4.2.8-ckt5 -stable review patch.  If anyone has any objections, please let me 
know.

---8<------------------------------------------------------------

From: Konrad Rzeszutek Wilk <[email protected]>

commit 8d47065f7d1980dde52abb874b301054f3013602 upstream.

Commit 408fb0e5aa7fda0059db282ff58c3b2a4278baa0 (xen/pciback: Don't
allow MSI-X ops if PCI_COMMAND_MEMORY is not set) prevented enabling
MSI-X on passed-through virtual functions, because it checked the VF
for PCI_COMMAND_MEMORY but this is not a valid bit for VFs.

Instead, check the physical function for PCI_COMMAND_MEMORY.

Signed-off-by: Konrad Rzeszutek Wilk <[email protected]>
Reviewed-by: Jan Beulich <[email protected]>
Signed-off-by: David Vrabel <[email protected]>
Signed-off-by: Kamal Mostafa <[email protected]>
---
 drivers/xen/xen-pciback/pciback_ops.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/xen-pciback/pciback_ops.c 
b/drivers/xen/xen-pciback/pciback_ops.c
index 73dafdc..1078e8d 100644
--- a/drivers/xen/xen-pciback/pciback_ops.c
+++ b/drivers/xen/xen-pciback/pciback_ops.c
@@ -227,8 +227,9 @@ int xen_pcibk_enable_msix(struct xen_pcibk_device *pdev,
        /*
         * PCI_COMMAND_MEMORY must be enabled, otherwise we may not be able
         * to access the BARs where the MSI-X entries reside.
+        * But VF devices are unique in which the PF needs to be checked.
         */
-       pci_read_config_word(dev, PCI_COMMAND, &cmd);
+       pci_read_config_word(pci_physfn(dev), PCI_COMMAND, &cmd);
        if (dev->msi_enabled || !(cmd & PCI_COMMAND_MEMORY))
                return -ENXIO;
 
-- 
2.7.0

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