s390x/cpumodel: we are always in zarchitecture mode

In QEMU, a guest VCPU always started in and never was able to leave
z/Architecture mode. Now we have an architected way of showing this
condition.

The SIGP SET ARCHITECTURE instruction is simply rejected. Linux as guest
seems to not care about the return value, which is a good thing
The new handling is just like already being in z/Architecture mode.

We'll not try to fake absence of this facility, but still not indicate
the facility in case some strange CPU model turned z/Architecture off
completely (which doesn't work either way but let's us see how a
guest would react on a lack of this facility).

Signed-off-by: Jason J. Herne <jjherne@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

2 files changed, 14 insertions, 29 deletions

diff --git a/target/s390x/cpu_features.c b/target/s390x/cpu_features.c
index e5a3f71492..fa887d9b6f 100644
--- a/target/s390x/cpu_features.c
+++ b/target/s390x/cpu_features.c
@@ -337,8 +337,9 @@ void s390_fill_feat_block(const S390FeatBitmap features, S390FeatType type,
     int bit_nr;
 
     if (type == S390_FEAT_TYPE_STFL && test_bit(S390_FEAT_ZARCH, features)) {
-        /* z/Architecture is always active if around */
-        data[0] |= 0x20;
+        /* Features that are always active */
+        data[0] |= 0x20;  /* z/Architecture */
+        data[17] |= 0x20; /* Configuration-z-architectural-mode */
     }
 
     feat = find_first_bit(features, S390_FEAT_MAX);
diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
index 3a80f1fc49..8c6cc0aaf7 100644
--- a/target/s390x/kvm.c
+++ b/target/s390x/kvm.c
@@ -1757,41 +1757,25 @@ static int sigp_set_architecture(S390CPU *cpu, uint32_t param,
 {
     CPUState *cur_cs;
     S390CPU *cur_cpu;
+    bool all_stopped = true;
 
-    /* due to the BQL, we are the only active cpu */
     CPU_FOREACH(cur_cs) {
         cur_cpu = S390_CPU(cur_cs);
-        if (cur_cpu->env.sigp_order != 0) {
-            return SIGP_CC_BUSY;
+
+        if (cur_cpu == cpu) {
+            continue;
         }
-        cpu_synchronize_state(cur_cs);
-        /* all but the current one have to be stopped */
-        if (cur_cpu != cpu &&
-            s390_cpu_get_state(cur_cpu) != CPU_STATE_STOPPED) {
-            *status_reg &= 0xffffffff00000000ULL;
-            *status_reg |= SIGP_STAT_INCORRECT_STATE;
-            return SIGP_CC_STATUS_STORED;
+        if (s390_cpu_get_state(cur_cpu) != CPU_STATE_STOPPED) {
+            all_stopped = false;
         }
     }
 
-    switch (param & 0xff) {
-    case SIGP_MODE_ESA_S390:
-        /* not supported */
-        return SIGP_CC_NOT_OPERATIONAL;
-    case SIGP_MODE_Z_ARCH_TRANS_ALL_PSW:
-    case SIGP_MODE_Z_ARCH_TRANS_CUR_PSW:
-        CPU_FOREACH(cur_cs) {
-            cur_cpu = S390_CPU(cur_cs);
-            cur_cpu->env.pfault_token = -1UL;
-        }
-        break;
-    default:
-        *status_reg &= 0xffffffff00000000ULL;
-        *status_reg |= SIGP_STAT_INVALID_PARAMETER;
-        return SIGP_CC_STATUS_STORED;
-    }
+    *status_reg &= 0xffffffff00000000ULL;
 
-    return SIGP_CC_ORDER_CODE_ACCEPTED;
+    /* Reject set arch order, with czam we're always in z/Arch mode. */
+    *status_reg |= (all_stopped ? SIGP_STAT_INVALID_PARAMETER :
+                    SIGP_STAT_INCORRECT_STATE);
+    return SIGP_CC_STATUS_STORED;
 }
 
 static int handle_sigp(S390CPU *cpu, struct kvm_run *run, uint8_t ipa1)