1 files changed, 22 insertions, 19 deletions

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 0cdb2d1e1a20..1b1acc27141c 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -54,24 +54,29 @@ static inline void pci_iov_set_numvfs(struct pci_dev *dev, int nr_virtfn)
  * The PF consumes one bus number.  NumVFs, First VF Offset, and VF Stride
  * determine how many additional bus numbers will be consumed by VFs.
  *
- * Iterate over all valid NumVFs and calculate the maximum number of bus
- * numbers that could ever be required.
+ * Iterate over all valid NumVFs, validate offset and stride, and calculate
+ * the maximum number of bus numbers that could ever be required.
  */
-static inline u8 virtfn_max_buses(struct pci_dev *dev)
+static int compute_max_vf_buses(struct pci_dev *dev)
 {
 	struct pci_sriov *iov = dev->sriov;
-	int nr_virtfn;
-	u8 max = 0;
-	int busnr;
+	int nr_virtfn, busnr, rc = 0;
 
-	for (nr_virtfn = 1; nr_virtfn <= iov->total_VFs; nr_virtfn++) {
+	for (nr_virtfn = iov->total_VFs; nr_virtfn; nr_virtfn--) {
 		pci_iov_set_numvfs(dev, nr_virtfn);
+		if (!iov->offset || (nr_virtfn > 1 && !iov->stride)) {
+			rc = -EIO;
+			goto out;
+		}
+
 		busnr = pci_iov_virtfn_bus(dev, nr_virtfn - 1);
-		if (busnr > max)
-			max = busnr;
+		if (busnr > iov->max_VF_buses)
+			iov->max_VF_buses = busnr;
 	}
 
-	return max;
+out:
+	pci_iov_set_numvfs(dev, 0);
+	return rc;
 }
 
 static struct pci_bus *virtfn_add_bus(struct pci_bus *bus, int busnr)
@@ -384,7 +389,7 @@ static int sriov_init(struct pci_dev *dev, int pos)
 	int rc;
 	int nres;
 	u32 pgsz;
-	u16 ctrl, total, offset, stride;
+	u16 ctrl, total;
 	struct pci_sriov *iov;
 	struct resource *res;
 	struct pci_dev *pdev;
@@ -410,11 +415,6 @@ static int sriov_init(struct pci_dev *dev, int pos)
 
 found:
 	pci_write_config_word(dev, pos + PCI_SRIOV_CTRL, ctrl);
-	pci_write_config_word(dev, pos + PCI_SRIOV_NUM_VF, 0);
-	pci_read_config_word(dev, pos + PCI_SRIOV_VF_OFFSET, &offset);
-	pci_read_config_word(dev, pos + PCI_SRIOV_VF_STRIDE, &stride);
-	if (!offset || (total > 1 && !stride))
-		return -EIO;
 
 	pci_read_config_word(dev, pos + PCI_SRIOV_TOTAL_VF, &total);
 	if (!total)
@@ -456,8 +456,6 @@ found:
 	iov->nres = nres;
 	iov->ctrl = ctrl;
 	iov->total_VFs = total;
-	iov->offset = offset;
-	iov->stride = stride;
 	iov->pgsz = pgsz;
 	iov->self = dev;
 	pci_read_config_dword(dev, pos + PCI_SRIOV_CAP, &iov->cap);
@@ -474,10 +472,15 @@ found:
 
 	dev->sriov = iov;
 	dev->is_physfn = 1;
-	iov->max_VF_buses = virtfn_max_buses(dev);
+	rc = compute_max_vf_buses(dev);
+	if (rc)
+		goto fail_max_buses;
 
 	return 0;
 
+fail_max_buses:
+	dev->sriov = NULL;
+	dev->is_physfn = 0;
 failed:
 	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
 		res = &dev->resource[i + PCI_IOV_RESOURCES];