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authorBodong Wang <bodong@mellanox.com>2017-04-13 01:51:40 +0300
committerBjorn Helgaas <bhelgaas@google.com>2017-04-20 08:53:51 -0500
commit0e7df22401a3dfd403b26dea62dd00e0598b538b (patch)
tree484063ef8f232bf8d51d998a1331513a9f2c8b5a /Documentation
parentf65fd1aa4f9881d5540192d11f7b8ed2fec936db (diff)
PCI: Add sysfs sriov_drivers_autoprobe to control VF driver binding
Sometimes it is not desirable to bind SR-IOV VFs to drivers. This can save host side resource usage by VF instances that will be assigned to VMs. Add a new PCI sysfs interface "sriov_drivers_autoprobe" to control that from the PF. To modify it, echo 0/n/N (disable probe) or 1/y/Y (enable probe) to: /sys/bus/pci/devices/<DOMAIN:BUS:DEVICE.FUNCTION>/sriov_drivers_autoprobe Note that this must be done before enabling VFs. The change will not take effect if VFs are already enabled. Simply, one can disable VFs by setting sriov_numvfs to 0, choose whether to probe or not, and then re-enable the VFs by restoring sriov_numvfs. [bhelgaas: changelog, ABI doc] Signed-off-by: Bodong Wang <bodong@mellanox.com> Signed-off-by: Eli Cohen <eli@mellanox.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Gavin Shan <gwshan@linux.vnet.ibm.com> Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/ABI/testing/sysfs-bus-pci22
-rw-r--r--Documentation/PCI/pci-iov-howto.txt12
2 files changed, 34 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
index 5a1732b78707..b728f700340d 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci
+++ b/Documentation/ABI/testing/sysfs-bus-pci
@@ -301,3 +301,25 @@ Contact: Emil Velikov <emil.l.velikov@gmail.com>
Description:
This file contains the revision field of the the PCI device.
The value comes from device config space. The file is read only.
+
+What: /sys/bus/pci/devices/.../sriov_drivers_autoprobe
+Date: April 2017
+Contact: Bodong Wang<bodong@mellanox.com>
+Description:
+ This file is associated with the PF of a device that
+ supports SR-IOV. It determines whether newly-enabled VFs
+ are immediately bound to a driver. It initially contains
+ 1, which means the kernel automatically binds VFs to a
+ compatible driver immediately after they are enabled. If
+ an application writes 0 to the file before enabling VFs,
+ the kernel will not bind VFs to a driver.
+
+ A typical use case is to write 0 to this file, then enable
+ VFs, then assign the newly-created VFs to virtual machines.
+ Note that changing this file does not affect already-
+ enabled VFs. In this scenario, the user must first disable
+ the VFs, write 0 to sriov_drivers_autoprobe, then re-enable
+ the VFs.
+
+ This is similar to /sys/bus/pci/drivers_autoprobe, but
+ affects only the VFs associated with a specific PF.
diff --git a/Documentation/PCI/pci-iov-howto.txt b/Documentation/PCI/pci-iov-howto.txt
index 2d91ae251982..d2a84151e99c 100644
--- a/Documentation/PCI/pci-iov-howto.txt
+++ b/Documentation/PCI/pci-iov-howto.txt
@@ -68,6 +68,18 @@ To disable SR-IOV capability:
echo 0 > \
/sys/bus/pci/devices/<DOMAIN:BUS:DEVICE.FUNCTION>/sriov_numvfs
+To enable auto probing VFs by a compatible driver on the host, run
+command below before enabling SR-IOV capabilities. This is the
+default behavior.
+ echo 1 > \
+ /sys/bus/pci/devices/<DOMAIN:BUS:DEVICE.FUNCTION>/sriov_drivers_autoprobe
+
+To disable auto probing VFs by a compatible driver on the host, run
+command below before enabling SR-IOV capabilities. Updating this
+entry will not affect VFs which are already probed.
+ echo 0 > \
+ /sys/bus/pci/devices/<DOMAIN:BUS:DEVICE.FUNCTION>/sriov_drivers_autoprobe
+
3.2 Usage example
Following piece of code illustrates the usage of the SR-IOV API.