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From: Oliver Upton <oliver.upton@linux.dev>
To: Shaoqin Huang <shahuang@redhat.com>
Cc: Marc Zyngier <maz@kernel.org>,
	kvmarm@lists.linux.dev, Mark Brown <broonie@kernel.org>,
	Eric Auger <eauger@redhat.com>, Sebastian Ott <sebott@redhat.com>,
	Cornelia Huck <cohuck@redhat.com>,
	James Morse <james.morse@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Zenghui Yu <yuzenghui@huawei.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 1/3] KVM: arm64: Disable fields that KVM doesn't know how to handle in ID_AA64PFR1_EL1
Date: Wed, 17 Jul 2024 23:09:08 -0700	[thread overview]
Message-ID: <ZpixhBjsqhWTpEQH@linux.dev> (raw)
In-Reply-To: <20240718035017.434996-2-shahuang@redhat.com>

Hi Shaoqin,

On Wed, Jul 17, 2024 at 11:50:14PM -0400, Shaoqin Huang wrote:
> For some of the fields in the ID_AA64PFR1_EL1 register, KVM doesn't know
> how to handle them right now. So explicitly disable them in the register
> accessor, then those fields value will be masked to 0 even if on the
> hardware the field value is 1.

It is probably important to note that the only reason this is safe to do
from a UAPI POV is that read_sanitised_ftr_reg() doesn't yet return a
nonzero value for any of these fields.

-- 
Thanks,
Oliver


  reply	other threads:[~2024-07-18  6:09 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-07-18  3:50 [PATCH v4 0/3] Allow userspace to change ID_AA64PFR1_EL1 Shaoqin Huang
2024-07-18  3:50 ` [PATCH v4 1/3] KVM: arm64: Disable fields that KVM doesn't know how to handle in ID_AA64PFR1_EL1 Shaoqin Huang
2024-07-18  6:09   ` Oliver Upton [this message]
2024-07-18  6:58     ` Shaoqin Huang
2024-07-18  3:50 ` [PATCH v4 2/3] KVM: arm64: Allow userspace to change ID_AA64PFR1_EL1 Shaoqin Huang
2024-07-18  6:35   ` Oliver Upton
2024-07-18  8:21     ` Shaoqin Huang
2024-07-18  3:50 ` [PATCH v4 3/3] KVM: selftests: aarch64: Add writable test for ID_AA64PFR1_EL1 Shaoqin Huang

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