[pci PATCH v8 1/4] pci: Add pci_sriov_configure_simple for PFs that don't manage VF resources

[Alexander Duyck <alexander.h.duyck@xxxxxxxxx>]

This patch adds a common configuration function called
pci_sriov_configure_simple that will allow for managing VFs on devices
where the PF is not capable of managing VF resources.

Signed-off-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxx>
Tested-by: Mark Rustad <mark.d.rustad@xxxxxxxxx>
---

v5: New patch replacing pci_sriov_configure_unmanaged with
      pci_sriov_configure_simple
    Dropped bits related to autoprobe changes
v6: Defined pci_sriov_configure_simple as NULL if IOV is disabled
v7: Updated pci_sriov_configure_simple to drop need for err value
    Fixed comment explaining why pci_sriov_configure_simple is NULL

 drivers/pci/iov.c   |   31 +++++++++++++++++++++++++++++++
 include/linux/pci.h |    3 +++
 2 files changed, 34 insertions(+)

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 677924a..3e0a7fd 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -807,3 +807,34 @@ int pci_sriov_get_totalvfs(struct pci_dev *dev)
 	return dev->sriov->total_VFs;
 }
 EXPORT_SYMBOL_GPL(pci_sriov_get_totalvfs);
+
+/**
+ * pci_sriov_configure_simple - helper to configure unmanaged SR-IOV
+ * @dev: the PCI device
+ * @nr_virtfn: number of virtual functions to enable, 0 to disable
+ *
+ * Used to provide generic enable/disable SR-IOV option for devices
+ * that do not manage the VFs generated by their driver. Return value
+ * is negative on error, or number of VFs allocated on success.
+ */
+int pci_sriov_configure_simple(struct pci_dev *dev, int nr_virtfn)
+{
+	might_sleep();
+
+	if (!dev->is_physfn)
+		return -ENODEV;
+
+	if (pci_vfs_assigned(dev)) {
+		pci_warn(dev,
+			 "Cannot modify SR-IOV while VFs are assigned\n");
+		return -EPERM;
+	}
+
+	if (!nr_virtfn) {
+		sriov_disable(dev);
+		return 0;
+	}
+
+	return sriov_enable(dev, nr_virtfn) ? : nr_virtfn;
+}
+EXPORT_SYMBOL_GPL(pci_sriov_configure_simple);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index ae42289..7d36e39 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1955,6 +1955,7 @@ static inline void pci_mmcfg_late_init(void) { }
 int pci_vfs_assigned(struct pci_dev *dev);
 int pci_sriov_set_totalvfs(struct pci_dev *dev, u16 numvfs);
 int pci_sriov_get_totalvfs(struct pci_dev *dev);
+int pci_sriov_configure_simple(struct pci_dev *dev, int nr_virtfn);
 resource_size_t pci_iov_resource_size(struct pci_dev *dev, int resno);
 void pci_vf_drivers_autoprobe(struct pci_dev *dev, bool probe);
 #else
@@ -1982,6 +1983,8 @@ static inline int pci_sriov_set_totalvfs(struct pci_dev *dev, u16 numvfs)
 { return 0; }
 static inline int pci_sriov_get_totalvfs(struct pci_dev *dev)
 { return 0; }
+/* this is expected to be used as a function pointer, just define as NULL */
+#define pci_sriov_configure_simple NULL
 static inline resource_size_t pci_iov_resource_size(struct pci_dev *dev, int resno)
 { return 0; }
 static inline void pci_vf_drivers_autoprobe(struct pci_dev *dev, bool probe) { }