Hi Bjorn, > On Nov 23, 2020, at 3:28 PM, Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > > On Fri, Nov 20, 2020 at 04:10:31PM -0800, Sean V Kelley wrote: >> 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. > > Can you help me understand this? The subject says "Limit AER resets" > and here you say "limit them to RPs and DPs", but it's not completely > obvious how the resets are being limited, i.e., the patch doesn't add > anything like: > > + if (type == PCI_EXP_TYPE_ROOT_PORT || > + type == PCI_EXP_TYPE_DOWNSTREAM) > reset_subordinates(bridge); > > It *does* add checks around pcie_clear_device_status(), but that also > includes RC_EC. And that's not a reset, so I don't think that's > explicitly mentioned in the commit log. The subject should have referred to the clearing of the device status rather than resets. It originally came from this simpler patch in which I made use of reset instead of clear: https://lore.kernel.org/linux-pci/20201002184735.1229220-8-seanvk.dev@xxxxxxxxxxxxxxxx/ So a rephrase of clearing in place of resets would be more appropriate. Then we added the notion of bridges…below > > Also see the question below. > >> Link: https://lore.kernel.org/r/20201002184735.1229220-8-seanvk.dev@xxxxxxxxxxxxxxxx >> Signed-off-by: Sean V Kelley <sean.v.kelley@xxxxxxxxx> >> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> >> Acked-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> >> --- >> 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); >> } >> >> 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); > > This is hard to understand because "type" is from "dev", but "bridge" > is not necessarily the same device. Should it be this? > > type = pci_pcie_type(bridge); > if (type == PCI_EXP_TYPE_ROOT_PORT || > ...) Correct, it would be better if the type was based on the ‘bridge’. Thanks, Sean > >> + } >> pci_info(bridge, "device recovery successful\n"); >> return status; >> >> -- >> 2.29.2
