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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Eric Badger <ebadger@purestorage.com>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@linux.intel.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Ashok Raj <ashok.raj@intel.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 460/667] PCI/AER: Clear MULTI_ERR_COR/UNCOR_RCV bits
Date:   Tue,  7 Jun 2022 19:02:05 +0200
Message-Id: <20220607164948.508095839@linuxfoundation.org>
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From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>

[ Upstream commit 203926da2bff8e172200a2f11c758987af112d4a ]

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: Sasha Levin <sashal@kernel.org>
---
 drivers/pci/pcie/aer.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index 9784fdcf3006..80fe3e83c9f5 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c
@@ -101,6 +101,11 @@ struct aer_stats {
 #define ERR_COR_ID(d)			(d & 0xffff)
 #define ERR_UNCOR_ID(d)			(d >> 16)
 
+#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;
 static pci_ers_result_t aer_root_reset(struct pci_dev *dev);
 
@@ -1196,7 +1201,7 @@ static irqreturn_t aer_irq(int irq, void *context)
 	struct aer_err_source e_src = {};
 
 	pci_read_config_dword(rp, aer + PCI_ERR_ROOT_STATUS, &e_src.status);
-	if (!(e_src.status & (PCI_ERR_ROOT_UNCOR_RCV|PCI_ERR_ROOT_COR_RCV)))
+	if (!(e_src.status & AER_ERR_STATUS_MASK))
 		return IRQ_NONE;
 
 	pci_read_config_dword(rp, aer + PCI_ERR_ROOT_ERR_SRC, &e_src.id);
-- 
2.35.1