[PATCH v2] hw/pci: add comment explaining the reason for checking function 0 in hotplug

[PATCH v2] hw/pci: add comment explaining the reason for checking function 0 in hotplug

[Ani Sinha]

This change is cosmetic. A comment is added explaining why we need to check for
the availability of function 0 when we hotplug a device.

CC: mst@redhat.com
Signed-off-by: Ani Sinha <anisinha@redhat.com>
---
 hw/pci/pci.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

changelog:
v2: moved comment location as per mst suggestion.

diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index bf38905b7d..459c7123a8 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -1179,7 +1179,13 @@ static PCIDevice *do_pci_register_device(PCIDevice *pci_dev,
                    PCI_SLOT(devfn), PCI_FUNC(devfn), name,
                    bus->devices[devfn]->name, bus->devices[devfn]->qdev.id);
         return NULL;
-    } else if (dev->hotplugged &&
+    }
+    /*
+     * Populating function 0 triggers a scan from the guest that
+     * exposes other non-zero functions. Hence we need to ensure that
+     * function 0 wasn't added yet.
+     */
+    else if (dev->hotplugged &&
                !pci_is_vf(pci_dev) &&
                pci_get_function_0(pci_dev)) {
         error_setg(errp, "PCI: slot %d function 0 already occupied by %s,"
-- 
2.39.1