From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Date: Mon, 18 Apr 2022 15:02:37 +0000
Subject: PCI/AER: Clear MULTI_ERR_COR/UNCOR_RCV bits
Git-commit: 203926da2bff8e172200a2f11c758987af112d4a
Patch-mainline: 5.19-rc1
References: git-fixes

When a Root Port or Root Complex Event Collector receives an error Message
e.g., ERR_COR, it sets PCI_ERR_ROOT_COR_RCV in the Root Error Status
register and logs the Requester ID in the Error Source Identification
register.  If it receives a second ERR_COR Message before software clears
PCI_ERR_ROOT_COR_RCV, hardware sets PCI_ERR_ROOT_MULTI_COR_RCV and the
Requester ID is lost.

In the following scenario, PCI_ERR_ROOT_MULTI_COR_RCV was never cleared:

  - hardware receives ERR_COR message
  - hardware sets PCI_ERR_ROOT_COR_RCV
  - aer_irq() entered
  - aer_irq(): status = pci_read_config_dword(PCI_ERR_ROOT_STATUS)
  - aer_irq(): now status == PCI_ERR_ROOT_COR_RCV
  - hardware receives second ERR_COR message
  - hardware sets PCI_ERR_ROOT_MULTI_COR_RCV
  - aer_irq(): pci_write_config_dword(PCI_ERR_ROOT_STATUS, status)
  - PCI_ERR_ROOT_COR_RCV is cleared; PCI_ERR_ROOT_MULTI_COR_RCV is set
  - aer_irq() entered again
  - aer_irq(): status = pci_read_config_dword(PCI_ERR_ROOT_STATUS)
  - aer_irq(): now status == PCI_ERR_ROOT_MULTI_COR_RCV
  - aer_irq() exits because PCI_ERR_ROOT_COR_RCV not set
  - PCI_ERR_ROOT_MULTI_COR_RCV is still set

The same problem occurred with ERR_NONFATAL/ERR_FATAL Messages and
PCI_ERR_ROOT_UNCOR_RCV and PCI_ERR_ROOT_MULTI_UNCOR_RCV.

Fix the problem by queueing an AER event and clearing the Root Error Status
bits when any of these bits are set:

  PCI_ERR_ROOT_COR_RCV
  PCI_ERR_ROOT_UNCOR_RCV
  PCI_ERR_ROOT_MULTI_COR_RCV
  PCI_ERR_ROOT_MULTI_UNCOR_RCV

See the bugzilla link for details from Eric about how to reproduce this
problem.

[bhelgaas: commit log, move repro details to bugzilla]
Fixes: e167bfcaa4cd ("PCI: aerdrv: remove magical ROOT_ERR_STATUS_MASKS")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=215992
Link: https://lore.kernel.org/r/20220418150237.1021519-1-sathyanarayanan.kuppuswamy@linux.intel.com
Reported-by: Eric Badger <ebadger@purestorage.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 drivers/pci/pcie/aer/aerdrv.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/drivers/pci/pcie/aer/aerdrv.c
+++ b/drivers/pci/pcie/aer/aerdrv.c
@@ -45,6 +45,11 @@ static struct pcie_port_service_driver a
 	.reset_link	= aer_root_reset,
 };
 
+#define AER_ERR_STATUS_MASK		(PCI_ERR_ROOT_UNCOR_RCV |	\
+					PCI_ERR_ROOT_COR_RCV |		\
+					PCI_ERR_ROOT_MULTI_COR_RCV |	\
+					PCI_ERR_ROOT_MULTI_UNCOR_RCV)
+
 static int pcie_aer_disable;
 
 void pci_no_aer(void)
@@ -188,7 +193,7 @@ irqreturn_t aer_irq(int irq, void *conte
 
 	/* Read error status */
 	pci_read_config_dword(pdev->port, pos + PCI_ERR_ROOT_STATUS, &status);
-	if (!(status & (PCI_ERR_ROOT_UNCOR_RCV|PCI_ERR_ROOT_COR_RCV))) {
+	if (!(status & AER_ERR_STATUS_MASK)) {
 		spin_unlock_irqrestore(&rpc->e_lock, flags);
 		return IRQ_NONE;
 	}