pci: Add SRIOV helper function to determine if VFs are assigned to guest

This function is meant to add a helper function that will determine if a PF
has any VFs that are currently assigned to a guest.  We currently have been
implementing this function per driver, and going forward I would like to avoid
that by making this function generic and using this helper.

v2: Removed extern from declaration of pci_vfs_assigned in pci.h and return
    0 if SR-IOV is disabled with is inline with other PCI SRIOV functions.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

1 files changed, 41 insertions, 0 deletions

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index ee599f274f05..c93071d428f5 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -729,6 +729,47 @@ int pci_num_vf(struct pci_dev *dev)
 EXPORT_SYMBOL_GPL(pci_num_vf);
 
 /**
+ * pci_vfs_assigned - returns number of VFs are assigned to a guest
+ * @dev: the PCI device
+ *
+ * Returns number of VFs belonging to this device that are assigned to a guest.
+ * If device is not a physical function returns -ENODEV.
+ */
+int pci_vfs_assigned(struct pci_dev *dev)
+{
+        struct pci_dev *vfdev;
+        unsigned int vfs_assigned = 0;
+        unsigned short dev_id;
+
+        /* only search if we are a PF */
+        if (!dev->is_physfn)
+                return 0;
+
+        /*
+         * determine the device ID for the VFs, the vendor ID will be the
+         * same as the PF so there is no need to check for that one
+         */
+        pci_read_config_word(dev, dev->sriov->pos + PCI_SRIOV_VF_DID, &dev_id);
+
+        /* loop through all the VFs to see if we own any that are assigned */
+        vfdev = pci_get_device(dev->vendor, dev_id, NULL);
+        while (vfdev) {
+                /*
+                 * It is considered assigned if it is a virtual function with
+                 * our dev as the physical function and the assigned bit is set
+                 */
+                if (vfdev->is_virtfn && (vfdev->physfn == dev) &&
+                    (vfdev->dev_flags & PCI_DEV_FLAGS_ASSIGNED))
+                        vfs_assigned++;
+
+                vfdev = pci_get_device(dev->vendor, dev_id, vfdev);
+        }
+
+        return vfs_assigned;
+}
+EXPORT_SYMBOL_GPL(pci_vfs_assigned);
+
+/**
  * pci_sriov_set_totalvfs -- reduce the TotalVFs available
  * @dev: the PCI PF device
  * @numvfs: number that should be used for TotalVFs supported