[kvm-unit-tests PATCH v3 1/8] s390x: Add more tests for MSCH

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

We already have some coverage for MSCH, but there are more cases to test
for:

- invalid SCHIB structure. We cover that by setting reserved bits 0, 1,
  6 and 7 in the flags of the PMCW.
  Older QEMU versions require this bit to always be zero on msch,
  which is why this test may fail. A fix is available in QEMU master
  commit 2df59b73e086 ("s390x/css: fix PMCW invalid mask").
- a pointer to an unaligned SCHIB. We cover misalignment by 1
  and 2 bytes. Using pointer to valid memory avoids messing up
  random memory in case of test failures.

Here's the QEMU PMCW invalid mask fix: https://lists.nongnu.org/archive/html/qemu-s390x/2021-12/msg00100.html

Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
---
 s390x/css.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/s390x/css.c b/s390x/css.c
index 881206ba1cef..932daf69bb36 100644
--- a/s390x/css.c
+++ b/s390x/css.c
@@ -27,6 +27,8 @@ static int test_device_sid;
 static struct senseid *senseid;
 struct ccw1 *ccw;
 
+char alignment_test_page[PAGE_SIZE] __attribute__((aligned(PAGE_SIZE)));
+
 static void test_enumerate(void)
 {
 	test_device_sid = css_enumerate();
@@ -331,6 +333,56 @@ static void test_schm_fmt1(void)
 	free_io_mem(mb1, sizeof(struct measurement_block_format1));
 }
 
+static void test_msch(void)
+{
+	const int align_to = 4;
+	int cc;
+	int invalid_pmcw_flags[] = {0, 1, 6, 7};
+	int invalid_flag;
+	uint16_t old_pmcw_flags;
+
+	if (!test_device_sid) {
+		report_skip("No device");
+		return;
+	}
+
+	cc = stsch(test_device_sid, &schib);
+	if (cc) {
+		report_fail("stsch: sch %08x failed with cc=%d", test_device_sid, cc);
+		return;
+	}
+
+	report_prefix_push("Unaligned");
+	for (int i = 1; i < align_to; i *= 2) {
+		report_prefix_pushf("%d", i);
+
+		expect_pgm_int();
+		msch(test_device_sid, (struct schib *)(alignment_test_page + i));
+		check_pgm_int_code(PGM_INT_CODE_SPECIFICATION);
+
+		report_prefix_pop();
+	}
+	report_prefix_pop();
+
+	report_prefix_push("Invalid SCHIB");
+	old_pmcw_flags = schib.pmcw.flags;
+	for (int i = 0; i < ARRAY_SIZE(invalid_pmcw_flags); i++) {
+		invalid_flag = invalid_pmcw_flags[i];
+
+		report_prefix_pushf("PMCW flag bit %d set", invalid_flag);
+
+		schib.pmcw.flags = old_pmcw_flags | BIT(15 - invalid_flag);
+		expect_pgm_int();
+		msch(test_device_sid, &schib);
+		check_pgm_int_code(PGM_INT_CODE_OPERAND);
+
+		report_prefix_pop();
+	}
+	report_prefix_pop();
+
+	schib.pmcw.flags = old_pmcw_flags;
+}
+
 static struct {
 	const char *name;
 	void (*func)(void);
@@ -343,6 +395,7 @@ static struct {
 	{ "measurement block (schm)", test_schm },
 	{ "measurement block format0", test_schm_fmt0 },
 	{ "measurement block format1", test_schm_fmt1 },
+	{ "msch", test_msch },
 	{ NULL, NULL }
 };
 
-- 
2.31.1