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Date: Tue, 14 Jul 2026 14:32:51 +0530
From: Naveen N Rao <naveen@kernel.org>
To: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Sean Christopherson <seanjc@google.com>, 
	Borislav Petkov <bp@alien8.de>, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, 
	Paolo Bonzini <pbonzini@redhat.com>, Nikunj A Dadhania <nikunj@amd.com>, 
	Tianyu Lan <tiala@microsoft.com>, Dave Hansen <dave.hansen@linux.intel.com>, 
	Thomas Gleixner <tglx@kernel.org>
Subject: Re: [RFC PATCH v3 02/27] x86/apic: Drop savic_eoi() in favor of
 native_apic_msr_eoi() for Secure AVIC
Message-ID: <alX59ewiXXSx7J3R@blrnaveerao1>
References: <cover.1783490022.git.naveen@kernel.org>
 <36c039713c4b03c87b636635cb4c1f8b98c15eff.1783490022.git.naveen@kernel.org>
 <5f6bcceb-1c48-43e5-bafc-8f86676c4092@amd.com>
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On Mon, Jul 13, 2026 at 12:43:45PM -0500, Tom Lendacky wrote:
> On 7/8/26 01:32, Naveen N Rao (AMD) wrote:
> > Drop savic_eoi() in favor of using the native helper that writes to the
> > APIC_EOI MSR. savic_eoi() was added mainly to be able to handle
> > level-triggered interrupts. However, it relies on APIC_TMR indicating a
> > vector to be level-triggered, but APIC_TMR can never have a bit set
> > since it is only updated when the LAPIC accepts a level-triggered
> > interrupt. In the case of a Secure AVIC SEV-SNP guest, all
> > level-triggered interrupt sources are in the VMM (emulated IOAPIC
> > primarily) and KVM accepts them on behalf of the guest resulting in the
> > APIC_TMR in KVM APIC backing page having a bit set. This is never seen
> > by the guest, which has its own private APIC backing page. As such, the
> > savic_eoi() handler is dead code. Remove it.
> > 
> > Fixes: 43b6687ac877 ("x86/apic: Handle EOI writes for Secure AVIC guests")
> > Signed-off-by: Naveen N Rao (AMD) <naveen@kernel.org>
> 
> Another guest change which should be separate from this series.

Yes, I have called this out in the cover letter. I see now that I should 
have used a better subject for the cover letter though.

> 
> Is this causing issues with this hypervisor support or is just code that
> is never invoked? Do other hypervisors behave the same way and will
> removing this break them?

This is code that is never invoked and is independent of the hypervisor.  
No impact to hypervisor code.


- Naveen