linux-kernel - Re: [PATCH] KVM: arm64: Add missing ERX*

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Message-ID: <ZaVFmtKbtCJtaAAu@linux.dev>
Date: Mon, 15 Jan 2024 14:47:54 +0000
From: Oliver Upton <oliver.upton@...ux.dev>
To: Marc Zyngier <maz@...nel.org>
Cc: Ruidong Tian <tianruidong@...ux.alibaba.com>, kvmarm@...ts.linux.dev,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	james.morse@....com, suzuki.poulose@....com, yuzenghui@...wei.com,
	catalin.marinas@....com, will@...nel.org
Subject: Re: [PATCH] KVM: arm64: Add missing ERX*_EL1 registers

On Wed, Jan 10, 2024 at 12:20:30PM +0000, Marc Zyngier wrote:
> If my reading of the ARM ARM is correct, these registers only exist if
> FEAT_RASv1p1 is implemented. Which means that we shouldn't handle
> those as RAZ/WI unconditionally, but instead check for what we
> advertise to the guest and handle it accordingly.

Can we go a step further and just stop advertising RAS to guests? I don't
expect VMs to gain much from our RAZ/WI implementation. Conditional
RAZ/WI would still be helpful in this case for migrated VMs that have
'seen' the feature.

-- 
Thanks,
Oliver