From: Eduardo Habkost <ehabkost@redhat.com>

The disable-legacy and disable-modern properties apply only to
some virtio-pci devices.  Make those properties optional.

This fixes the crash introduced by commit f6e501a28ef9 ("virtio: Provide
version-specific variants of virtio PCI devices"):

  $ qemu-system-x86_64 -machine pc-i440fx-2.6 \
    -device virtio-net-pci-non-transitional
  Unexpected error in object_property_find() at qom/object.c:1092:
  qemu-system-x86_64: -device virtio-net-pci-non-transitional: can't apply \
  global virtio-pci.disable-modern=on: Property '.disable-modern' not found
  Aborted (core dumped)

Reported-by: Thomas Huth <thuth@redhat.com>
Fixes: f6e501a28ef9 ("virtio: Provide version-specific variants of virtio PCI devices")
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/core/machine.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/hw/core/machine.c b/hw/core/machine.c
index 95dc7c3913..f0c0ae6be8 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -91,8 +91,9 @@ const size_t hw_compat_2_7_len = G_N_ELEMENTS(hw_compat_2_7);
 
 GlobalProperty hw_compat_2_6[] = {
     { "virtio-mmio", "format_transport_address", "off" },
-    { "virtio-pci", "disable-modern", "on" },
-    { "virtio-pci", "disable-legacy", "off" },
+    /* Optional because not all virtio-pci devices support legacy mode */
+    { "virtio-pci", "disable-modern", "on",  .optional = true },
+    { "virtio-pci", "disable-legacy", "off", .optional = true },
 };
 const size_t hw_compat_2_6_len = G_N_ELEMENTS(hw_compat_2_6);
 
-- 
MST