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From: Thomas Gleixner <tglx@kernel.org>
To: Bjoern Doebel <doebel@amazon.de>, stable@vger.kernel.org, Marc Zyngier
 <maz@kernel.org>, linux-arm-kernel@lists.infradead.org,
 linux-kernel@vger.kernel.org, David Woodhouse <dwmw@amazon.co.uk>, Ali
 Saidi <alisaidi@amazon.com>, David Arinzon <darinzon@amazon.com>, Zeev
 Zilberman <zeev@amazon.com>
Cc: Bjoern Doebel <doebel@amazon.de>
Subject: Re: [PATCH] irqchip/gic-v3-its: Reconfigure ITS from software state
 on resume
In-Reply-To: <akZPM6SeJiM8th0N@amazon.de>
References: <20260507183102.1897629-1-doebel@amazon.de>
 <akZPM6SeJiM8th0N@amazon.de>
Date: Thu, 02 Jul 2026 17:13:26 +0200
Message-ID: <87y0fto25l.ffs@fw13>
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On Thu, Jul 02 2026 at 11:57, Bjoern Doebel wrote:

> Hi all,
>
> gentle ping on this one.

Marc?

> Since the original posting I've re-validated the fix against current
> mainline:
>
>   - It still applies cleanly to v7.2-rc1 (and to v7.1.0).
>
>   - I reproduced the original failure on *stock* v7.2-rc1. On EC2
>     Graviton instances, hibernation resume fails 100% of the time: the
>     ITS comes back reset, MAPD/MAPTI are never replayed, and the ENA
>     NIC silently loses its LPIs:
>
>       ena 0000:00:05.0: ... didn't receive a MSI-X interrupt (cmd 3)
>       ena 0000:00:05.0: Failed to create IO CQ. error: -62
>
>     The instance then has no networking after resume.
>
>   - With this patch applied, the same kernel survives hibernate/resume
>     cleanly: 9/9 cycles with zero failures, across all three Graviton
>     generations (Graviton 2/3/4, i.e. Neoverse N1/V1/V2), networking
>     fully restored on every resume.
>
> As described in the previous message, this is the fallout from 713335b6ee29
> ("irqchip/gic-v3-its: Implement .msi_teardown() callback"): device
> teardown no longer happens across a suspend/resume that keeps the MSI
> domain, so the ITS is never reprogrammed and drops interrupts after the
> hardware has been reset.
>
> Could you take a look when you get a chance?
>
> Thanks,
> Bjoern
>
>
>
>
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