linux-kernel - Re: [PATCH v9 03/10] arm64/kvm: expose FEAT_MTE_TAGGED

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Message-ID: <aFrTcGt-g5sc-uv0@arm.com>
Date: Tue, 24 Jun 2025 17:33:52 +0100
From: Catalin Marinas <catalin.marinas@....com>
To: Marc Zyngier <maz@...nel.org>
Cc: Yeoreum Yun <yeoreum.yun@....com>, pcc@...gle.com, will@...nel.org,
	broonie@...nel.org, anshuman.khandual@....com, joey.gouly@....com,
	yury.khrustalev@....com, oliver.upton@...ux.dev,
	frederic@...nel.org, akpm@...ux-foundation.org, surenb@...gle.com,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org
Subject: Re: [PATCH v9 03/10] arm64/kvm: expose FEAT_MTE_TAGGED_FAR feature
 to guest

Hi Marc,

On Wed, Jun 18, 2025 at 05:43:07PM +0100, Marc Zyngier wrote:
> In general, please use a patch title format that matches the one used
> for the subsystem. For KVM, that'd be "KVM: arm64: Expose ..."/
[...]
> >  	case SYS_ID_AA64PFR2_EL1:
> > -		/* We only expose FPMR */
> > -		val &= ID_AA64PFR2_EL1_FPMR;
> > +		mask = ID_AA64PFR2_EL1_FPMR;
> > +
> > +		if (kvm_has_mte(vcpu->kvm))
> > +			mask |= ID_AA64PFR2_EL1_MTEFAR;
> > +
> > +		val &= mask;
> 
> I don't think there is a need for an extra variable, and you could
> follow the pattern established in this file by writing this as:
> 
> 	val &= (ID_AA64PFR2_EL1_FPMR |
> 		(kvm_has_mte(vcpu->kvm) ? ID_AA64PFR2_EL1_MTEFAR : 0));
> 
> Not a big deal though.

I can make the changes locally. Are you ok with the patch otherwise?

-- 
Catalin