target/s390x/tcg: SPX: check validity of new prefix

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>

diff --git a/target/s390x/tcg/misc_helper.c b/target/s390x/tcg/misc_helper.c
index aab9c47747eefd9dd96ff19ce247a3f7d1653e8a..10dadb002a807bbf1408418ffb33cab210ae5026 100644 (file)
--- 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);