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Subject: Re: [PATCH] riscv: don't warn for sifive erratas in modules
To:     Heiko Stuebner <heiko@sntech.de>, palmer@dabbelt.com,
        paul.walmsley@sifive.com
Cc:     linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        wefu@redhat.com, guoren@kernel.org, cmuellner@linux.com,
        philipp.tomsich@vrull.eu, hch@lst.de
References: <20220608120849.1695191-1-heiko@sntech.de>
From:   Ron Economos <re@w6rz.net>
In-Reply-To: <20220608120849.1695191-1-heiko@sntech.de>
Message-ID: <21e02dbd-75b0-e5c6-29d8-fc853c72aa01@w6rz.net>
Date:   Wed, 8 Jun 2022 21:05:33 -0700
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On 6/8/22 5:08 AM, Heiko Stuebner wrote:
> The SiFive errata code contains code checking applicable erratas
> vs. actually applied erratas to suggest missing erratas to the
> user when their Kconfig options are not enabled.
>
> In the main kernel image one can be quite sure that all available
> erratas appear at least once, so that check will succeed.
> On the other hand modules can very well not use any errata-relevant
> code, so the newly added module-alternative support may also patch
> the module code, but not touch SiFive-specific erratas at all.
>
> So to restore the original behaviour don't warn when patching
> modules. This will keep the warning if necessary for the main kernel
> image but prevent spurious warnings for modules.
>
> Of course having such a vendor-specific warning may not be needed at
> all, as CONFIG_ERRATA_SIFIVE is selected by CONFIG_SOC_SIFIVE and the
> individual erratas are default-y so disabling them requires
> deliberate action anyway. But for now just restore the old behaviour.
>
> Fixes: a8e910168bba ("riscv: implement module alternatives")
> Reported-by: Ron Economos <re@w6rz.net>
> Signed-off-by: Heiko Stuebner <heiko@sntech.de>
> ---
>   arch/riscv/errata/sifive/errata.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/riscv/errata/sifive/errata.c b/arch/riscv/errata/sifive/errata.c
> index 672f02b21ce0..1031038423e7 100644
> --- a/arch/riscv/errata/sifive/errata.c
> +++ b/arch/riscv/errata/sifive/errata.c
> @@ -111,6 +111,7 @@ void __init_or_module sifive_errata_patch_func(struct alt_entry *begin,
>   			cpu_apply_errata |= tmp;
>   		}
>   	}
> -	if (cpu_apply_errata != cpu_req_errata)
> +	if (stage != RISCV_ALTERNATIVES_MODULE &&
> +	    cpu_apply_errata != cpu_req_errata)
>   		warn_miss_errata(cpu_req_errata - cpu_apply_errata);
>   }

Tested on HiFive Unmatched. Works good and the spurious warning is 
suppressed.

Tested-by: Ron Economos <re@w6rz.net>