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From: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
To: Marc Zyngier <maz@kernel.org>, kvmarm@lists.linux.dev,
	kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Cc: Joey Gouly <joey.gouly@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Oliver Upton <oliver.upton@linux.dev>,
	Zenghui Yu <yuzenghui@huawei.com>,
	Eric Auger <eric.auger@redhat.com>
Subject: Re: [PATCH 01/14] arm64: cpufeature: Handle NV_frac as a synonym of
 NV2
In-Reply-To: <20250215173816.3767330-2-maz@kernel.org>
References: <20250215173816.3767330-1-maz@kernel.org>
 <20250215173816.3767330-2-maz@kernel.org>
Date: Mon, 24 Feb 2025 13:11:18 +0530
Message-ID: <yq5a7c5fhjs1.fsf@kernel.org>
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Marc Zyngier <maz@kernel.org> writes:

> With ARMv9.5, an implementation supporting Nested Virtualization
> is allowed to only support NV2, and to avoid supporting the old
> (and useless) ARMv8.3 variant.
>
> This is indicated by ID_AA64MMFR2_EL1.NV being 0 (as if NV wasn't
> implemented) and ID_AA64MMDR4_EL1.NV_frac being 1 (indicating that
                            ^ F
The register name is wrong there.

> NV2 is actually supported).
>

-aneesh