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From: Marc Zyngier <maz@kernel.org>
To: Valentine Burley <valentine.burley@collabora.com>
Cc: "tabba" <tabba@google.com>, "broonie" <broonie@kernel.org>,
	"stable" <stable@vger.kernel.org>, "oupton" <oupton@kernel.org>,
	"joey.gouly" <joey.gouly@arm.com>,
	"suzuki.poulose" <suzuki.poulose@arm.com>,
	"yuzenghui" <yuzenghui@huawei.com>,
	"catalin.marinas" <catalin.marinas@arm.com>,
	"will" <will@kernel.org>,
	"Sascha.Bischoff" <Sascha.Bischoff@arm.com>,
	"sebott" <sebott@redhat.com>,
	"linux-arm-kernel" <linux-arm-kernel@lists.infradead.org>,
	"kvmarm" <kvmarm@lists.linux.dev>,
	"linux-kernel" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] KVM: arm64: Skip interrupts in LRs during EOIcount replay
Date: Sat, 07 Mar 2026 19:10:17 +0000	[thread overview]
Message-ID: <87y0k3cv6u.wl-maz@kernel.org> (raw)
In-Reply-To: <19cc98f6bc6.30a0020a4990004.9101239855762576863@collabora.com>

On Sat, 07 Mar 2026 18:29:05 +0000,
Valentine Burley <valentine.burley@collabora.com> wrote:
> 
> Hi Marc,
> 
> Thanks a lot for your reply.
> 
> On Sat, 07 Mar 2026 17:33:08 +0100  Marc Zyngier <maz@kernel.org> wrote
>  > I can't reproduce it locally, but in a crap integration, where the GIC
>  > is clocked at a few dozen MHz, this is far more likely to happen. I
>  > should dig that Lazor out of the bin and put it back in the test rig.
>  > 
>  > In retrospect, it is obvious. I just couldn't see it until then. Many
>  > thanks for going the extra mile and pointing out the core issue.
> 
> Appreciate the clarification!
> 
> We also have a few Lazor boards in our CI, and the Trogdors are indeed
> legendary for hitting all kinds of edge cases.

Right. Time to have a look at SBoyd's u-boot patches from last year!

> 
> <snip>
> 
>  > Could you please give the hack below a go on your setup? It seems to
>  > work for me, but given that I never observed the issue the first
>  > place...
> 
> I've tested this on my sc7180 Trogdor setup, and it completely 
> resolves the issue. The Cuttlefish VM now boots reliably.
>
> Tested-by: Valentine Burley <valentine.burley@collabora.com>

Awesome. I have since tweaked the patch a tiny bit to keep the restart
pointer per CPU instead of per vcpu, as this doesn't live beyond the
load/put sequence. I'll post it formally for you to confirm that the
updated version is still correct.

Thanks,

	M.

-- 
Jazz isn't dead. It just smells funny.

      reply	other threads:[~2026-03-07 19:10 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-07 11:59 [PATCH] KVM: arm64: Skip interrupts in LRs during EOIcount replay Valentine Burley
2026-03-07 16:33 ` Marc Zyngier
2026-03-07 18:29   ` Valentine Burley
2026-03-07 19:10     ` Marc Zyngier [this message]

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