s390/css: Fix subchannel detection

We have to consider the m bit to find the real channel subsystem when
determining the last subchannel.

If we fail to take this into account, removal of a subchannel in
the middle of a big list of devices will stop device detection after
a reboot.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 7 insertions, 4 deletions

diff --git a/hw/s390x/css.c b/hw/s390x/css.c
index 85f6f22a7f..e526a1c86c 100644
--- a/hw/s390x/css.c
+++ b/hw/s390x/css.c
@@ -988,15 +988,18 @@ int css_do_rchp(uint8_t cssid, uint8_t chpid)
     return 0;
 }
 
-bool css_schid_final(uint8_t cssid, uint8_t ssid, uint16_t schid)
+bool css_schid_final(int m, uint8_t cssid, uint8_t ssid, uint16_t schid)
 {
     SubchSet *set;
+    uint8_t real_cssid;
 
-    if (cssid > MAX_CSSID || ssid > MAX_SSID || !channel_subsys->css[cssid] ||
-        !channel_subsys->css[cssid]->sch_set[ssid]) {
+    real_cssid = (!m && (cssid == 0)) ? channel_subsys->default_cssid : cssid;
+    if (real_cssid > MAX_CSSID || ssid > MAX_SSID ||
+        !channel_subsys->css[real_cssid] ||
+        !channel_subsys->css[real_cssid]->sch_set[ssid]) {
         return true;
     }
-    set = channel_subsys->css[cssid]->sch_set[ssid];
+    set = channel_subsys->css[real_cssid]->sch_set[ssid];
     return schid > find_last_bit(set->schids_used,
                                  (MAX_SCHID + 1) / sizeof(unsigned long));
 }