linux-kernel - Re: xhci_pci & PCIe hotplug crash

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Message-ID: <20210619075358.GA31639@wunner.de>
Date:   Sat, 19 Jun 2021 09:53:58 +0200
From:   Lukas Wunner <lukas@...ner.de>
To:     Pali Rohár <pali@...nel.org>
Cc:     David Laight <David.Laight@...LAB.COM>,
        Greg KH <gregkh@...uxfoundation.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Marek Behún <kabel@...nel.org>
Subject: Re: xhci_pci & PCIe hotplug crash

On Wed, May 05, 2021 at 05:39:42PM +0200, Pali Rohár wrote:
> On Wednesday 05 May 2021 15:20:11 David Laight wrote:
> > From: Pali Rohár
> > Sent: 05 May 2021 14:03
> > > So seems that PCIe controller HW triggers these external aborts when
> > > device on PCIe bus is not accessible anymore.
> > > 
> > > If this issue is really caused by MMIO access from xhci driver when
> > > device is not accessible on the bus anymore, can we do something to
> > > prevent this kernel crash? Somehow mask that external abort in kernel
> > > for a time during MMIO access?
> > 
> > If it is a cycle abort then the interrupted address is probably
> > that of the MMIO instruction.
> > So you need to catch the abort, emulate the instruction and
> > then return to the next one.
> 
> Has kernel API & infrastructure for catching these aborts and executing
> own driver handler when abort happens?

Yes, see here for an example:

https://lore.kernel.org/linux-pci/20210615191405.21878-4-jim2101024@gmail.com/