linux-kernel - Re: [PATCH] PCI: layerscape: Change back to the default error response behavior

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Date:   Wed, 30 Sep 2020 10:07:58 -0500
From:   Rob Herring <robh@...nel.org>
To:     Kishon Vijay Abraham I <kishon@...com>
Cc:     Zhiqiang Hou <Zhiqiang.Hou@....com>,
        PCI <linux-pci@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Minghuan Lian <minghuan.Lian@....com>,
        Roy Zang <roy.zang@....com>, Mingkai Hu <mingkai.hu@....com>,
        Yang-Leo Li <leoyang.li@....com>
Subject: Re: [PATCH] PCI: layerscape: Change back to the default error
 response behavior

On Wed, Sep 30, 2020 at 8:29 AM Kishon Vijay Abraham I <kishon@...com> wrote:
>
> Hi Hou,
>
> On 29/09/20 6:43 pm, Zhiqiang Hou wrote:
> > From: Hou Zhiqiang <Zhiqiang.Hou@....com>
> >
> > In the current error response behavior, it will send a SLVERR response
> > to device's internal AXI slave system interface when the PCIe controller
> > experiences an erroneous completion (UR, CA and CT) from an external
> > completer for its outbound non-posted request, which will result in
> > SError and crash the kernel directly.
> > This patch change back it to the default behavior to increase the
> > robustness of the kernel. In the default behavior, it always sends an
> > OKAY response to the internal AXI slave interface when the controller
> > gets these erroneous completions. And the AER driver will report and
> > try to recover these errors.
>
> I don't think not forwarding any error interrupts is a good idea.

Interrupts would be fine. Abort/SError is not. I think it is pretty
clear what the correct behavior is for config accesses.

> Maybe
> you could disable it while reading configuration space registers
> (vendorID and deviceID) and then enable error forwarding back?

To add to the locking (or lack of) problems in config accesses?

Rob