s390x/css: realize css_create_sch

The S390 virtual css support already has a mechanism to create a
virtual subchannel and provide it to the guest. However, to
pass-through subchannels to a guest, we need to introduce a new
mechanism to create the subchannel according to the real device
information. Thus we reconstruct css_create_virtual_sch to a new
css_create_sch function to handle all these cases and do allocation
and initialization of the subchannel according to the device type
and machine configuration.

Reviewed-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Message-Id: <20170517004813.58227-6-bjsdjshi@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

1 files changed, 8 insertions, 3 deletions

diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
index cd007ca8cf..c9021f2fa9 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -136,10 +136,15 @@ static void ccw_init(MachineState *machine)
         kvm_s390_enable_css_support(s390_cpu_addr2state(0));
     }
     /*
-     * Create virtual css and set it as default so that non mcss-e
-     * enabled guests only see virtio devices.
+     * Non mcss-e enabled guests only see the devices from the default
+     * css, which is determined by the value of the squash_mcss property.
+     * Note: we must not squash non virtual devices to css 0xFE.
      */
-    ret = css_create_css_image(VIRTUAL_CSSID, true);
+    if (css_bus->squash_mcss) {
+        ret = css_create_css_image(0, true);
+    } else {
+        ret = css_create_css_image(VIRTUAL_CSSID, true);
+    }
     assert(ret == 0);
 
     /* Create VirtIO network adapters */