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PCI: Add sysfs sriov_drivers_autoprobe to control VF driver binding

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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>
This commit is contained in:
Bodong Wang
2017-04-13 01:51:40 +03:00
committed by Bjorn Helgaas
parent f65fd1aa4f
commit 0e7df22401
6 changed files with 82 additions and 4 deletions
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22
Documentation/ABI/testing/sysfs-bus-pci
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@@ -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.