[kvm-unit-tests PATCH] s390x: Add a test for the diagnose 0x308 hypercall

[Thomas Huth <thuth@redhat.com>]

The original idea for this test is to have an easy way to check for a
problem that has been fixed in QEMU recently: QEMU simply aborted if this
diagnose call was called with an unsupported subcode (e.g. 2). The problem
has been fixed in QEMU commit 37dbd1f4d4805edcd18d94eb202bb3461b3cd52d
("Return specification exception for unimplemented diag 308 subcodes"),
and this test now should make sure that we do not regress here again.
While we're at it, also check whether LOAD NORMAL via subcode 1 works
correctly, whether the diagnose call is blocked correctly in problem state
and whether subcodes 5 and 6 are generating specification exceptions for
illegal parameters as expected.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 s390x/Makefile      |   1 +
 s390x/diag308.c     | 130 ++++++++++++++++++++++++++++++++++++++++++++
 s390x/unittests.cfg |   3 +
 3 files changed, 134 insertions(+)
 create mode 100644 s390x/diag308.c

diff --git a/s390x/Makefile b/s390x/Makefile
index af40fd4..1f21ddb 100644
--- a/s390x/Makefile
+++ b/s390x/Makefile
@@ -5,6 +5,7 @@ tests += $(TEST_DIR)/sieve.elf
 tests += $(TEST_DIR)/sthyi.elf
 tests += $(TEST_DIR)/skey.elf
 tests += $(TEST_DIR)/diag10.elf
+tests += $(TEST_DIR)/diag308.elf
 tests += $(TEST_DIR)/pfmf.elf
 tests += $(TEST_DIR)/cmm.elf
 tests += $(TEST_DIR)/vector.elf
diff --git a/s390x/diag308.c b/s390x/diag308.c
new file mode 100644
index 0000000..4d5fd48
--- /dev/null
+++ b/s390x/diag308.c
@@ -0,0 +1,130 @@
+/*
+ * Diagnose 0x308 hypercall tests
+ *
+ * Copyright (c) 2019 Thomas Huth, Red Hat Inc.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2, or (at
+ * your option) any later version.
+ */
+
+#include <libcflat.h>
+#include <asm/asm-offsets.h>
+#include <asm/interrupt.h>
+
+/* The diagnose calls should be blocked in problem state */
+static void test_priv(void)
+{
+	expect_pgm_int();
+	enter_pstate();
+	asm volatile ("diag %0,%1,0x308" :: "a"(0), "a"(3));
+	check_pgm_int_code(PGM_INT_CODE_PRIVILEGED_OPERATION);
+}
+
+/*
+ * Check that diag308 with subcode 1 loads the PSW at address 0, i.e.
+ * that we can put a pointer into address 4 which then gets executed.
+ */
+static void test_subcode1(void)
+{
+	uint64_t saved_psw = *(uint64_t *)0;
+	long subcode = 1;
+	long ret;
+
+	asm volatile (
+		"	llilh	%0,0x0008\n"
+		"	st	%0,0\n"
+		"	larl	%0,0f\n"
+		"	oilh	%0,0x8000\n"
+		"	st	%0,4\n"
+		"	diag	0,%1,0x308\n"
+		"	lghi	%0,0\n"
+		"	j	1f\n"
+		"0:	lghi	%0,1\n"
+		"1:"
+		: "=&a"(ret) : "a"(subcode) : "memory");
+
+	*(uint64_t *)0 = saved_psw;
+
+	report("load normal reset done", ret == 1);
+}
+
+/* Expect a specification exception when using an uneven register */
+static void test_uneven_reg(unsigned int subcode)
+{
+	register unsigned long sc asm("6") = subcode;
+	register unsigned long r3 asm("9") = 0x2000;
+
+	report_prefix_push("uneven register");
+	expect_pgm_int();
+	asm volatile ("diag %0,%1,0x308" :: "a"(r3), "a"(sc));
+	check_pgm_int_code(PGM_INT_CODE_SPECIFICATION);
+	report_prefix_pop();
+}
+
+/* Expect a specification exception when using an unaligned address */
+static void test_unaligned_address(unsigned int subcode)
+{
+	register unsigned long sc asm("6") = subcode;
+	register unsigned long addr asm("8") = 54321;
+
+	report_prefix_push("unaligned address");
+	expect_pgm_int();
+	asm volatile ("diag %0,%1,0x308" :: "a"(addr), "a"(sc));
+	check_pgm_int_code(PGM_INT_CODE_SPECIFICATION);
+	report_prefix_pop();
+}
+
+static void test_subcode5(void)
+{
+	test_uneven_reg(5);
+	test_unaligned_address(5);
+}
+
+static void test_subcode6(void)
+{
+	test_uneven_reg(6);
+	test_unaligned_address(6);
+}
+
+/* Unsupported subcodes should generate a specification exception */
+static void test_unsupported_subcode(void)
+{
+	int subcodes[] = { 2, 0x101, 0xffff, 0x10001, -1 };
+	int idx;
+
+	for (idx = 0; idx < ARRAY_SIZE(subcodes); idx++) {
+		report_prefix_pushf("0x%04x", subcodes[idx]);
+		expect_pgm_int();
+		asm volatile ("diag %0,%1,0x308" :: "a"(0), "a"(subcodes[idx]));
+		check_pgm_int_code(PGM_INT_CODE_SPECIFICATION);
+		report_prefix_pop();
+	}
+}
+
+static struct {
+	const char *name;
+	void (*func)(void);
+} tests[] = {
+	{ "privileged", test_priv },
+	{ "subcode 1", test_subcode1 },
+	{ "subcode 5", test_subcode5 },
+	{ "subcode 6", test_subcode6 },
+	{ "unsupported", test_unsupported_subcode },
+	{ NULL, NULL }
+};
+
+int main(int argc, char**argv)
+{
+	int i;
+
+	report_prefix_push("diag308");
+	for (i = 0; tests[i].name; i++) {
+		report_prefix_push(tests[i].name);
+		tests[i].func();
+		report_prefix_pop();
+	}
+	report_prefix_pop();
+
+	return report_summary();
+}
diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg
index e53c365..546b1f2 100644
--- a/s390x/unittests.cfg
+++ b/s390x/unittests.cfg
@@ -44,6 +44,9 @@ file = skey.elf
 [diag10]
 file = diag10.elf
 
+[diag308]
+file = diag308.elf
+
 [pfmf]
 file = pfmf.elf
 
-- 
2.21.0