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[PATCH v5 0/3] Add new PCI_DEV_FLAGS_NO_RELAXED_ORDERING flag

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  [PATCH v5 0/3] Add new PCI_DEV_FLAGS_NO_RELAXED_ORDERING flag Ding Tianhong <dingtianhong@huawei.com> - 2017-06-19 09:00 +0200
    [PATCH v5 1/3] PCI: Add new PCIe Fabric End Node flag, PCI_DEV_FLAGS_NO_RELAXED_ORDERING Ding Tianhong <dingtianhong@huawei.com> - 2017-06-19 09:00 +0200

#1668841 — [PATCH v5 0/3] Add new PCI_DEV_FLAGS_NO_RELAXED_ORDERING flag

Some devices have problems with Transaction Layer Packets with the Relaxed
Ordering Attribute set.  This patch set adds a new PCIe Device Flag,
PCI_DEV_FLAGS_NO_RELAXED_ORDERING, a set of PCI Quirks to catch some known
devices with Relaxed Ordering issues, and a use of this new flag by the
cxgb4 driver to avoid using Relaxed Ordering with problematic Root Complex
Ports.

It's been years since I've submitted kernel.org patches, I appolgise for the
almost certain submission errors.

v2: Alexander point out that the v1 was only a part of the whole solution,
    some platform which has some issues could use the new flag to indicate
    that it is not safe to enable relaxed ordering attribute, then we need
    to clear the relaxed ordering enable bits in the PCI configuration when
    initializing the device. So add a new second patch to modify the PCI
    initialization code to clear the relaxed ordering enable bit in the
    event that the root complex doesn't want relaxed ordering enabled.

    The third patch was base on the v1's second patch and only be changed
    to query the relaxed ordering enable bit in the PCI configuration space
    to allow the Chelsio NIC to send TLPs with the relaxed ordering attributes
    set.

    This version didn't plan to drop the defines for Intel Drivers to use the
    new checking way to enable relaxed ordering because it is not the hardest
    part of the moment, we could fix it in next patchset when this patches
    reach the goal.  

v3: Redesigned the logic for pci_configure_relaxed_ordering when configuration,
    If a PCIe device didn't enable the relaxed ordering attribute default,
    we should not do anything in the PCIe configuration, otherwise we
    should check if any of the devices above us do not support relaxed
    ordering by the PCI_DEV_FLAGS_NO_RELAXED_ORDERING flag, then base on
    the result if we get a return that indicate that the relaxed ordering
    is not supported we should update our device to disable relaxed ordering
    in configuration space. If the device above us doesn't exist or isn't
    the PCIe device, we shouldn't do anything and skip updating relaxed ordering
    because we are probably running in a guest.

v4: Rename the functions pcie_get_relaxed_ordering and pcie_disable_relaxed_ordering
    according John's suggestion, and modify the description, use the true/false
    as the return value.

    We shouldn't enable relaxed ordering attribute by the setting in the root
    complex configuration space for PCIe device, so fix it for cxgb4.

    Fix some format issues.

v5: Removed the unnecessary code for some function which only return the bool
    value, and add the check for VF device.

    Make this patch set base on 4.12-rc5.

Casey Leedom (2):
  PCI: Add new PCIe Fabric End Node flag,
    PCI_DEV_FLAGS_NO_RELAXED_ORDERING
  net/cxgb4: Use new PCI_DEV_FLAGS_NO_RELAXED_ORDERING flag

Ding Tianhong (1):
  PCI: Enable PCIe Relaxed Ordering if supported

 drivers/net/ethernet/chelsio/cxgb4/cxgb4.h      |  1 +
 drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c | 17 ++++++++++
 drivers/net/ethernet/chelsio/cxgb4/sge.c        |  5 +--
 drivers/pci/pci.c                               | 32 +++++++++++++++++++
 drivers/pci/probe.c                             | 41 +++++++++++++++++++++++++
 drivers/pci/quirks.c                            | 38 +++++++++++++++++++++++
 include/linux/pci.h                             |  4 +++
 7 files changed, 136 insertions(+), 2 deletions(-)

-- 
1.9.0

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#1668842 — [PATCH v5 1/3] PCI: Add new PCIe Fabric End Node flag, PCI_DEV_FLAGS_NO_RELAXED_ORDERING

From: Casey Leedom <leedom@chelsio.com>

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.

Signed-off-by: Casey Leedom <leedom@chelsio.com>
Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
---
 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 085fb78..58bdd23 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -3999,6 +3999,44 @@ 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(PCI_VENDOR_ID_INTEL, 0x6f02, PCI_CLASS_NOT_DEFINED, 8,
+			      quirk_relaxedordering_disable);
+DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_INTEL, 0x6f04, PCI_CLASS_NOT_DEFINED, 8,
+			      quirk_relaxedordering_disable);
+DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_INTEL, 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(PCI_VENDOR_ID_AMD, 0x1a00, PCI_CLASS_NOT_DEFINED, 8,
+			      quirk_relaxedordering_disable);
+DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_AMD, 0x1a01, PCI_CLASS_NOT_DEFINED, 8,
+			      quirk_relaxedordering_disable);
+DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_AMD, 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 8039f9f..ce77690 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -188,6 +188,8 @@ enum pci_dev_flags {
 	 * the direct_complete optimization.
 	 */
 	PCI_DEV_FLAGS_NEEDS_RESUME = (__force pci_dev_flags_t) (1 << 11),
+	/* Don't use Relaxed Ordering for TLPs directed at this device */
+	PCI_DEV_FLAGS_NO_RELAXED_ORDERING = (__force pci_dev_flags_t) (1 << 12),
 };
 
 enum pci_irq_reroute_variant {
-- 
1.9.0

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