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

Bjorn Helgaas
2020-10-16T17:22:15Z

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.

> }
>
> 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
>