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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Bjorn Helgaas <helgaas@kernel.org>,
        "Guilherme G. Piccoli" <gpiccoli@canonical.com>
Cc:     linux-pci@vger.kernel.org, kexec@lists.infradead.org,
        x86@kernel.org, linux-kernel@vger.kernel.org, bhelgaas@google.com,
        dyoung@redhat.com, bhe@redhat.com, vgoyal@redhat.com,
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        lukas@wunner.de, okaya@kernel.org, kernelfans@gmail.com,
        ddstreet@canonical.com, gavin.guo@canonical.com,
        jay.vosburgh@canonical.com, kernel@gpiccoli.net,
        shan.gavin@linux.alibaba.com,
        Eric Biederman <ebiederm@xmission.com>
Subject: Re: [PATCH 1/3] x86/quirks: Scan all busses for early PCI quirks
In-Reply-To: <87ft5cltqa.fsf@nanos.tec.linutronix.de>
References: <20201113164638.GA1019448@bjorn-Precision-5520> <87ft5cltqa.fsf@nanos.tec.linutronix.de>
Date:   Sat, 14 Nov 2020 00:40:10 +0100
Message-ID: <87d00gltb9.fsf@nanos.tec.linutronix.de>
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Bjorn,

On Sat, Nov 14 2020 at 00:31, Thomas Gleixner wrote:
> On Fri, Nov 13 2020 at 10:46, Bjorn Helgaas wrote:
>> pci_device_shutdown() still clears the Bus Master Enable bit if we're
>> doing a kexec and the device is in D0-D3hot, which should also disable
>> MSI/MSI-X.  Why doesn't this solve the problem?  Is this because the
>> device causing the storm was in PCI_UNKNOWN state?
>
> That's indeed a really good question.

So we do that on kexec, but is that true when starting a kdump kernel
from a kernel crash? I doubt it.

Thanks,

        tglx