From: Janis Schoetterl-Glausch <scgl@linux.ibm.com>

According to the architecture, SET PREFIX must try to access the new
prefix area and recognize an addressing exception if the area is not
accessible.
For qemu this check prevents a crash in cpu_map_lowcore after an
inaccessible prefix area has been set.

Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Message-Id: <20220630094340.3646279-1-scgl@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 target/s390x/tcg/misc_helper.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/target/s390x/tcg/misc_helper.c b/target/s390x/tcg/misc_helper.c
index aab9c47747..10dadb002a 100644
--- a/target/s390x/tcg/misc_helper.c
+++ b/target/s390x/tcg/misc_helper.c
@@ -158,6 +158,13 @@ void HELPER(spx)(CPUS390XState *env, uint64_t a1)
     if (prefix == old_prefix) {
         return;
     }
+    /*
+     * Since prefix got aligned to 8k and memory increments are a multiple of
+     * 8k checking the first page is sufficient
+     */
+    if (!mmu_absolute_addr_valid(prefix, true)) {
+        tcg_s390_program_interrupt(env, PGM_ADDRESSING, GETPC());
+    }
 
     env->psa = prefix;
     HELPER_LOG("prefix: %#x\n", prefix);
-- 
2.31.1