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Diffstat (limited to 'Documentation/PCI/pci-iov-howto.txt')
| -rw-r--r-- | Documentation/PCI/pci-iov-howto.txt | 48 |
1 files changed, 44 insertions, 4 deletions
diff --git a/Documentation/PCI/pci-iov-howto.txt b/Documentation/PCI/pci-iov-howto.txt index fc73ef5d65b8..cfaca7e69893 100644 --- a/Documentation/PCI/pci-iov-howto.txt +++ b/Documentation/PCI/pci-iov-howto.txt @@ -2,6 +2,9 @@ Copyright (C) 2009 Intel Corporation Yu Zhao <yu.zhao@intel.com> + Update: November 2012 + -- sysfs-based SRIOV enable-/disable-ment + Donald Dutile <ddutile@redhat.com> 1. Overview @@ -24,10 +27,21 @@ real existing PCI device. 2.1 How can I enable SR-IOV capability -The device driver (PF driver) will control the enabling and disabling -of the capability via API provided by SR-IOV core. If the hardware -has SR-IOV capability, loading its PF driver would enable it and all -VFs associated with the PF. +Multiple methods are available for SR-IOV enablement. +In the first method, the device driver (PF driver) will control the +enabling and disabling of the capability via API provided by SR-IOV core. +If the hardware has SR-IOV capability, loading its PF driver would +enable it and all VFs associated with the PF. Some PF drivers require +a module parameter to be set to determine the number of VFs to enable. +In the second method, a write to the sysfs file sriov_numvfs will +enable and disable the VFs associated with a PCIe PF. This method +enables per-PF, VF enable/disable values versus the first method, +which applies to all PFs of the same device. Additionally, the +PCI SRIOV core support ensures that enable/disable operations are +valid to reduce duplication in multiple drivers for the same +checks, e.g., check numvfs == 0 if enabling VFs, ensure +numvfs <= totalvfs. +The second method is the recommended method for new/future VF devices. 2.2 How can I use the Virtual Functions @@ -40,13 +54,22 @@ requires device driver that is same as a normal PCI device's. 3.1 SR-IOV API To enable SR-IOV capability: +(a) For the first method, in the driver: int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn); 'nr_virtfn' is number of VFs to be enabled. +(b) For the second method, from sysfs: + echo 'nr_virtfn' > \ + /sys/bus/pci/devices/<DOMAIN:BUS:DEVICE.FUNCTION>/sriov_numvfs To disable SR-IOV capability: +(a) For the first method, in the driver: void pci_disable_sriov(struct pci_dev *dev); +(b) For the second method, from sysfs: + echo 0 > \ + /sys/bus/pci/devices/<DOMAIN:BUS:DEVICE.FUNCTION>/sriov_numvfs To notify SR-IOV core of Virtual Function Migration: +(a) In the driver: irqreturn_t pci_sriov_migration(struct pci_dev *dev); 3.2 Usage example @@ -88,6 +111,22 @@ static void dev_shutdown(struct pci_dev *dev) ... } +static int dev_sriov_configure(struct pci_dev *dev, int numvfs) +{ + if (numvfs > 0) { + ... + pci_enable_sriov(dev, numvfs); + ... + return numvfs; + } + if (numvfs == 0) { + .... + pci_disable_sriov(dev); + ... + return 0; + } +} + static struct pci_driver dev_driver = { .name = "SR-IOV Physical Function driver", .id_table = dev_id_table, @@ -96,4 +135,5 @@ static struct pci_driver dev_driver = { .suspend = dev_suspend, .resume = dev_resume, .shutdown = dev_shutdown, + .sriov_configure = dev_sriov_configure, }; |