[kvm-unit-tests PATCH v1 2/2] s390x: add migration test for storage keys

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

Upon migration, we expect storage keys being set by the guest to be preserved,
so add a test for it.

We keep 128 pages and set predictable storage keys. Then, we migrate and check
they can be read back and the respective access restrictions are in place when
the access key in the PSW doesn't match.

TCG currently doesn't implement key-controlled protection, see
target/s390x/mmu_helper.c, function mmu_handle_skey(), hence add the relevant
tests as xfails.

Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
---
 s390x/Makefile         |  1 +
 s390x/migration-skey.c | 98 ++++++++++++++++++++++++++++++++++++++++++
 s390x/unittests.cfg    |  4 ++
 3 files changed, 103 insertions(+)
 create mode 100644 s390x/migration-skey.c

diff --git a/s390x/Makefile b/s390x/Makefile
index a8e04aa6fe4d..f8ea594b641d 100644
--- a/s390x/Makefile
+++ b/s390x/Makefile
@@ -32,6 +32,7 @@ tests += $(TEST_DIR)/epsw.elf
 tests += $(TEST_DIR)/adtl-status.elf
 tests += $(TEST_DIR)/migration.elf
 tests += $(TEST_DIR)/pv-attest.elf
+tests += $(TEST_DIR)/migration-skey.elf
 
 pv-tests += $(TEST_DIR)/pv-diags.elf
 
diff --git a/s390x/migration-skey.c b/s390x/migration-skey.c
new file mode 100644
index 000000000000..6f3053d8ab40
--- /dev/null
+++ b/s390x/migration-skey.c
@@ -0,0 +1,98 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Storage Key migration tests
+ *
+ * Copyright IBM Corp. 2022
+ *
+ * Authors:
+ *  Nico Boehr <nrb@linux.ibm.com>
+ */
+
+#include <libcflat.h>
+#include <asm/facility.h>
+#include <asm/page.h>
+#include <asm/mem.h>
+#include <asm/interrupt.h>
+#include <hardware.h>
+
+#define NUM_PAGES 128
+static uint8_t pagebuf[NUM_PAGES][PAGE_SIZE] __attribute__((aligned(PAGE_SIZE)));
+
+static void test_migration(void)
+{
+	int i, key_to_set;
+	uint8_t *page;
+	union skey expected_key, actual_key, mismatching_key;
+
+	for (i = 0; i < NUM_PAGES; i++) {
+		/*
+		 * Storage keys are 7 bit, lowest bit is always returned as zero
+		 * by iske
+		 */
+		key_to_set = i * 2;
+		set_storage_key(pagebuf + i, key_to_set, 1);
+	}
+
+	puts("Please migrate me, then press return\n");
+	(void)getchar();
+
+	for (i = 0; i < NUM_PAGES; i++) {
+		report_prefix_pushf("page %d", i);
+
+		page = &pagebuf[i][0];
+		actual_key.val = get_storage_key(page);
+		expected_key.val = i * 2;
+
+		/* ignore reference bit */
+		actual_key.str.rf = 0;
+		expected_key.str.rf = 0;
+
+		report(actual_key.val == expected_key.val, "expected_key=0x%x actual_key=0x%x", expected_key.val, actual_key.val);
+
+		/* ensure access key doesn't match storage key and is never zero */
+		mismatching_key.str.acc = expected_key.str.acc < 15 ? expected_key.str.acc + 1 : 1;
+		*page = 0xff;
+
+		expect_pgm_int();
+		asm volatile (
+			/* set access key */
+			"spka 0(%[mismatching_key])\n"
+			/* try to write page */
+			"mvi 0(%[page]), 42\n"
+			/* reset access key */
+			"spka 0\n"
+			:
+			: [mismatching_key] "a"(mismatching_key.val),
+			  [page] "a"(page)
+			: "memory"
+		);
+		check_pgm_int_code_xfail(host_is_tcg(), PGM_INT_CODE_PROTECTION);
+		report_xfail(host_is_tcg(), *page == 0xff, "no store occured");
+
+		report_prefix_pop();
+	}
+}
+
+int main(void)
+{
+	report_prefix_push("migration-skey");
+	if (test_facility(169)) {
+		report_skip("storage key removal facility is active");
+
+		/*
+		 * If we just exit and don't ask migrate_cmd to migrate us, it
+		 * will just hang forever. Hence, also ask for migration when we
+		 * skip this test alltogether.
+		 */
+		puts("Please migrate me, then press return\n");
+		(void)getchar();
+
+		goto done;
+	}
+
+	test_migration();
+
+done:
+	report_prefix_pop();
+	return report_summary();
+}
diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg
index b456b2881448..1e851d8e3dd8 100644
--- a/s390x/unittests.cfg
+++ b/s390x/unittests.cfg
@@ -176,3 +176,7 @@ extra_params = -cpu qemu,gs=off,vx=off
 file = migration.elf
 groups = migration
 smp = 2
+
+[migration-skey]
+file = migration-skey.elf
+groups = migration
-- 
2.31.1