s390x/css: handle emw correctly for tsch

We should not try to store the emw portion of the irb if extended
measurements are not applicable. In particular, we should not surprise
the guest by storing a larger irb if it did not enable extended
measurements.

Cc: qemu-stable@nongnu.org
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
(cherry picked from commit f068d320def7fd83bf0fcdca37b305f1c2ac5413)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

diff --git a/hw/s390x/css.c b/hw/s390x/css.c
index 7074d2b3d5b49f067ec1c4555da3f7da2e7cad29..d68a29a82aa1e31f46f9f0b8bb397e31b499366e 100644 (file)
--- a/hw/s390x/css.c
+++ b/hw/s390x/css.c
@@ -734,9 +734,11 @@ out:
     return ret;
 }
 
-static void copy_irb_to_guest(IRB *dest, const IRB *src)
+static void copy_irb_to_guest(IRB *dest, const IRB *src, PMCW *pmcw)
 {
     int i;
+    uint16_t stctl = src->scsw.ctrl & SCSW_CTRL_MASK_STCTL;
+    uint16_t actl = src->scsw.ctrl & SCSW_CTRL_MASK_ACTL;
 
     copy_scsw_to_guest(&dest->scsw, &src->scsw);
 
@@ -746,8 +748,22 @@ static void copy_irb_to_guest(IRB *dest, const IRB *src)
     for (i = 0; i < ARRAY_SIZE(dest->ecw); i++) {
         dest->ecw[i] = cpu_to_be32(src->ecw[i]);
     }
-    for (i = 0; i < ARRAY_SIZE(dest->emw); i++) {
-        dest->emw[i] = cpu_to_be32(src->emw[i]);
+    /* extended measurements enabled? */
+    if ((src->scsw.flags & SCSW_FLAGS_MASK_ESWF) ||
+        !(pmcw->flags & PMCW_FLAGS_MASK_TF) ||
+        !(pmcw->chars & PMCW_CHARS_MASK_XMWME)) {
+        return;
+    }
+    /* extended measurements pending? */
+    if (!(stctl & SCSW_STCTL_STATUS_PEND)) {
+        return;
+    }
+    if ((stctl & SCSW_STCTL_PRIMARY) ||
+        (stctl == SCSW_STCTL_SECONDARY) ||
+        ((stctl & SCSW_STCTL_INTERMEDIATE) && (actl & SCSW_ACTL_SUSP))) {
+        for (i = 0; i < ARRAY_SIZE(dest->emw); i++) {
+            dest->emw[i] = cpu_to_be32(src->emw[i]);
+        }
     }
 }
 
@@ -793,7 +809,7 @@ int css_do_tsch(SubchDev *sch, IRB *target_irb)
         }
     }
     /* Store the irb to the guest. */
-    copy_irb_to_guest(target_irb, &irb);
+    copy_irb_to_guest(target_irb, &irb, p);
 
     /* Clear conditions on subchannel, if applicable. */
     if (stctl & SCSW_STCTL_STATUS_PEND) {