Re: [PATCH v9 10/15] PCI/ERR: Limit AER resets in pcie_do_recovery()

Sean V Kelley
2020-10-16T17:36:32Z

On 16 Oct 2020, at 10:22, Bjorn Helgaas wrote:

> On Thu, Oct 15, 2020 at 05:11:08PM -0700, Sean V Kelley wrote:
>> From: Sean V Kelley <sean.v.kelley@intel.com>
>>
>> In some cases a bridge may not exist as the hardware controlling may
>> be
>> handled only by firmware and so is not visible to the OS. This
>> scenario is
>> also possible in future use cases involving non-native use of RCECs
>> by
>> firmware.
>>
>> Explicitly apply conditional logic around these resets by limiting
>> them to
>> Root Ports and Downstream Ports.
>>
>> Link:
>> https://lore.kernel.org/r/20201002184735.1229220-8-seanvk.dev@oregontracks.org
>> Signed-off-by: Sean V Kelley <sean.v.kelley@intel.com>
>> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
>> Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
>> ---
>> drivers/pci/pcie/err.c | 31 +++++++++++++++++++++++++------
>> 1 file changed, 25 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
>> index 8b53aecdb43d..7883c9791562 100644
>> --- a/drivers/pci/pcie/err.c
>> +++ b/drivers/pci/pcie/err.c
>> @@ -148,13 +148,17 @@ static int report_resume(struct pci_dev *dev,
>> void *data)
>>
>> /**
>> * pci_walk_bridge - walk bridges potentially AER affected
>> - * @bridge: bridge which may be a Port
>> + * @bridge: bridge which may be a Port, an RCEC with associated
>> RCiEPs,
>> + * or an RCiEP associated with an RCEC
>> * @cb: callback to be called for each device found
>> * @userdata: arbitrary pointer to be passed to callback
>> *
>> * If the device provided is a bridge, walk the subordinate bus,
>> including
>> * any bridged devices on buses under this bus. Call the provided
>> callback
>> * on each device found.
>> + *
>> + * If the device provided has no subordinate bus, call the callback
>> on the
>> + * device itself.
>> */
>> static void pci_walk_bridge(struct pci_dev *bridge,
>> int (*cb)(struct pci_dev *, void *),
>> @@ -162,6 +166,8 @@ static void pci_walk_bridge(struct pci_dev
>> *bridge,
>> {
>> if (bridge->subordinate)
>> pci_walk_bus(bridge->subordinate, cb, userdata);
>> + else
>> + cb(bridge, userdata);
>
> Looks like *this* is the patch where the "no subordinate bus" case
> becomes possible? If you agree, I can just move the test here, no
> need to repost.

Agree, this is the patch that the check is needed as we are opening
things up for walking RC_ECs and RC_ENDs as below.

Sean

>
>> }
>>
>> pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
>> @@ -174,10 +180,13 @@ pci_ers_result_t pcie_do_recovery(struct
>> pci_dev *dev,
>>
>> /*
>> * Error recovery runs on all subordinates of the bridge. If the
>> - * bridge detected the error, it is cleared at the end.
>> + * bridge detected the error, it is cleared at the end. For RCiEPs
>> + * we should reset just the RCiEP itself.
>> */
>> if (type == PCI_EXP_TYPE_ROOT_PORT ||
>> - type == PCI_EXP_TYPE_DOWNSTREAM)
>> + type == PCI_EXP_TYPE_DOWNSTREAM ||
>> + type == PCI_EXP_TYPE_RC_EC ||
>> + type == PCI_EXP_TYPE_RC_END)
>> bridge = dev;
>> else
>> bridge = pci_upstream_bridge(dev);
>> @@ -185,6 +194,12 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev
>> *dev,
>> pci_dbg(bridge, "broadcast error_detected message\n");
>> if (state == pci_channel_io_frozen) {
>> pci_walk_bridge(bridge, report_frozen_detected, &status);
>> + if (type == PCI_EXP_TYPE_RC_END) {
>> + pci_warn(dev, "subordinate device reset not possible for
>> RCiEP\n");
>> + status = PCI_ERS_RESULT_NONE;
>> + goto failed;
>> + }
>> +
>> status = reset_subordinates(bridge);
>> if (status != PCI_ERS_RESULT_RECOVERED) {
>> pci_warn(bridge, "subordinate device reset failed\n");
>> @@ -217,9 +232,13 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev
>> *dev,
>> pci_dbg(bridge, "broadcast resume message\n");
>> pci_walk_bridge(bridge, report_resume, &status);
>>
>> - if (pcie_aer_is_native(bridge))
>> - pcie_clear_device_status(bridge);
>> - pci_aer_clear_nonfatal_status(bridge);
>> + if (type == PCI_EXP_TYPE_ROOT_PORT ||
>> + type == PCI_EXP_TYPE_DOWNSTREAM ||
>> + type == PCI_EXP_TYPE_RC_EC) {
>> + if (pcie_aer_is_native(bridge))
>> + pcie_clear_device_status(bridge);
>> + pci_aer_clear_nonfatal_status(bridge);
>> + }
>> pci_info(bridge, "device recovery successful\n");
>> return status;
>>
>> --
>> 2.28.0
>>