[PATCH v4 6/6] KVM: s390: selftests: Add selftest for single-stepping

[Ilya Leoshkevich <iii@linux.ibm.com>]

Test different variations of single-stepping into interrupts:

- SVC and PGM interrupts;
- Interrupts generated by ISKE;
- Interrupts generated by instructions emulated by KVM;
- Interrupts generated by instructions emulated by userspace.

Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 tools/testing/selftests/kvm/Makefile          |   1 +
 .../testing/selftests/kvm/s390x/debug_test.c  | 160 ++++++++++++++++++
 2 files changed, 161 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/s390x/debug_test.c

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index c692cc86e7da..f3306eaa7031 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -166,6 +166,7 @@ TEST_GEN_PROGS_s390x += s390x/resets
 TEST_GEN_PROGS_s390x += s390x/sync_regs_test
 TEST_GEN_PROGS_s390x += s390x/tprot
 TEST_GEN_PROGS_s390x += s390x/cmma_test
+TEST_GEN_PROGS_s390x += s390x/debug_test
 TEST_GEN_PROGS_s390x += demand_paging_test
 TEST_GEN_PROGS_s390x += dirty_log_test
 TEST_GEN_PROGS_s390x += kvm_create_max_vcpus
diff --git a/tools/testing/selftests/kvm/s390x/debug_test.c b/tools/testing/selftests/kvm/s390x/debug_test.c
new file mode 100644
index 000000000000..a8fa9fe93b3c
--- /dev/null
+++ b/tools/testing/selftests/kvm/s390x/debug_test.c
@@ -0,0 +1,160 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Test KVM debugging features. */
+#include "kvm_util.h"
+#include "test_util.h"
+
+#include <linux/kvm.h>
+
+#define __LC_SVC_NEW_PSW 0x1c0
+#define __LC_PGM_NEW_PSW 0x1d0
+#define ICPT_INSTRUCTION 0x04
+#define IPA0_DIAG 0x8300
+#define PGM_SPECIFICATION 0x06
+
+/* Common code for testing single-stepping interruptions. */
+extern char int_handler[];
+asm("int_handler:\n"
+    "j .\n");
+
+static struct kvm_vm *test_step_int_1(struct kvm_vcpu **vcpu, void *guest_code,
+				      size_t new_psw_off, uint64_t *new_psw)
+{
+	struct kvm_guest_debug debug = {};
+	struct kvm_regs regs;
+	struct kvm_vm *vm;
+	char *lowcore;
+
+	vm = vm_create_with_one_vcpu(vcpu, guest_code);
+	lowcore = addr_gpa2hva(vm, 0);
+	new_psw[0] = (*vcpu)->run->psw_mask;
+	new_psw[1] = (uint64_t)int_handler;
+	memcpy(lowcore + new_psw_off, new_psw, 16);
+	vcpu_regs_get(*vcpu, &regs);
+	regs.gprs[2] = -1;
+	vcpu_regs_set(*vcpu, &regs);
+	debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_SINGLESTEP;
+	vcpu_guest_debug_set(*vcpu, &debug);
+	vcpu_run(*vcpu);
+
+	return vm;
+}
+
+static void test_step_int(void *guest_code, size_t new_psw_off)
+{
+	struct kvm_vcpu *vcpu;
+	uint64_t new_psw[2];
+	struct kvm_vm *vm;
+
+	vm = test_step_int_1(&vcpu, guest_code, new_psw_off, new_psw);
+	TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_DEBUG);
+	ASSERT_EQ(vcpu->run->psw_mask, new_psw[0]);
+	ASSERT_EQ(vcpu->run->psw_addr, new_psw[1]);
+	kvm_vm_free(vm);
+}
+
+/* Test single-stepping "boring" program interruptions. */
