __init_el2_fgt
>  	mrs	x1, id_aa64mmfr0_el1
> @@ -263,10 +270,8 @@
>  
>  	mov	x0, xzr
>  	mov	x2, xzr
> -	mrs	x1, id_aa64dfr0_el1
> -	ubfx	x1, x1, #ID_AA64DFR0_EL1_PMSVer_SHIFT, #4
> -	cmp	x1, #3
> -	b.lt	.Lskip_spe_fgt_\@
> +	/* If SPEv1p2 is implemented, */
> +	__spe_vers_imp .Lskip_spe_fgt_\@, #ID_AA64DFR0_EL1_PMSVer_V1P2, x1
>  	/* Disable PMSNEVFR_EL1 read and write traps */
>  	orr	x0, x0, #HDFGRTR_EL2_nPMSNEVFR_EL1_MASK
>  	orr	x2, x2, #HDFGWTR_EL2_nPMSNEVFR_EL1_MASK
> 
> -- 
> 2.34.1
>