s390x/tcg: fix checking for invalid memory check

It should have been a >=, but let's directly perform a proper access
check to also be able to deal with hotplugged memory later.

Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20170926183318.12995-2-david@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

target/s390x/excp_helper.c

@@ -26,6 +26,7 @@
 #include "exec/exec-all.h"
 #include "exec/cpu_ldst.h"
 #include "hw/s390x/ioinst.h"
+#include "exec/address-spaces.h"
 #ifndef CONFIG_USER_ONLY
 #include "sysemu/sysemu.h"
 #endif
@@ -108,7 +109,8 @@ int s390_cpu_handle_mmu_fault(CPUState *cs, vaddr orig_vaddr,
     }
 
     /* check out of RAM access */
-    if (raddr > ram_size) {
+    if (!address_space_access_valid(&address_space_memory, raddr,
+                                    TARGET_PAGE_SIZE, rw)) {
         DPRINTF("%s: raddr %" PRIx64 " > ram_size %" PRIx64 "\n", __func__,
                 (uint64_t)raddr, (uint64_t)ram_size);
         trigger_pgm_exception(env, PGM_ADDRESSING, ILEN_AUTO);