linux-kernel - Re: [PATCH 06/14] arm64: ssbd: Add global mitigation state accessor

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Date:   Wed, 23 May 2018 11:11:02 +0100
From:   Julien Grall <julien.grall@....com>
To:     Marc Zyngier <marc.zyngier@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kvmarm@...ts.cs.columbia.edu
Cc:     Kees Cook <keescook@...omium.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Andy Lutomirski <luto@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 06/14] arm64: ssbd: Add global mitigation state accessor

Hi Marc,

On 05/22/2018 04:06 PM, Marc Zyngier wrote:
> We're about to need the mitigation state in various parts of the
> kernel in order to do the right thing for userspace and guests.
> 
> Let's expose an accessor that will let other subsystems know
> about the state.
> 
> Signed-off-by: Marc Zyngier <marc.zyngier@....com>

Reviewed-by: Julien Grall <julien.grall@....com>

Cheers,

> ---
>   arch/arm64/include/asm/cpufeature.h | 10 ++++++++++
>   1 file changed, 10 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
> index 9bc548e22784..1bacdf57f0af 100644
> --- a/arch/arm64/include/asm/cpufeature.h
> +++ b/arch/arm64/include/asm/cpufeature.h
> @@ -543,6 +543,16 @@ static inline u64 read_zcr_features(void)
>   #define ARM64_SSBD_FORCE_ENABLE		2
>   #define ARM64_SSBD_MITIGATED		3
>   
> +static inline int arm64_get_ssbd_state(void)
> +{
> +#ifdef CONFIG_ARM64_SSBD
> +	extern int ssbd_state;
> +	return ssbd_state;
> +#else
> +	return ARM64_SSBD_UNKNOWN;
> +#endif
> +}
> +
>   #endif /* __ASSEMBLY__ */
>   
>   #endif
> 

-- 
Julien Grall