linux-kernel - Re: [PATCH 1/3] x86/quirks: Scan all busses for early PCI quirks

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Date:   Sat, 14 Nov 2020 00:40:10 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Bjorn Helgaas <helgaas@...nel.org>,
        "Guilherme G. Piccoli" <gpiccoli@...onical.com>
Cc:     linux-pci@...r.kernel.org, kexec@...ts.infradead.org,
        x86@...nel.org, linux-kernel@...r.kernel.org, bhelgaas@...gle.com,
        dyoung@...hat.com, bhe@...hat.com, vgoyal@...hat.com,
        mingo@...hat.com, bp@...en8.de, hpa@...or.com, andi@...stfloor.org,
        lukas@...ner.de, okaya@...nel.org, kernelfans@...il.com,
        ddstreet@...onical.com, gavin.guo@...onical.com,
        jay.vosburgh@...onical.com, kernel@...ccoli.net,
        shan.gavin@...ux.alibaba.com,
        Eric Biederman <ebiederm@...ssion.com>
Subject: Re: [PATCH 1/3] x86/quirks: Scan all busses for early PCI quirks

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