PCI: Disable VF decoding before pcibios_sriov_disable() updates resources

A struct resource represents the address space consumed by a device.  We
should not modify that resource while the device is actively using the
address space.  For VFs, pci_iov_update_resource() enforces this by
printing a warning and doing nothing if the VFE (VF Enable) and MSE (VF
Memory Space Enable) bits are set.

Previously, both sriov_enable() and sriov_disable() called the
pcibios_sriov_disable() arch hook, which may update the struct resource,
while VFE and MSE were enabled.  This effectively dropped the resource
update pcibios_sriov_disable() intended to do.

Disable VF memory decoding before calling pcibios_sriov_disable().
Reported-by: NCarol L Soto <clsoto@us.ibm.com>
Tested-by: NCarol L Soto <clsoto@us.ibm.com>
Signed-off-by: NGavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: NAlexey Kardashevskiy <aik@ozlabs.ru>
[bhelgaas: changelog]
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Cc: shan.gavin@gmail.com
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>

drivers/pci/iov.c

@@ -331,7 +331,6 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
 	while (i--)
 		pci_iov_remove_virtfn(dev, i, 0);
 
-	pcibios_sriov_disable(dev);
 err_pcibios:
 	iov->ctrl &= ~(PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE);
 	pci_cfg_access_lock(dev);
@@ -339,6 +338,8 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
 	ssleep(1);
 	pci_cfg_access_unlock(dev);
 
+	pcibios_sriov_disable(dev);
+
 	if (iov->link != dev->devfn)
 		sysfs_remove_link(&dev->dev.kobj, "dep_link");
 
@@ -357,14 +358,14 @@ static void sriov_disable(struct pci_dev *dev)
 	for (i = 0; i < iov->num_VFs; i++)
 		pci_iov_remove_virtfn(dev, i, 0);
 
-	pcibios_sriov_disable(dev);
-
 	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);
 	ssleep(1);
 	pci_cfg_access_unlock(dev);
 
+	pcibios_sriov_disable(dev);
+
 	if (iov->link != dev->devfn)
 		sysfs_remove_link(&dev->dev.kobj, "dep_link");