From 0e7df22401a3dfd403b26dea62dd00e0598b538b Mon Sep 17 00:00:00 2001 From: Bodong Wang Date: Thu, 13 Apr 2017 01:51:40 +0300 Subject: 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//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 Signed-off-by: Eli Cohen Signed-off-by: Bjorn Helgaas Reviewed-by: Gavin Shan Reviewed-by: Alex Williamson --- Documentation/ABI/testing/sysfs-bus-pci | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'Documentation/ABI/testing/sysfs-bus-pci') 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 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 +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. -- cgit v1.2.3