From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx> Fatal (DPC) error recovery is currently broken for non-hotplug capable devices. With current implementation, after successful fatal error recovery, non-hotplug capable device state won't be restored properly. You can find related issues in following links. https://lkml.org/lkml/2020/5/27/290 https://lore.kernel.org/linux-pci/12115.1588207324@famine/ https://lkml.org/lkml/2020/3/28/328 Current fatal error recovery implementation relies on hotplug handler for detaching/re-enumerating the affected devices/drivers on DLLSC state changes. So when dealing with non-hotplug capable devices, recovery code does not restore the state of the affected devices correctly. Correct implementation should call report_slot_reset() function after resetting the link to restore the state of the device/driver. So use PCI_ERS_RESULT_NEED_RESET as error status for successful reset_link() operation and use PCI_ERS_RESULT_DISCONNECT for failure case. PCI_ERS_RESULT_NEED_RESET error state will ensure slot_reset() is called after reset link operation which will also fix the above mentioned issue. [original patch is from jay.vosburgh@xxxxxxxxxxxxx] [original patch link https://lore.kernel.org/linux-pci/12115.1588207324@famine/] Fixes: 6d2c89441571 ("PCI/ERR: Update error status after reset_link()") Signed-off-by: Jay Vosburgh <jay.vosburgh@xxxxxxxxxxxxx> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx> --- drivers/pci/pcie/err.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c index 14bb8f54723e..5fe8561c7185 100644 --- a/drivers/pci/pcie/err.c +++ b/drivers/pci/pcie/err.c @@ -165,8 +165,28 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev, pci_dbg(dev, "broadcast error_detected message\n"); if (state == pci_channel_io_frozen) { pci_walk_bus(bus, report_frozen_detected, &status); - status = reset_link(dev); - if (status != PCI_ERS_RESULT_RECOVERED) { + /* + * After resetting the link using reset_link() call, the + * possible value of error status is either + * PCI_ERS_RESULT_DISCONNECT (failure case) or + * PCI_ERS_RESULT_NEED_RESET (success case). + * So ignore the return value of report_error_detected() + * call for fatal errors. Instead use + * PCI_ERS_RESULT_NEED_RESET as initial status value. + * + * Ignoring the status return value of report_error_detected() + * call will also help in case of EDR mode based error + * recovery. In EDR mode AER and DPC Capabilities are owned by + * firmware and hence report_error_detected() call will possibly + * return PCI_ERS_RESULT_NO_AER_DRIVER. So if we don't ignore + * the return value of report_error_detected() then + * pcie_do_recovery() would report incorrect status after + * successful recovery. Ignoring PCI_ERS_RESULT_NO_AER_DRIVER + * in non EDR case should not have any functional impact. + */ + status = PCI_ERS_RESULT_NEED_RESET; + if (reset_link(dev) != PCI_ERS_RESULT_RECOVERED) { + status = PCI_ERS_RESULT_DISCONNECT; pci_warn(dev, "link reset failed\n"); goto failed; } -- 2.17.1
