linux-kernel - Re: [PATCH 03/10] KVM: arm64: switch HCRX

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Message-ID: <d61573bb-07be-5abe-4ca5-8649ac79e430@arm.com>
Date:   Wed, 22 Feb 2023 18:36:19 +0000
From:   Kristina Martsenko <kristina.martsenko@....com>
To:     Mark Brown <broonie@...nel.org>
Cc:     linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>,
        Oliver Upton <oliver.upton@...ux.dev>,
        James Morse <james.morse@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Zenghui Yu <yuzenghui@...wei.com>,
        Mark Rutland <mark.rutland@....com>,
        Luis Machado <luis.machado@....com>,
        Vladimir Murzin <vladimir.murzin@....com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 03/10] KVM: arm64: switch HCRX_EL2 between host and guest

On 16/02/2023 16:20, Mark Brown wrote:
> On Thu, Feb 16, 2023 at 04:00:05PM +0000, Kristina Martsenko wrote:
> 
>> After this change, SMPME is no longer set for guests, which should have
>> no effect as SME is currently disabled for guests.
> 
> SMPME is mainly set for the benefit of any future guests, it is
> used to turn off SME priorities for guests.  While it's true that
> we don't have any guests support yet it's there as safety to
> ensure we don't forget to enable it later on or something
> otherwise goes wrong.  We don't need priority mapping on the host
> since we don't have any priority mapping support at all, and it's
> difficult to see a reason why we would want to remap our own
> priorities in the host.

That makes sense. I'll fix this in v2 so that priority mapping is enabled for
guests and disabled for the host.

Thanks,
Kristina