linux-kernel - Re: [PATCH v4 1/3] KVM: arm64: Disable fields that KVM doesn't know how to handle in ID_AA64PFR1

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Message-ID: <817b5f2b-ec69-4a66-ad7b-ea8c8b9d0f24@redhat.com>
Date: Thu, 18 Jul 2024 14:58:20 +0800
From: Shaoqin Huang <shahuang@...hat.com>
To: Oliver Upton <oliver.upton@...ux.dev>
Cc: Marc Zyngier <maz@...nel.org>, kvmarm@...ts.linux.dev,
 Mark Brown <broonie@...nel.org>, Eric Auger <eauger@...hat.com>,
 Sebastian Ott <sebott@...hat.com>, Cornelia Huck <cohuck@...hat.com>,
 James Morse <james.morse@....com>, Suzuki K Poulose
 <suzuki.poulose@....com>, Zenghui Yu <yuzenghui@...wei.com>,
 Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/3] KVM: arm64: Disable fields that KVM doesn't know
 how to handle in ID_AA64PFR1_EL1

Hi Oliver,

On 7/18/24 14:09, Oliver Upton wrote:
> 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.

(Reply again by the plain text)

Yeah. That would be more clear if I tell the reader this information. 
Will add this when updating.

Thanks,
Shaoqin

> 

-- 
Shaoqin