[PATCH 2/2] PCI: Calculate the VF bus range on each possible NumVFs

[Wei Yang <weiyang@linux.vnet.ibm.com>]

Per SRIOV SPEC section 3.3.10 and 3.3.11, VF Stride and VF Offset may change
when NumVFs changes. This will affect the bus range for VFs.

This patch iterates on each possible NumVFs and calculate the maximum bus
range for VFs.

Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com>
---
 drivers/pci/iov.c |   31 +++++++++++++++++++++++++++----
 drivers/pci/pci.h |    1 +
 2 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index ef0ceaa..ea3a82c 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -46,6 +46,30 @@ static inline void pci_iov_set_numvfs(struct pci_dev *dev, int nr_virtfn)
 	pci_read_config_word(dev, iov->pos + PCI_SRIOV_VF_STRIDE, &iov->stride);
 }
 
+/**
+ * Per SRIOV SPEC section 3.3.10 and 3.3.11, VF Stride and VF offset may
+ * change when NumVFs changes. Which will affect the bus range for VFs.
+ *
+ * This function iterate on all valide NumVFs and calculate the maximum bus
+ * range for VFs.
+ */
+static inline void pci_iov_max_bus_range(struct pci_dev *dev)
+{
+	struct pci_sriov *iov = dev->sriov;
+	int total = iov->total_VFs;
+	u8 max = 0;
+	u8 busnr;
+
+	for ( ; total >= 0; total--) {
+		pci_iov_set_numvfs(dev, total);
+		busnr = virtfn_bus(dev, iov->total_VFs - 1);
+		if (busnr > max)
+			max = busnr;
+	}
+
+	iov->max_bus_range = max;
+}
+
 static struct pci_bus *virtfn_add_bus(struct pci_bus *bus, int busnr)
 {
 	struct pci_bus *child;
@@ -415,6 +439,7 @@ found:
 
 	dev->sriov = iov;
 	dev->is_physfn = 1;
+	pci_iov_max_bus_range(dev);
 
 	return 0;
 
@@ -550,15 +575,13 @@ void pci_restore_iov_state(struct pci_dev *dev)
 int pci_iov_bus_range(struct pci_bus *bus)
 {
 	int max = 0;
-	u8 busnr;
 	struct pci_dev *dev;
 
 	list_for_each_entry(dev, &bus->devices, bus_list) {
 		if (!dev->is_physfn)
 			continue;
-		busnr = virtfn_bus(dev, dev->sriov->total_VFs - 1);
-		if (busnr > max)
-			max = busnr;
+		if (dev->sriov->max_bus_range > max)
+			max = dev->sriov->max_bus_range;
 	}
 
 	return max ? max - bus->number : 0;
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 8aff29a..94faf97 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -236,6 +236,7 @@ struct pci_sriov {
 	u16 stride;		/* following VF stride */
 	u32 pgsz;		/* page size for BAR alignment */
 	u8 link;		/* Function Dependency Link */
+	u8 max_bus_range;	/* Maximum bus range a VF could sit*/
 	u16 driver_max_VFs;	/* max num VFs driver supports */
 	struct pci_dev *dev;	/* lowest numbered PF */
 	struct pci_dev *self;	/* this PF */
-- 
1.7.9.5