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Date:   Thu, 30 Sep 2021 11:22:58 +0100
Message-ID: <87bl4atla5.wl-maz@kernel.org>
From:   Marc Zyngier <maz@kernel.org>
To:     David Brazdil <dbrazdil@google.com>
Cc:     linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org,
        kvmarm@lists.cs.columbia.edu, ascull@google.com,
        James Morse <james.morse@arm.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Alexandru Elisei <alexandru.elisei@arm.com>,
        kernel-team@android.com
Subject: Re: [PATCH] KVM: arm64: Allow KVM to be disabled from the command line
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Hi David,

On Tue, 28 Sep 2021 15:58:08 +0100,
David Brazdil <dbrazdil@google.com> wrote:
> 
> Hey Marc,
> that all makes sense:
> 
> Reviewed-by: David Brazdil <dbrazdil@google.com>
> 
> > @@ -2137,8 +2142,15 @@ static int __init early_kvm_mode_cfg(char *arg)
> >  		return 0;
> >  	}
> >  
> > -	if (strcmp(arg, "nvhe") == 0 && !WARN_ON(is_kernel_in_hyp_mode()))
> > +	if (strcmp(arg, "nvhe") == 0 && !WARN_ON(is_kernel_in_hyp_mode())) {
> > +		kvm_mode = KVM_MODE_DEFAULT;
> >  		return 0;
> > +	}
> > +
> > +	if (strcmp(arg, "none") == 0 && !WARN_ON(is_kernel_in_hyp_mode())) {
> nit: I noticed we check is_kernel_in_hyp_mode here for nvhe/none but for
> protected it is checked in is_kvm_protected_mode. May be worth unifying?

is_kvm_protected_mode() drives a capability (as we rely on the
associated static key), and we don't need this with either 'nvhe' nor
'none'.

So I'm unsure what we can unify, to be honest. Can you suggest a
patch?

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.