linux-kernel - Re: [PATCH 03/16] KVM: arm64: Avoid remapping the SVE state in the hyp stage-1

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Message-ID: <YW1OQNuq5Gdd9jpQ@google.com>
Date:   Mon, 18 Oct 2021 11:36:48 +0100
From:   Quentin Perret <qperret@...gle.com>
To:     Marc Zyngier <maz@...nel.org>
Cc:     James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Fuad Tabba <tabba@...gle.com>,
        David Brazdil <dbrazdil@...gle.com>,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org, kernel-team@...roid.com
Subject: Re: [PATCH 03/16] KVM: arm64: Avoid remapping the SVE state in the
 hyp stage-1

On Saturday 16 Oct 2021 at 12:04:15 (+0100), Marc Zyngier wrote:
> I actually ended-up implementing a similar patch as part of my 'first
> run' series[1], though I moved the mapping to the point where we
> finalise the vcpu as that's where the allocation takes place.
> 
> Do you see any potential issue with that approach?

Nope, and in fact I think your patch should allow to simplify a bit
kvm_arm_vcpu_destroy() for me, as checking arch.sve_state != NULL would
now be sufficient to know if the sve state has been shared -- checking
arch.has_run_once is no longer needed.

I'll base v2 on this.

Thanks!
Quentin