linux-kernel - Re: [PATCH 1/2] KVM: arm64: Replace custom macros with fields from ID_AA64PFR0

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Date: Thu, 18 Apr 2024 08:39:29 +0100
From: Marc Zyngier <maz@...nel.org>
To: Anshuman Khandual <anshuman.khandual@....com>
Cc: linux-arm-kernel@...ts.infradead.org,
	catalin.marinas@....com,
	Oliver Upton <oliver.upton@...ux.dev>,
	Will Deacon <will@...nel.org>,
	kvmarm@...ts.linux.dev,
	linux-kernel@...r.kernel.org, Fuad Tabba <tabba@...gle.com>
Subject: Re: [PATCH 1/2] KVM: arm64: Replace custom macros with fields from ID_AA64PFR0_EL1

+ Fuad

On Thu, 18 Apr 2024 06:38:03 +0100,
Anshuman Khandual <anshuman.khandual@....com> wrote:
> 
> This replaces custom macros usage (i.e ID_AA64PFR0_EL1_ELx_64BIT_ONLY and
> ID_AA64PFR0_EL1_ELx_32BIT_64BIT) and instead directly uses register fields
> from ID_AA64PFR0_EL1 sysreg definition.
> 
> Cc: Marc Zyngier <maz@...nel.org>
> Cc: Oliver Upton <oliver.upton@...ux.dev>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Will Deacon <will@...nel.org>
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: kvmarm@...ts.linux.dev
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
> ---
>  arch/arm64/kvm/hyp/include/nvhe/fixed_config.h | 8 ++++----
>  arch/arm64/kvm/hyp/nvhe/pkvm.c                 | 4 ++--
>  arch/arm64/kvm/hyp/nvhe/sys_regs.c             | 2 +-
>  3 files changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/arm64/kvm/hyp/include/nvhe/fixed_config.h b/arch/arm64/kvm/hyp/include/nvhe/fixed_config.h
> index 51f043649146..0034bfffced6 100644
> --- a/arch/arm64/kvm/hyp/include/nvhe/fixed_config.h
> +++ b/arch/arm64/kvm/hyp/include/nvhe/fixed_config.h
> @@ -52,10 +52,10 @@
>   *	Supported by KVM
>   */
>  #define PVM_ID_AA64PFR0_RESTRICT_UNSIGNED (\
> -	FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_EL0), ID_AA64PFR0_EL1_ELx_64BIT_ONLY) | \
> -	FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_EL1), ID_AA64PFR0_EL1_ELx_64BIT_ONLY) | \
> -	FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_EL2), ID_AA64PFR0_EL1_ELx_64BIT_ONLY) | \
> -	FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_EL3), ID_AA64PFR0_EL1_ELx_64BIT_ONLY) | \
> +	FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_EL0), ID_AA64PFR0_EL1_EL0_IMP) | \
> +	FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_EL1), ID_AA64PFR0_EL1_EL1_IMP) | \
> +	FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_EL2), ID_AA64PFR0_EL1_EL2_IMP) | \
> +	FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_EL3), ID_AA64PFR0_EL1_EL3_IMP) | \

If you are going to rework this, can we instead use something less
verbose such as SYS_FIELD_GET()?

There is also a series from Fuad moving things around, and maybe
that's the opportunity to rework this while limiting the amount of
cosmetic churn. Not to that this fixed config stuff needs to be
reworked in order to match the runtime feature enforcement that the
rest of KVM has adopted.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.