Re: [PATCH v7 06/22] RISC-V: Add Smcntrpmf extension parsing

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] Missing architectural dependency validation for `Smcntrpmf` requiring `Sscofpmf`.
- [Low] The commit message contains a confusing, grammatically incorrect sentence that obscures the technical meaning.
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commit f81e6e1ce235d73d77e6f5d1061ddb41f7aab7b6
Author: Atish Patra <atishp@rivosinc.com>

RISC-V: Add Smcntrpmf extension parsing

This commit adds parsing for the Smcntrpmf extension, allowing the kernel
to detect its presence. The extension enables M-mode to configure privilege
mode filtering for cycle/instret counters.

> Smcntrpmf extension allows M-mode to enable privilege mode filtering
> for cycle/instret counters. However, the cyclecfg/instretcfg CSRs are
> only available only in Ssccfg only Smcntrpmf is present.

[Severity: Low]
This isn't a bug, but there is a typo in the commit message where the word
"only" is repeated three times. Did you mean to say "... are available in
Ssccfg only if Smcntrpmf is present"?

> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 3fa0a563fb214..1452521d740a6 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
[ ... ]
> @@ -576,6 +576,7 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
>  	__RISCV_ISA_EXT_BUNDLE_VALIDATE(zvksg, riscv_zvksg_bundled_exts, riscv_ext_vector_crypto_validate),
>  	__RISCV_ISA_EXT_DATA_VALIDATE(zvkt, RISCV_ISA_EXT_ZVKT, riscv_ext_vector_crypto_validate),
>  	__RISCV_ISA_EXT_DATA(smaia, RISCV_ISA_EXT_SMAIA),
> +	__RISCV_ISA_EXT_DATA(smcntrpmf, RISCV_ISA_EXT_SMCNTRPMF),

[Severity: Medium]
Does this extension need a validation callback to enforce its dependency
on Sscofpmf?

According to the RISC-V specification, the Smcntrpmf extension explicitly
depends on the Sscofpmf extension. Using __RISCV_ISA_EXT_DATA instead of
__RISCV_ISA_EXT_DATA_VALIDATE omits these dependency checks.

A malformed device tree claiming smcntrpmf support without the requisite
Sscofpmf infrastructure might bypass validation and lead to an inconsistent
PMU driver state.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260622-counter_delegation-v7-0-0ba2fd34614e@meta.com?part=6