xen/pciback: Check PF instead of VF for PCI_COMMAND_MEMORY

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 <konrad.wilk@oracle.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/xen/xen-pciback/pciback_ops.c b/drivers/xen/xen-pciback/pciback_ops.c
index 31c8580..6e1b06b 100644 (file)
--- a/drivers/xen/xen-pciback/pciback_ops.c
+++ b/drivers/xen/xen-pciback/pciback_ops.c
@@ -225,8 +225,9 @@ 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;