linux-kernel - Re: [PATCH v3 0/6] KVM: SVM: Enable AVIC for Zen4+ (if x2AVIC)

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Message-ID: <owztdzclln5pmgsuxgzt54vneiejtngdkujaebr7r35zx3f4lj@xvvhwvumkkha>
Date: Fri, 19 Sep 2025 16:12:58 +0530
From: Naveen N Rao <naveen@...nel.org>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 0/6] KVM: SVM: Enable AVIC for Zen4+ (if x2AVIC)

On Thu, Sep 18, 2025 at 05:21:30PM -0700, Sean Christopherson wrote:
> Enable AVIC by default for Zen4+, so long as x2AVIC is supported (which should
> be the case if AVIC is supported).
> 
> v3:
>  - Don't advise the user to enable force_avic. [Naveen]
>  - Gather AVIC related module params in avic.c (by moving code/helpers to
>    avic.c).
>  - Print "AVIC enabled" even when it's forced.
>  - Enable by default iff x2AVIC is supported.
>  - Use "auto" to select KVM's automatic/default behavior.
> 
> v2: https://lore.kernel.org/all/cover.1756993734.git.naveen@kernel.org
> 
> v1: http://lkml.kernel.org/r/20250626145122.2228258-1-naveen@kernel.org
> 
> Naveen N Rao (1):
>   KVM: SVM: Enable AVIC by default for Zen4+ if x2AVIC is support
> 
> Sean Christopherson (5):
>   KVM: SVM: Move x2AVIC MSR interception helper to avic.c
>   KVM: SVM: Update "APICv in x2APIC without x2AVIC" in avic.c, not svm.c
>   KVM: SVM: Always print "AVIC enabled" separately, even when force
>     enabled
>   KVM: SVM: Don't advise the user to do force_avic=y (when x2AVIC is
>     detected)
>   KVM: SVM: Move global "avic" variable to avic.c
> 
>  arch/x86/kvm/svm/avic.c | 149 +++++++++++++++++++++++++++++++++-------
>  arch/x86/kvm/svm/svm.c  |  62 +----------------
>  arch/x86/kvm/svm/svm.h  |   4 +-
>  3 files changed, 125 insertions(+), 90 deletions(-)

Thanks for putting this together! I have confirmed that this correctly 
enables AVIC by default on a Zen 5 system and does not do so on a Zen 1 
system.

For the series:
Tested-by: Naveen N Rao (AMD) <naveen@...nel.org>


- Naveen