Re: [PATCH v10 13/16] PCI/RCEC: Add RCiEP's linked RCEC to AER/ERR

From: Sean V Kelley
Date: Thu Nov 05 2020 - 19:40:35 EST

On 5 Nov 2020, at 16:14, Sean V Kelley wrote:

From: Qiuxu Zhuo <qiuxu.zhuo@xxxxxxxxx>

When attempting error recovery for an RCiEP associated with an RCEC device,
there needs to be a way to update the Root Error Status, the Uncorrectable
Error Status and the Uncorrectable Error Severity of the parent RCEC. In
some non-native cases in which there is no OS-visible device associated
with the RCiEP, there is nothing to act upon as the firmware is acting
before the OS.

Add handling for the linked RCEC in AER/ERR while taking into account
non-native cases.

Co-developed-by: Sean V Kelley <sean.v.kelley@xxxxxxxxx>
Link: https://lore.kernel.org/r/20201002184735.1229220-12-seanvk.dev@xxxxxxxxxxxxxxxx
Signed-off-by: Sean V Kelley <sean.v.kelley@xxxxxxxxx>
Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@xxxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
---
drivers/pci/pcie/aer.c | 35 +++++++++++++++++++++++++++--------
drivers/pci/pcie/err.c | 20 ++++++++++----------
2 files changed, 37 insertions(+), 18 deletions(-)

diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index 4ab379fa1506..3498af81d240 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c
@@ -1357,29 +1357,48 @@ static int aer_probe(struct pcie_device *dev)
*/
static pci_ers_result_t aer_root_reset(struct pci_dev *dev)
{
+ int type = pci_pcie_type(dev);
int aer = dev->aer_cap;
+ struct pci_dev *root;
int rc = 0;
u32 reg32;

+ if (type == PCI_EXP_TYPE_RC_END)
+ /*
+ * The reset should only clear the Root Error Status
+ * of the RCEC. Only perform this for the
+ * native case, i.e., an RCEC is present.
+ */
+ root = dev->rcec;
+ else
+ root = dev;
+
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);
+ pci_read_config_dword(root, aer + PCI_ERR_ROOT_COMMAND, &reg32);
reg32 &= ~ROOT_PORT_INTR_ON_MESG_MASK;
- pci_write_config_dword(dev, aer + PCI_ERR_ROOT_COMMAND, reg32);
+ pci_write_config_dword(root, aer + PCI_ERR_ROOT_COMMAND, reg32);
}

- rc = pci_bus_error_reset(dev);
- pci_info(dev, "Root Port link has been reset (%d)\n", rc);
+ if (type == PCI_EXP_TYPE_RC_EC || type == PCI_EXP_TYPE_RC_END) {
+ if (pcie_has_flr(root)) {
+ rc = pcie_flr(root);
+ pci_info(dev, "has been reset (%d)\n", rc);
+ }
+ } else {
+ rc = pci_bus_error_reset(root);
+ pci_info(dev, "Root Port link has been reset (%d)\n", rc);
+ }

So this needs to change as I didn’t use the aer = dev->aer_cap from before
because I’m checking explicitly for pcie_aer_is_native(). However, we still
have the scenario of non-native and root = dev->rcec = NULL. Secondly, for the flr, that
should be happening on the dev and that should trump use of the root var anyway.

So I would change it to: (replacing root with dev)

+ if (type == PCI_EXP_TYPE_RC_EC || type == PCI_EXP_TYPE_RC_END) {
+ if (pcie_has_flr(dev)) {
+ rc = pcie_flr(dev);
+ pci_info(dev, "has been reset (%d)\n", rc);
+ }
+ } else {
+ rc = pci_bus_error_reset(dev);
+ pci_info(dev, "Root Port link has been reset (%d)\n", rc);
+ }

Thanks,

Sean



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);
+ pci_read_config_dword(root, aer + PCI_ERR_ROOT_STATUS, &reg32);
+ pci_write_config_dword(root, 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);
+ pci_read_config_dword(root, aer + PCI_ERR_ROOT_COMMAND, &reg32);
reg32 |= ROOT_PORT_INTR_ON_MESG_MASK;
- pci_write_config_dword(dev, aer + PCI_ERR_ROOT_COMMAND, reg32);
+ pci_write_config_dword(root, aer + PCI_ERR_ROOT_COMMAND, reg32);
}

return rc ? PCI_ERS_RESULT_DISCONNECT : PCI_ERS_RESULT_RECOVERED;
diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
index 7883c9791562..cbc5abfe767b 100644
--- a/drivers/pci/pcie/err.c
+++ b/drivers/pci/pcie/err.c
@@ -148,10 +148,10 @@ 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, 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
+ * @bridge bridge which may be an RCEC with associated RCiEPs,
+ * or a Port.
+ * @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
@@ -164,8 +164,14 @@ static void pci_walk_bridge(struct pci_dev *bridge,
int (*cb)(struct pci_dev *, void *),
void *userdata)
{
+ /*
+ * In a non-native case where there is no OS-visible reporting
+ * device the bridge will be NULL, i.e., no RCEC, no Downstream Port.
+ */
if (bridge->subordinate)
pci_walk_bus(bridge->subordinate, cb, userdata);
+ else if (bridge->rcec)
+ cb(bridge->rcec, userdata);
else
cb(bridge, userdata);
}
@@ -194,12 +200,6 @@ 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");
--
2.29.2