[kvm-unit-tests PATCH v1 3/3] s390x: add pgm spec interrupt loop test

[Nico Boehr <nrb@linux.ibm.com>]

An invalid PSW causes a program interrupt. When an invalid PSW is
introduced in the pgm_new_psw, an interrupt loop occurs as soon as a
program interrupt is caused.

QEMU should detect that and panick the guest, hence add a test for it.

Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
---
 s390x/Makefile      |  1 +
 s390x/pgmint-loop.c | 46 +++++++++++++++++++++++++++++++++++++++++++++
 s390x/unittests.cfg |  4 ++++
 3 files changed, 51 insertions(+)
 create mode 100644 s390x/pgmint-loop.c

diff --git a/s390x/Makefile b/s390x/Makefile
index 92a020234c9f..a600dbfb3f4c 100644
--- a/s390x/Makefile
+++ b/s390x/Makefile
@@ -35,6 +35,7 @@ tests += $(TEST_DIR)/pv-attest.elf
 tests += $(TEST_DIR)/migration-cmm.elf
 tests += $(TEST_DIR)/migration-skey.elf
 tests += $(TEST_DIR)/extint-loop.elf
+tests += $(TEST_DIR)/pgmint-loop.elf
 
 pv-tests += $(TEST_DIR)/pv-diags.elf
 
diff --git a/s390x/pgmint-loop.c b/s390x/pgmint-loop.c
new file mode 100644
index 000000000000..5b74f26dbc3d
--- /dev/null
+++ b/s390x/pgmint-loop.c
@@ -0,0 +1,46 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Program interrupt loop test
+ *
+ * Copyright IBM Corp. 2022
+ *
+ * Authors:
+ *  Nico Boehr <nrb@linux.ibm.com>
+ */
+#include <libcflat.h>
+#include <bitops.h>
+#include <asm/interrupt.h>
+#include <asm/barrier.h>
+
+static void pgm_int_handler(void)
+{
+	/*
+	 * return to pgm_old_psw. This gives us the chance to print the return_fail
+	 * in case something goes wrong.
+	 */
+	asm volatile (
+		"lpswe %[pgm_old_psw]\n"
+		:
+		: [pgm_old_psw] "Q"(lowcore.pgm_old_psw)
+		: "memory"
+	);
+}
+
+int main(void)
+{
+	report_prefix_push("pgmint-loop");
+
+	lowcore.pgm_new_psw.addr = (uint64_t) pgm_int_handler;
+	/* bit 12 set is invalid */
+	lowcore.pgm_new_psw.mask = extract_psw_mask() | BIT(63 - 12);
+	mb();
+
+	/* cause a pgm int */
+	*((int *)-4) = 0x42;
+	mb();
+
+	report_fail("survived pgmint loop");
+
+	report_prefix_pop();
+	return report_summary();
+}
diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg
index 7d408f2d5310..c3073bfc4363 100644
--- a/s390x/unittests.cfg
+++ b/s390x/unittests.cfg
@@ -188,3 +188,7 @@ groups = migration
 [extint-loop]
 file = extint-loop.elf
 groups = panic
+
+[pgmint-loop]
+file = pgmint-loop.elf
+groups = panic
-- 
2.36.1