linux-kernel - Re: [PATCH] PCI: DPC: Clear AER status bits before disabling port containment

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Message-ID: <20180619215720.GE33049@bhelgaas-glaptop.roam.corp.google.com>
Date:   Tue, 19 Jun 2018 16:57:20 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Keith Busch <keith.busch@...el.com>
Cc:     Sinan Kaya <okaya@...eaurora.org>,
        Alexandru Gagniuc <mr.nuke.me@...il.com>, bhelgaas@...gle.com,
        alex_gagniuc@...lteam.com, austin_bolen@...l.com,
        shyam_iyer@...l.com, Dongdong Liu <liudongdong3@...wei.com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: DPC: Clear AER status bits before disabling port
 containment

On Wed, May 16, 2018 at 05:12:21PM -0600, Keith Busch wrote:
> On Wed, May 16, 2018 at 06:44:22PM -0400, Sinan Kaya wrote:
> > On 5/16/2018 5:33 PM, Alexandru Gagniuc wrote:
> > > AER status bits are sticky, and they survive system resets. Downstream
> > > devices are usually taken care of after re-enumerating the downstream
> > > busses, as the AER bits are cleared during probe().
> > > 
> > > However, nothing clears the bits of the port which contained the
> > > error. These sticky bits may leave some BIOSes to think that something
> > > bad happened, and print ominous messages on next boot. To prevent this,
> > > tidy up the AER status bits before releasing containment.
> > > 
> > > Signed-off-by: Alexandru Gagniuc <mr.nuke.me@...il.com>
> > > ---
> > >  drivers/pci/pcie/dpc.c | 4 ++++
> > >  1 file changed, 4 insertions(+)
> > > 
> > > diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
> > > index 8c57d607e603..bf82d6936556 100644
> > > --- a/drivers/pci/pcie/dpc.c
> > > +++ b/drivers/pci/pcie/dpc.c
> > > @@ -112,6 +112,10 @@ static void dpc_work(struct work_struct *work)
> > >  		dpc->rp_pio_status = 0;
> > >  	}
> > >  
> > > +	/* DPC event made a mess of our AER status bits. Clean them up. */
> > > +	pci_cleanup_aer_error_status_regs(pdev);
> > > +	/* TODO: Should we also use aer_print_error to log the event? */
> > > +
> > >  	pci_write_config_word(pdev, cap + PCI_EXP_DPC_STATUS,
> > >  		PCI_EXP_DPC_STATUS_TRIGGER | PCI_EXP_DPC_STATUS_INTERRUPT);
> > >  
> > > 
> > 
> > I think Keith has a patch to fix this. It was under review at some point.
> 
> Right, I do intend to following up on this, but I've had some trouble
> finding time the last few weeks. Sorry about that, things will clear up
> for me shortly.

I'll drop this (Alexandru's) patch for now, waiting for your update, Keith.