From: Keith Busch <keith.busch@intel.com>
To: Bjorn Helgaas <helgaas@kernel.org>, linux-pci@vger.kernel.org
Cc: Alex Williamson <alex.williamson@redhat.com>,
Alexandru Gagniuc <alex_gagniuc@dellteam.com>,
Keith Busch <keith.busch@intel.com>
Subject: [PATCHv2] PCI/LINK: Add Kconfig option (default off)
Date: Wed, 1 May 2019 08:29:42 -0600
Message-ID: <20190501142942.26972-1-keith.busch@intel.com> (raw)
e8303bb7a75c ("PCI/LINK: Report degraded links via link bandwidth
notification") added dmesg logging whenever a link changes speed or width
to a state that is considered degraded. Unfortunately, it cannot
differentiate signal integrity-related link changes from those
intentionally initiated by an endpoint driver, including drivers that may
live in userspace or VMs when making use of vfio-pci. Some GPU drivers
actively manage the link state to save power, which generates a stream of
messages like this:
vfio-pci 0000:07:00.0: 32.000 Gb/s available PCIe bandwidth, limited by 2.5 GT/s x16 link at 0000:00:02.0 (capable of 64.000 Gb/s with 5 GT/s x16 link)
Since we can't distinguish the intentional changes from the signal
integrity issues, leave the reporting turned off by default. Add a Kconfig
option to turn it on if desired.
Fixes: e8303bb7a75c ("PCI/LINK: Report degraded links via link bandwidth notification")
Signed-off-by: Keith Busch <keith.busch@intel.com>
---
drivers/pci/pcie/Kconfig | 8 ++++++++
drivers/pci/pcie/Makefile | 2 +-
drivers/pci/pcie/portdrv.h | 4 ++++
3 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/pcie/Kconfig b/drivers/pci/pcie/Kconfig
index 5cbdbca904ac..a70efdffe647 100644
--- a/drivers/pci/pcie/Kconfig
+++ b/drivers/pci/pcie/Kconfig
@@ -142,3 +142,11 @@ config PCIE_PTM
This is only useful if you have devices that support PTM, but it
is safe to enable even if you don't.
+
+config PCIE_BW
+ bool "PCI Express Bandwidth Change Notification"
+ depends on PCIEPORTBUS
+ help
+ This enables PCI Express Bandwidth Change Notification. If
+ you know link width or rate changes occur only to correct
+ unreliable links, you may answer Y.
diff --git a/drivers/pci/pcie/Makefile b/drivers/pci/pcie/Makefile
index f1d7bc1e5efa..efb9d2e71e9e 100644
--- a/drivers/pci/pcie/Makefile
+++ b/drivers/pci/pcie/Makefile
@@ -3,7 +3,6 @@
# Makefile for PCI Express features and port driver
pcieportdrv-y := portdrv_core.o portdrv_pci.o err.o
-pcieportdrv-y += bw_notification.o
obj-$(CONFIG_PCIEPORTBUS) += pcieportdrv.o
@@ -13,3 +12,4 @@ obj-$(CONFIG_PCIEAER_INJECT) += aer_inject.o
obj-$(CONFIG_PCIE_PME) += pme.o
obj-$(CONFIG_PCIE_DPC) += dpc.o
obj-$(CONFIG_PCIE_PTM) += ptm.o
+obj-$(CONFIG_PCIE_BW) += bw_notification.o
diff --git a/drivers/pci/pcie/portdrv.h b/drivers/pci/pcie/portdrv.h
index 1d50dc58ac40..944827a8c7d3 100644
--- a/drivers/pci/pcie/portdrv.h
+++ b/drivers/pci/pcie/portdrv.h
@@ -49,7 +49,11 @@ int pcie_dpc_init(void);
static inline int pcie_dpc_init(void) { return 0; }
#endif
+#ifdef CONFIG_PCIE_BW
int pcie_bandwidth_notification_init(void);
+#else
+static inline int pcie_bandwidth_notification_init(void) { return 0; }
+#endif
/* Port Type */
#define PCIE_ANY_PORT (~0)
--
2.14.4
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Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-01 14:29 Keith Busch [this message]
2019-05-01 18:01 ` Bjorn Helgaas
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