linux-kernel - Re: [PATCH v3 15/62] KVM: SVM: Drop superfluous "cache" of AVIC Physical ID entry pointer

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Message-ID: <bknceu6nswhlz2c6lx3zc4afnrmq63dsriqctexincvs5jjk6v@7wlm2lf4czlh>
Date: Thu, 19 Jun 2025 16:39:37 +0530
From: Naveen N Rao <naveen@...nel.org>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	Paolo Bonzini <pbonzini@...hat.com>, Joerg Roedel <joro@...tes.org>, 
	David Woodhouse <dwmw2@...radead.org>, Lu Baolu <baolu.lu@...ux.intel.com>, 
	linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev, kvm@...r.kernel.org, 
	iommu@...ts.linux.dev, linux-kernel@...r.kernel.org, Sairaj Kodilkar <sarunkod@....com>, 
	Vasant Hegde <vasant.hegde@....com>, Maxim Levitsky <mlevitsk@...hat.com>, 
	Joao Martins <joao.m.martins@...cle.com>, Francesco Lavra <francescolavra.fl@...il.com>, 
	David Matlack <dmatlack@...gle.com>
Subject: Re: [PATCH v3 15/62] KVM: SVM: Drop superfluous "cache" of AVIC
 Physical ID entry pointer

On Wed, Jun 11, 2025 at 03:45:18PM -0700, Sean Christopherson wrote:
> Drop the vCPU's pointer to its AVIC Physical ID entry, and simply index
> the table directly.  Caching a pointer address is completely unnecessary
> for performance, and while the field technically caches the result of the
> pointer calculation, it's all too easy to misinterpret the name and think
> that the field somehow caches the _data_ in the table.
> 
> No functional change intended.
> 
> Suggested-by: Maxim Levitsky <mlevitsk@...hat.com>
> Tested-by: Sairaj Kodilkar <sarunkod@....com>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>  arch/x86/kvm/svm/avic.c | 27 +++++++++++++++------------
>  arch/x86/kvm/svm/svm.h  |  1 -
>  2 files changed, 15 insertions(+), 13 deletions(-)

Reviewed-by: Naveen N Rao (AMD) <naveen@...nel.org>

- Naveen