linux-kernel - [PATCH] PCI/AER: Do not clear AER bits if we don't own AER

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Date:   Tue, 17 Jul 2018 10:31:23 -0500
From:   Alexandru Gagniuc <mr.nuke.me@...il.com>
To:     bhelgaas@...gle.com, keith.busch@...el.com
Cc:     alex_gagniuc@...lteam.com, austin_bolen@...l.com,
        shyam_iyer@...l.com, Alexandru Gagniuc <mr.nuke.me@...il.com>,
        Frederick Lawler <fred@...dlawl.com>,
        Oza Pawandeep <poza@...eaurora.org>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] PCI/AER: Do not clear AER bits if we don't own AER

When we don't own AER, we shouldn't touch the AER error bits. This
happens unconditionally on device probe(). Clearing AER bits
willy-nilly might cause firmware to miss errors. Instead
these bits should get cleared by FFS, or via ACPI _HPX method.

This race is mostly of theoretical significance, as it is not easy to
reasonably demonstrate it in testing.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@...il.com>
---
 drivers/pci/pcie/aer.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index a2e88386af28..18037a2a8231 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c
@@ -383,6 +383,9 @@ int pci_cleanup_aer_error_status_regs(struct pci_dev *dev)
 	if (!pci_is_pcie(dev))
 		return -ENODEV;
 
+	if (pcie_aer_get_firmware_first(dev))
+		return -EIO;
+
 	pos = dev->aer_cap;
 	if (!pos)
 		return -EIO;
-- 
2.14.3