tests/postcopy: Use KVM on ppc64 only if it is KVM-HV

The ppc64 postcopy test does not work with KVM-PR, and it is also
causing annoying warning messages when run on a x86 host. So let's
use KVM here only if we know that we're running with KVM-HV (which
automatically also means that we're running on a ppc64 host), and
fall back to TCG otherwise.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

tests/postcopy-test.c

@@ -380,17 +380,21 @@ static void test_migrate(void)
                                   " -incoming %s",
                                   tmpfs, bootpath, uri);
     } else if (strcmp(arch, "ppc64") == 0) {
+        const char *accel;
+
+        /* On ppc64, the test only works with kvm-hv, but not with kvm-pr */
+        accel = access("/sys/module/kvm_hv", F_OK) ? "tcg" : "kvm:tcg";
         init_bootfile_ppc(bootpath);
-        cmd_src = g_strdup_printf("-machine accel=kvm:tcg -m 256M"
+        cmd_src = g_strdup_printf("-machine accel=%s -m 256M"
                                   " -name pcsource,debug-threads=on"
                                   " -serial file:%s/src_serial"
                                   " -drive file=%s,if=pflash,format=raw",
-                                  tmpfs, bootpath);
-        cmd_dst = g_strdup_printf("-machine accel=kvm:tcg -m 256M"
+                                  accel, tmpfs, bootpath);
+        cmd_dst = g_strdup_printf("-machine accel=%s -m 256M"
                                   " -name pcdest,debug-threads=on"
                                   " -serial file:%s/dest_serial"
                                   " -incoming %s",
-                                  tmpfs, uri);
+                                  accel, tmpfs, uri);
     } else {
         g_assert_not_reached();
     }