PCI: Do any VF BAR updates before enabling the BARs

Previously we enabled VFs and enable their memory space before calling
pcibios_sriov_enable().  But pcibios_sriov_enable() may update the VF BARs:
for example, on PPC PowerNV we may change them to manage the association of
VFs to PEs.

Because 64-bit BARs cannot be updated atomically, it's unsafe to update
them while they're enabled.  The half-updated state may conflict with other
devices in the system.

Call pcibios_sriov_enable() before enabling the VFs so any BAR updates
happen while the VF BARs are disabled.

[bhelgaas: changelog]
Tested-by: Carol Soto <clsoto@us.ibm.com>
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index e30f05c..d41ec29 100644 (file)
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -306,13 +306,6 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
                        return rc;
        }
 
-       pci_iov_set_numvfs(dev, 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);
-       msleep(100);
-       pci_cfg_access_unlock(dev);
-
        iov->initial_VFs = initial;
        if (nr_virtfn < initial)
                initial = nr_virtfn;
@@ -323,6 +316,13 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
                goto err_pcibios;
        }
 
+       pci_iov_set_numvfs(dev, 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);
+       msleep(100);
+       pci_cfg_access_unlock(dev);
+
        for (i = 0; i < initial; i++) {
                rc = pci_iov_add_virtfn(dev, i, 0);
                if (rc)