netdev - [PATCH 1/2] PCI: Add new PCIe Fabric End Node flag, PCI_DEV_FLAGS_NO_RELAXED

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Date:   Mon,  1 May 2017 16:13:50 -0700
From:   Casey Leedom <leedom@...lsio.com>
To:     Bjorn Helgaas <helgaas@...nel.org>, leedom@...il.com
Cc:     Casey Leedom <leedom@...lsio.com>,
        Michael Werner <werner@...lsio.com>,
        Ganesh Goudar <ganeshgr@...lsio.com>,
        Arjun V <arjun@...lsio.com>,
        David Miller <davem@...emloft.com>,
        Asit K Mallick <asit.k.mallick@...el.com>,
        Patrick J Cramer <patrick.j.cramer@...el.com>,
        Ashok Raj <ashok.raj@...el.com>,
        Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>,
        Bob Shaw <Bob.Shaw@....com>, h <l.stach@...gutronix.de>,
        Alexander Duyck <alexander.duyck@...il.com>,
        Ding Tianhong <dingtianhong@...wei.com>,
        Mark Rutland <mark.rutland@....com>,
        Amir Ancel <amira@...lanox.com>,
        Gabriele Paoloni <gabriele.paoloni@...wei.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        LinuxArm <linuxarm@...wei.com>,
        David Laight <David.Laight@...lab.com>,
        jeffrey.t.kirsher@...el.com, netdev@...r.kernel.org,
        Robin Murphy <robin.murphy@....com>, davem@...emloft.net,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH 1/2] PCI: Add new PCIe Fabric End Node flag, PCI_DEV_FLAGS_NO_RELAXED_ORDERING

The new flag PCI_DEV_FLAGS_NO_RELAXED_ORDERING indicates that the Relaxed
Ordering Attribute should not be used on Transaction Layer Packets destined
for the PCIe End Node so flagged.  Initially flagged this way are Intel
E5-26xx Root Complex Ports which suffer from a Flow Control Credit
Performance Problem and AMD A1100 ARM ("SEATTLE") Root Complex Ports which
don't obey PCIe 3.0 ordering rules which can lead to Data Corruption.
---
 drivers/pci/quirks.c | 38 ++++++++++++++++++++++++++++++++++++++
 include/linux/pci.h  |  2 ++
 2 files changed, 40 insertions(+)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index f754453..4ae78b3 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -3979,6 +3979,44 @@ static void quirk_tw686x_class(struct pci_dev *pdev)
 			      quirk_tw686x_class);
 
 /*
+ * Some devices have problems with Transaction Layer Packets with the Relaxed
+ * Ordering Attribute set.  Such devices should mark themselves and other
+ * Device Drivers should check before sending TLPs with RO set.
+ */
+static void quirk_relaxedordering_disable(struct pci_dev *dev)
+{
+	dev->dev_flags |= PCI_DEV_FLAGS_NO_RELAXED_ORDERING;
+}
+
+/*
+ * Intel E5-26xx Root Complex has a Flow Control Credit issue which can
+ * cause performance problems with Upstream Transaction Layer Packets with
+ * Relaxed Ordering set.
+ */
+DECLARE_PCI_FIXUP_CLASS_EARLY(0x8086, 0x6f02, PCI_CLASS_NOT_DEFINED, 8,
+			      quirk_relaxedordering_disable);
+DECLARE_PCI_FIXUP_CLASS_EARLY(0x8086, 0x6f04, PCI_CLASS_NOT_DEFINED, 8,
+			      quirk_relaxedordering_disable);
+DECLARE_PCI_FIXUP_CLASS_EARLY(0x8086, 0x6f08, PCI_CLASS_NOT_DEFINED, 8,
+			      quirk_relaxedordering_disable);
+
+/*
+ * The AMD ARM A1100 (AKA "SEATTLE") SoC has a bug in its PCIe Root Complex
+ * where Upstream Transaction Layer Packets with the Relaxed Ordering
+ * Attribute clear are allowed to bypass earlier TLPs with Relaxed Ordering
+ * set.  This is a violation of the PCIe 3.0 Transaction Ordering Rules
+ * outlined in Section 2.4.1 (PCI Express(r) Base Specification Revision 3.0
+ * November 10, 2010).  As a result, on this platform we can't use Relaxed
+ * Ordering for Upstream TLPs.
+ */
+DECLARE_PCI_FIXUP_CLASS_EARLY(0x1022, 0x1a00, PCI_CLASS_NOT_DEFINED, 8,
+			      quirk_relaxedordering_disable);
+DECLARE_PCI_FIXUP_CLASS_EARLY(0x1022, 0x1a01, PCI_CLASS_NOT_DEFINED, 8,
+			      quirk_relaxedordering_disable);
+DECLARE_PCI_FIXUP_CLASS_EARLY(0x1022, 0x1a02, PCI_CLASS_NOT_DEFINED, 8,
+			      quirk_relaxedordering_disable);
+
+/*
  * Per PCIe r3.0, sec 2.2.9, "Completion headers must supply the same
  * values for the Attribute as were supplied in the header of the
  * corresponding Request, except as explicitly allowed when IDO is used."
diff --git a/include/linux/pci.h b/include/linux/pci.h
index eb3da1a..6764f66 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -178,6 +178,8 @@ enum pci_dev_flags {
 	PCI_DEV_FLAGS_NO_PM_RESET = (__force pci_dev_flags_t) (1 << 7),
 	/* Get VPD from function 0 VPD */
 	PCI_DEV_FLAGS_VPD_REF_F0 = (__force pci_dev_flags_t) (1 << 8),
+	/* Don't use Relaxed Ordering for TLPs directed at this device */
+	PCI_DEV_FLAGS_NO_RELAXED_ORDERING = (__force pci_dev_flags_t) (1 << 9),
 };
 
 enum pci_irq_reroute_variant {
-- 
1.9.1