Re: [PATCH V3] AER: aer_root_reset() non-native handling

[Sean V Kelley]

On 14 Nov 2020, at 7:37, Bjorn Helgaas wrote:

> On Wed, Nov 04, 2020 at 03:22:44PM -0800, Sean V Kelley wrote:
> > If an OS has not been granted AER control via _OSC, then
> > the OS should not make changes to PCI_ERR_ROOT_COMMAND and
> > PCI_ERR_ROOT_STATUS related registers. Per section 4.5.1 of
> > the System Firmware Intermediary (SFI) _OSC and DPC Updates
> > ECN [1], this bit also covers these aspects of the PCI
> > Express Advanced Error Reporting. Based on the above and
> > earlier discussion [2], make the following changes:
> >
> > Add a check for the native case (i.e., AER control via _OSC)
> >
> > Note that the current "clear, reset, enable" order suggests that the
> > reset might cause errors that we should ignore. Lacking historical
> > context, these will be retained.
> >
> > [1] System Firmware Intermediary (SFI) _OSC and DPC Updates ECN, Feb 
> > 24,
> >     2020, affecting PCI Firmware Specification, Rev. 3.2
> >     https://members.pcisig.com/wg/PCI-SIG/document/14076
> > [2] 
> > https://lore.kernel.org/linux-pci/20201020162820.GA370938@bjorn-Precision-5520/
> >
> > Signed-off-by: Sean V Kelley <sean.v.kelley@xxxxxxxxx>
>
> What do I do with this patch in combination with "[PATCH v10 00/16]
> Add RCEC handling to PCI/AER"?  I tried applying this and the RCEC
> series on top, but they conflict.
>
> I was thinking it would be easiest to include this as the first patch
> in the series so I wouldn't have to resolve the conflicts, but maybe
> you had something else in mind?

It originally did rebase but the last minute %s/root/dev changes may 
have broke the rebase.
Will fix and submit as the first patch in the RCEC series.


> > ---
> > Changes since V2 :
> >
> > Fixed an unfortunate copy/paste error.
> >
> > Changes since V1 [1]:
> >
> > Noted lack of historical context on isolation of both the
> > pci_bus_error_reset() and the clearing of Root Error Status. In fact,
> > the call to aer_enable_rootport() likewise disables system error 
> > generation
> > in response to error messages around the clearing of the error 
> > status. So
> > retained the wrapping of the  "clear, reset, enable".
> >
> > [1] 
> > https://lore.kernel.org/linux-pci/20201030223443.165783-1-sean.v.kelley@xxxxxxxxx/
> >
> > Thanks,
> >
> > Sean
> > ---
> >  drivers/pci/pcie/aer.c | 31 +++++++++++++++++--------------
> >  1 file changed, 17 insertions(+), 14 deletions(-)
> >
> > diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> > index 65dff5f3457a..4ab379fa1506 100644
> > --- a/drivers/pci/pcie/aer.c
> > +++ b/drivers/pci/pcie/aer.c
> > @@ -1358,26 +1358,29 @@ static int aer_probe(struct pcie_device *dev)
> >  static pci_ers_result_t aer_root_reset(struct pci_dev *dev)
> >  {
> >  	int aer = dev->aer_cap;
> > +	int rc = 0;
>
> Unnecessary init, I think.

Will remove init.

Thanks,

Sean

> >  	u32 reg32;
> > -	int rc;
> > -
> >
> > -	/* Disable Root's interrupt in response to error messages */
> > -	pci_read_config_dword(dev, aer + PCI_ERR_ROOT_COMMAND, &reg32);
> > -	reg32 &= ~ROOT_PORT_INTR_ON_MESG_MASK;
> > -	pci_write_config_dword(dev, aer + PCI_ERR_ROOT_COMMAND, reg32);
> > +	if (pcie_aer_is_native(dev)) {
> > +		/* Disable Root's interrupt in response to error messages */
> > +		pci_read_config_dword(dev, aer + PCI_ERR_ROOT_COMMAND, &reg32);
> > +		reg32 &= ~ROOT_PORT_INTR_ON_MESG_MASK;
> > +		pci_write_config_dword(dev, aer + PCI_ERR_ROOT_COMMAND, reg32);
> > +	}
> >
> >  	rc = pci_bus_error_reset(dev);
> > -	pci_info(dev, "Root Port link has been reset\n");
> > +	pci_info(dev, "Root Port link has been reset (%d)\n", rc);
> >
> > -	/* Clear Root Error Status */
> > -	pci_read_config_dword(dev, aer + PCI_ERR_ROOT_STATUS, &reg32);
> > -	pci_write_config_dword(dev, aer + PCI_ERR_ROOT_STATUS, reg32);
> > +	if (pcie_aer_is_native(dev)) {
> > +		/* Clear Root Error Status */
> > +		pci_read_config_dword(dev, aer + PCI_ERR_ROOT_STATUS, &reg32);
> > +		pci_write_config_dword(dev, aer + PCI_ERR_ROOT_STATUS, reg32);
> >
> > -	/* Enable Root Port's interrupt in response to error messages */
> > -	pci_read_config_dword(dev, aer + PCI_ERR_ROOT_COMMAND, &reg32);
> > -	reg32 |= ROOT_PORT_INTR_ON_MESG_MASK;
> > -	pci_write_config_dword(dev, aer + PCI_ERR_ROOT_COMMAND, reg32);
> > +		/* Enable Root Port's interrupt in response to error messages */
> > +		pci_read_config_dword(dev, aer + PCI_ERR_ROOT_COMMAND, &reg32);
> > +		reg32 |= ROOT_PORT_INTR_ON_MESG_MASK;
> > +		pci_write_config_dword(dev, aer + PCI_ERR_ROOT_COMMAND, reg32);
> > +	}
> >
> >  	return rc ? PCI_ERS_RESULT_DISCONNECT : PCI_ERS_RESULT_RECOVERED;
> >  }
> > --
> > 2.29.2