From: <Alex_Gagniuc@Dellteam.com>
To: <helgaas@kernel.org>
Cc: <oohall@gmail.com>, <gregkh@linuxfoundation.org>,
<keith.busch@intel.com>, <mr.nuke.me@gmail.com>,
<linux-pci@vger.kernel.org>, <Austin.Bolen@dell.com>,
<Shyam.Iyer@dell.com>, <linux-kernel@vger.kernel.org>,
<jonathan.derrick@intel.com>, <lukas@wunner.de>,
<ruscur@russell.cc>, <sbobroff@linux.ibm.com>,
<linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH v2] PCI/MSI: Don't touch MSI bits when the PCI device is disconnected
Date: Tue, 13 Nov 2018 22:39:15 +0000 [thread overview]
Message-ID: <19136f44cd5c45e79bbef7e78a6bf332@ausx13mps321.AMER.DELL.COM> (raw)
In-Reply-To: 20181113050240.GA182139@google.com
On 11/12/2018 11:02 PM, Bjorn Helgaas wrote:
>
> [EXTERNAL EMAIL]
> Please report any suspicious attachments, links, or requests for sensitive information.
>
>
> [+cc Jon, for related VMD firmware-first error enable issue]
>
> On Mon, Nov 12, 2018 at 08:05:41PM +0000, Alex_Gagniuc@Dellteam.com wrote:
>> On 11/11/2018 11:50 PM, Oliver O'Halloran wrote:
>>> On Thu, 2018-11-08 at 23:06 +0000, Alex_Gagniuc@Dellteam.com wrote:
>
>>>> But it's not the firmware that crashes. It's linux as a result of a
>>>> fatal error message from the firmware. And we can't fix that because FFS
>>>> handling requires that the system reboots [1].
>>>
>>> Do we know the exact circumsances that result in firmware requesting a
>>> reboot? If it happen on any PCIe error I don't see what we can do to
>>> prevent that beyond masking UEs entirely (are we even allowed to do
>>> that on FFS systems?).
>>
>> Pull a drive out at an angle, push two drives in at the same time, pull
>> out a drive really slow. If an error is even reported to the OS depends
>> on PD state, and proprietary mechanisms and logic in the HW and FW. OS
>> is not supposed to mask errors (touch AER bits) on FFS.
>
> PD?
Presence Detect
> Do you think Linux observes the rule about not touching AER bits on
> FFS? I'm not sure it does. I'm not even sure what section of the
> spec is relevant.
I haven't found any place where linux breaks this rule. I'm very
confident that, unless otherwise instructed, we follow this rule.
> The whole issue of firmware-first, the mechanism by which firmware
> gets control, the System Error enables in Root Port Root Control
> registers, etc., is very murky to me. Jon has a sort of similar issue
> with VMD where he needs to leave System Errors enabled instead of
> disabling them as we currently do.
Well, OS gets control via _OSC method, and based on that it should
touch/not touch the AER bits. The bits that get set/cleared come from
_HPX method, and there's a more about the FFS described in ACPI spec. It
seems that if platform, wants to enable VMD, it should pass the correct
bits via _HPX. I'm curious to know in what new twisted way FFS doesn't
work as intended.
Alex
> Bjorn
>
> [1] https://lore.kernel.org/linux-pci/20181029210651.GB13681@bhelgaas-glaptop.roam.corp.google.com
>
next prev parent reply other threads:[~2018-11-13 22:39 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-18 22:15 [PATCH v2] PCI/MSI: Don't touch MSI bits when the PCI device is disconnected Alexandru Gagniuc
2018-11-06 0:32 ` Alex G.
2018-11-07 17:04 ` Derrick, Jonathan
2018-11-07 23:42 ` Bjorn Helgaas
2018-11-08 20:09 ` Bjorn Helgaas
2018-11-08 21:49 ` Keith Busch
2018-11-08 22:01 ` Greg Kroah-Hartman
2018-11-08 22:32 ` Keith Busch
2018-11-08 22:42 ` Greg Kroah-Hartman
2018-11-08 22:49 ` Alex_Gagniuc
2018-11-08 22:51 ` Greg KH
2018-11-08 23:06 ` Alex_Gagniuc
2018-11-12 5:49 ` Oliver O'Halloran
2018-11-12 20:05 ` Alex_Gagniuc
2018-11-13 5:02 ` Bjorn Helgaas
2018-11-13 22:39 ` Alex_Gagniuc [this message]
2018-11-13 22:52 ` Keith Busch
2018-11-14 0:31 ` Alex_Gagniuc
2018-11-14 5:59 ` Bjorn Helgaas
2018-11-14 19:22 ` Alex_Gagniuc
2018-11-14 19:41 ` Derrick, Jonathan
2018-11-14 20:23 ` Keith Busch
2018-11-14 20:52 ` Alex_Gagniuc
2018-11-14 20:58 ` Keith Busch
2018-11-15 6:24 ` Bjorn Helgaas
2018-11-16 0:19 ` Alex_Gagniuc
2018-11-08 23:03 ` Keith Busch
2018-11-09 7:29 ` Lukas Wunner
2018-11-09 11:32 ` Greg Kroah-Hartman
2018-11-09 16:36 ` Keith Busch
2018-11-08 22:20 ` Alex_Gagniuc
2018-11-09 7:11 ` Lukas Wunner
2018-11-12 5:48 ` Oliver O'Halloran
2018-12-27 19:28 ` Alex_Gagniuc
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