linux-kernel - Re: [PATCH 6/8] arm64: cpufeature: Relax AArch32 system checks if EL1 is 64-bit only

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Date:   Wed, 15 Apr 2020 11:43:36 +0100
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     will@...nel.org, linux-arm-kernel@...ts.infradead.org,
        kvmarm@...ts.cs.columbia.edu
Cc:     linux-kernel@...r.kernel.org, mark.rutland@....com, maz@...nel.org,
        anshuman.khandual@....com, catalin.marinas@....com,
        saiprakash.ranjan@...eaurora.org, dianders@...omium.org,
        kernel-team@...roid.com
Subject: Re: [PATCH 6/8] arm64: cpufeature: Relax AArch32 system checks if EL1
 is 64-bit only

On 04/14/2020 10:31 PM, Will Deacon wrote:
> If AArch32 is not supported at EL1, the AArch32 feature register fields
> no longer advertise support for some system features:
> 
>    * ISAR4.SMC
>    * PFR1.{Virt_frac, Sec_frac, Virtualization, Security, ProgMod}
> 
> In which case, we don't need to emit "SANITY CHECK" failures for all of
> them.
> 
> Add logic to relax the strictness of individual feature register fields
> at runtime and use this for the fields above if 32-bit EL1 is not
> supported.
> 
> Signed-off-by: Will Deacon <will@...nel.org>

Reviewed-by: Suzuki K Poulose <suzuki.poulose@....com>