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From: Sean Christopherson <seanjc@google.com>
To: David Woodhouse <dwmw2@infradead.org>
Cc: Khushit Shah <khushit.shah@nutanix.com>,
	pbonzini@redhat.com, kai.huang@intel.com,  mingo@redhat.com,
	x86@kernel.org, bp@alien8.de, hpa@zytor.com,
	 linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	 dave.hansen@linux.intel.com, tglx@linutronix.de,
	jon@nutanix.com,  shaju.abraham@nutanix.com
Subject: Re: [PATCH v5 4/3] KVM: selftests: Add test cases for EOI suppression modes
Date: Thu, 29 Jan 2026 07:19:00 -0800	[thread overview]
Message-ID: <aXt6ZEgZRGPPPtTB@google.com> (raw)
In-Reply-To: <83f9b0a5dd0bc1de9d1e61954f6dd5211df45163.camel@infradead.org>

On Wed, Jan 28, 2026, David Woodhouse wrote:
> From: David Woodhouse <dwmw@amazon.co.uk>
> 
> Rather than being frightened of doing the right thing for the in-kernel
> I/O APIC because "there might be bugs", 

I'm not worried about bugs per se, I'm worried about breaking existing guests.
Even if KVM is 100% perfect, changes in behavior can still break guests,
especially for a feature like this where it seems like everyone got it wrong.

And as I said before, I'm not opposed to supporting directed EOI in the in-kernel
I/O APIC, but (a) I don't want to do it in conjunction with the fixes for stable@,
and (b) I'd prefer to not bother unless there's an actual use case for doing so.
The in-kernel I/O APIC isn't being deprecated, but AFAIK it's being de-prioritized
by pretty much every VMM.  I.e. the risk vs. reward isn't there for me.

  reply	other threads:[~2026-01-29 15:19 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-12-29 11:17 [PATCH v5 0/3] KVM: x86: Add userspace control for Suppress EOI Broadcast Khushit Shah
2025-12-29 11:17 ` [PATCH v5 1/3] KVM: x86: Refactor suppress EOI broadcast logic Khushit Shah
2026-01-02 16:23   ` David Woodhouse
2026-01-12  4:15     ` Khushit Shah
2026-01-13 23:40       ` David Woodhouse
2026-01-14  0:10       ` Sean Christopherson
2026-01-16  4:41         ` Khushit Shah
2026-01-16  9:01         ` David Woodhouse
2026-01-16 10:02           ` Khushit Shah
2026-01-16 17:34             ` Sean Christopherson
2026-01-23 13:04               ` Khushit Shah
2026-01-13 23:11   ` Sean Christopherson
2025-12-29 11:17 ` [PATCH v5 2/3] KVM: x86/ioapic: Implement support for I/O APIC version 0x20 with EOIR Khushit Shah
2025-12-29 11:39   ` David Woodhouse
2025-12-29 12:21     ` Khushit Shah
2025-12-29 13:01       ` David Woodhouse
2025-12-29 15:16         ` Khushit Shah
2025-12-29 15:36           ` David Woodhouse
2025-12-29 15:57             ` Khushit Shah
2026-01-02 16:17               ` David Woodhouse
2026-01-12  3:22                 ` Khushit Shah
2025-12-29 11:17 ` [PATCH v5 3/3] KVM: x86: Add x2APIC "features" to control EOI broadcast suppression Khushit Shah
2026-01-02 16:41   ` David Woodhouse
2026-01-12  3:27     ` Khushit Shah
2026-01-29  4:49 ` [PATCH v5 4/3] KVM: selftests: Add test cases for EOI suppression modes David Woodhouse
2026-01-29 15:19   ` Sean Christopherson [this message]
2026-01-29 15:58     ` David Woodhouse
2026-02-04  0:00       ` Sean Christopherson

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