+extern char test_step_pgm_guest_code[];
+asm("test_step_pgm_guest_code:\n"
+    ".insn rr,0x1d00,%r1,%r0 /* dr %r1,%r0 */\n"
+    "j .\n");
+
+static void test_step_pgm(void)
+{
+	test_step_int(test_step_pgm_guest_code, __LC_PGM_NEW_PSW);
+}
+
+/*
+ * Test single-stepping program interruptions caused by DIAG.
+ * Userspace emulation must not interfere with single-stepping.
+ */
+extern char test_step_pgm_diag_guest_code[];
+asm("test_step_pgm_diag_guest_code:\n"
+    "diag %r0,%r0,0\n"
+    "j .\n");
+
+static void test_step_pgm_diag(void)
+{
+	struct kvm_s390_irq irq = {
+		.type = KVM_S390_PROGRAM_INT,
+		.u.pgm.code = PGM_SPECIFICATION,
+	};
+	struct kvm_vcpu *vcpu;
+	uint64_t new_psw[2];
+	struct kvm_vm *vm;
+
+	vm = test_step_int_1(&vcpu, test_step_pgm_diag_guest_code,
+			     __LC_PGM_NEW_PSW, new_psw);
+	TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_S390_SIEIC);
+	ASSERT_EQ(vcpu->run->s390_sieic.icptcode, ICPT_INSTRUCTION);
+	ASSERT_EQ(vcpu->run->s390_sieic.ipa & 0xff00, IPA0_DIAG);
+	vcpu_ioctl(vcpu, KVM_S390_IRQ, &irq);
+	vcpu_run(vcpu);
+	TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_DEBUG);
+	ASSERT_EQ(vcpu->run->psw_mask, new_psw[0]);
+	ASSERT_EQ(vcpu->run->psw_addr, new_psw[1]);
+	kvm_vm_free(vm);
+}
+
+/*
+ * Test single-stepping program interruptions caused by ISKE.
+ * CPUSTAT_KSS handling must not interfere with single-stepping.
+ */
+extern char test_step_pgm_iske_guest_code[];
+asm("test_step_pgm_iske_guest_code:\n"
+    "iske %r2,%r2\n"
+    "j .\n");
+
+static void test_step_pgm_iske(void)
+{
+	test_step_int(test_step_pgm_iske_guest_code, __LC_PGM_NEW_PSW);
+}
+
+/*
+ * Test single-stepping program interruptions caused by LCTL.
+ * KVM emulation must not interfere with single-stepping.
+ */
+extern char test_step_pgm_lctl_guest_code[];
+asm("test_step_pgm_lctl_guest_code:\n"
+    "lctl %c0,%c0,1\n"
+    "j .\n");
+
+static void test_step_pgm_lctl(void)
+{
+	test_step_int(test_step_pgm_lctl_guest_code, __LC_PGM_NEW_PSW);
+}
+
+/* Test single-stepping supervisor-call interruptions. */
+extern char test_step_svc_guest_code[];
+asm("test_step_svc_guest_code:\n"
+    "svc 0\n"
+    "j .\n");
+
+static void test_step_svc(void)
+{
+	test_step_int(test_step_svc_guest_code, __LC_SVC_NEW_PSW);
+}
+
+/* Run all tests above. */
+static struct testdef {
+	const char *name;
+	void (*test)(void);
+} testlist[] = {
+	{ "single-step pgm", test_step_pgm },
+	{ "single-step pgm caused by diag", test_step_pgm_diag },
+	{ "single-step pgm caused by iske", test_step_pgm_iske },
+	{ "single-step pgm caused by lctl", test_step_pgm_lctl },
+	{ "single-step svc", test_step_svc },
+};
+
+int main(int argc, char *argv[])
+{
+	int idx;
+
+	ksft_print_header();
+	ksft_set_plan(ARRAY_SIZE(testlist));
+	for (idx = 0; idx < ARRAY_SIZE(testlist); idx++) {
+		testlist[idx].test();
+		ksft_test_result_pass("%s\n", testlist[idx].name);
+	}
+	ksft_finished();
+}
-- 
2.41.0