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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Dexuan Cui <decui@microsoft.com>,
        Saeed Mahameed <saeed@kernel.org>,
        Leon Romanovsky <leon@kernel.org>
Cc:     "linux-pci\@vger.kernel.org" <linux-pci@vger.kernel.org>,
        "'netdev\@vger.kernel.org'" <netdev@vger.kernel.org>,
        "'x86\@kernel.org'" <x86@kernel.org>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        "'linux-kernel\@vger.kernel.org'" <linux-kernel@vger.kernel.org>
Subject: RE: [5.14-rc1] mlx5_core receives no interrupts with maxcpus=8
In-Reply-To: <BYAPR21MB127077DE03164CA31AE0B33DBFE19@BYAPR21MB1270.namprd21.prod.outlook.com>
References: <BYAPR21MB12703228F3E7A8B8158EB054BF129@BYAPR21MB1270.namprd21.prod.outlook.com> <BYAPR21MB127099BADA8490B48910D3F1BF129@BYAPR21MB1270.namprd21.prod.outlook.com> <YPPwel8mhaIdHP1y@unreal> <c61af64fd275b3a329bbad699de9db661e3cf082.camel@kernel.org> <BYAPR21MB127077DE03164CA31AE0B33DBFE19@BYAPR21MB1270.namprd21.prod.outlook.com>
Date:   Wed, 21 Jul 2021 23:16:41 +0200
Message-ID: <87czrbpdty.ffs@nanos.tec.linutronix.de>
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Dexuan,

On Mon, Jul 19 2021 at 20:33, Dexuan Cui wrote:
> This is a bare metal x86-64 host with Intel CPUs. Yes, I believe the
> issue is in the IOMMU Interrupt Remapping mechanism rather in the
> NIC driver. I just don't understand why bringing the CPUs online and
> offline can work around the issue. I'm trying to dump the IOMMU IR
> table entries to look for any error. 

can you please enable GENERIC_IRQ_DEBUGFS and provide the output of

cat /sys/kernel/debug/irq/irqs/$THENICIRQS

Thanks,

        tglx