linux-kernel - Re: [PATCH v4 09/21] RISC-V: Add Ssccfg ISA extension definition and parsing

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Message-ID: <d03581a9-495d-47df-99f2-96065b06ee8f@rivosinc.com>
Date: Fri, 7 Feb 2025 09:13:56 +0100
From: Clément Léger <cleger@...osinc.com>
To: Atish Patra <atishp@...osinc.com>,
 Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt
 <palmer@...belt.com>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Anup Patel <anup@...infault.org>,
 Atish Patra <atishp@...shpatra.org>, Will Deacon <will@...nel.org>,
 Mark Rutland <mark.rutland@....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>, weilin.wang@...el.com
Cc: linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
 Conor Dooley <conor@...nel.org>, devicetree@...r.kernel.org,
 kvm@...r.kernel.org, kvm-riscv@...ts.infradead.org,
 linux-arm-kernel@...ts.infradead.org, linux-perf-users@...r.kernel.org
Subject: Re: [PATCH v4 09/21] RISC-V: Add Ssccfg ISA extension definition and
 parsing



On 06/02/2025 08:23, Atish Patra wrote:
> Ssccfg (‘Ss’ for Privileged architecture and Supervisor-level
> extension, ‘ccfg’ for Counter Configuration) provides access to
> delegated counters and new supervisor-level state.
> 
> This patch just enables the definitions and enable parsing.
> 
> Signed-off-by: Atish Patra <atishp@...osinc.com>
> ---
>  arch/riscv/include/asm/hwcap.h | 2 ++
>  arch/riscv/kernel/cpufeature.c | 2 ++
>  2 files changed, 4 insertions(+)
> 
> diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
> index b4eddcb57842..fa5e01bcb990 100644
> --- a/arch/riscv/include/asm/hwcap.h
> +++ b/arch/riscv/include/asm/hwcap.h
> @@ -103,6 +103,8 @@
>  #define RISCV_ISA_EXT_SSCSRIND		94
>  #define RISCV_ISA_EXT_SMCSRIND		95
>  #define RISCV_ISA_EXT_SMCNTRPMF         96
> +#define RISCV_ISA_EXT_SSCCFG            97
> +#define RISCV_ISA_EXT_SMCDELEG          98
>  
>  #define RISCV_ISA_EXT_XLINUXENVCFG	127
>  
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 8f225c9c3055..3cb208d4913e 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -390,12 +390,14 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
>  	__RISCV_ISA_EXT_BUNDLE(zvksg, riscv_zvksg_bundled_exts),
>  	__RISCV_ISA_EXT_DATA(zvkt, RISCV_ISA_EXT_ZVKT),
>  	__RISCV_ISA_EXT_DATA(smaia, RISCV_ISA_EXT_SMAIA),
> +	__RISCV_ISA_EXT_DATA(smcdeleg, RISCV_ISA_EXT_SMCDELEG),

Hi Atish,

based on your dt-binding commit, if smcdeleg depends on Sscsrind, Zihpm,
Zicntr, then you could add a validation callback here:

static int riscv_smcdeleg_validate(const struct riscv_isa_ext_data
*data, const unsigned long *isa_bitmap)
{
	if (__riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_SSCSRIND) &&
	    __riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_ZIHPM) &&
	    __riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_ZICNTR))
		return 0;

	return -EPROBE_DEFER;
}

__RISCV_ISA_EXT_DATA_VALIDATE(smcdeleg, RISCV_ISA_EXT_SMCDELEG,
riscv_smcdeleg_validate),

>  	__RISCV_ISA_EXT_DATA(smcntrpmf, RISCV_ISA_EXT_SMCNTRPMF),
>  	__RISCV_ISA_EXT_DATA(smcsrind, RISCV_ISA_EXT_SMCSRIND),
>  	__RISCV_ISA_EXT_DATA(smmpm, RISCV_ISA_EXT_SMMPM),
>  	__RISCV_ISA_EXT_SUPERSET(smnpm, RISCV_ISA_EXT_SMNPM, riscv_xlinuxenvcfg_exts),
>  	__RISCV_ISA_EXT_DATA(smstateen, RISCV_ISA_EXT_SMSTATEEN),
>  	__RISCV_ISA_EXT_DATA(ssaia, RISCV_ISA_EXT_SSAIA),
> +	__RISCV_ISA_EXT_DATA(ssccfg, RISCV_ISA_EXT_SSCCFG),

Ditto for this one with Smcdeleg, Sscsrind, Zihpm, Zicntr, Sscofpmf,
Smcntrpmf.

Thanks,

Clément

>  	__RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),
>  	__RISCV_ISA_EXT_DATA(sscsrind, RISCV_ISA_EXT_SSCSRIND),
>  	__RISCV_ISA_EXT_SUPERSET(ssnpm, RISCV_ISA_EXT_SSNPM, riscv_xlinuxenvcfg_exts),
>