PCI: Update NumVFs register when disabling SR-IOV

Currently, we only update NumVFs register during sriov_enable().
This register should also be updated during sriov_disable() and when
sriov_enable() fails.  Otherwise, we will get the stale "Number of VFs"
info from lspci.

[bhelgaas: changelog]
Signed-off-by: NYijing Wang <wangyijing@huawei.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

drivers/pci/iov.c

@@ -286,7 +286,6 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
 	    (!(iov->cap & PCI_SRIOV_CAP_VFM) && (nr_virtfn > initial)))
 		return -EINVAL;
 
-	pci_write_config_word(dev, iov->pos + PCI_SRIOV_NUM_VF, nr_virtfn);
 	pci_read_config_word(dev, iov->pos + PCI_SRIOV_VF_OFFSET, &offset);
 	pci_read_config_word(dev, iov->pos + PCI_SRIOV_VF_STRIDE, &stride);
 	if (!offset || (nr_virtfn > 1 && !stride))
@@ -334,6 +333,7 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
 			return rc;
 	}
 
+	pci_write_config_word(dev, iov->pos + PCI_SRIOV_NUM_VF, nr_virtfn);
 	iov->ctrl |= PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE;
 	pci_cfg_access_lock(dev);
 	pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
@@ -368,6 +368,7 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
 	iov->ctrl &= ~(PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE);
 	pci_cfg_access_lock(dev);
 	pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
+	pci_write_config_word(dev, iov->pos + PCI_SRIOV_NUM_VF, 0);
 	ssleep(1);
 	pci_cfg_access_unlock(dev);
 
@@ -401,6 +402,7 @@ static void sriov_disable(struct pci_dev *dev)
 		sysfs_remove_link(&dev->dev.kobj, "dep_link");
 
 	iov->num_VFs = 0;
+	pci_write_config_word(dev, iov->pos + PCI_SRIOV_NUM_VF, 0);
 }
 
 static int sriov_init(struct pci_dev *dev, int pos)