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

From: Sean V Kelley
Date: Mon Nov 16 2020 - 12:10:48 EST


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