[PATCH 1/6] KVM: s390: selftests: Add kvm_exit test for instruction intercepts

["Aaron M. Brown" <aaronmbr@linux.ibm.com>]

Add a selftest for the exits KVM reports to userspace on s390x, mainly
KVM_EXIT_S390_SIEIC. This patch adds the harness and the instruction
intercept tests:

- DIAG 0x500: inject an external call, check it is pending, resume, and
  compare the registers with those synced in kvm_run.
- DIAG 0x501: check the opcode and diagnose code in ipa and ipb.
- DIAG 0x501 with registers set beforehand: check they are intact.

Co-developed-by: Nitya Khamar <nkhamar@linux.ibm.com>
Signed-off-by: Nitya Khamar <nkhamar@linux.ibm.com>
Signed-off-by: Aaron M. Brown <aaronmbr@linux.ibm.com>
---
 tools/testing/selftests/kvm/Makefile.kvm      |   1 +
 .../kvm/include/s390/kvm_lifecycle.h          |  35 +++
 tools/testing/selftests/kvm/s390/kvm_exit.c   | 212 ++++++++++++++++++
 3 files changed, 248 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/include/s390/kvm_lifecycle.h
 create mode 100644 tools/testing/selftests/kvm/s390/kvm_exit.c

diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm
index 17a4256e9081..a46a75c90e66 100644
--- a/tools/testing/selftests/kvm/Makefile.kvm
+++ b/tools/testing/selftests/kvm/Makefile.kvm
@@ -232,6 +232,7 @@ TEST_GEN_PROGS_s390 += s390/irq_routing
 TEST_GEN_PROGS_s390 += mmu_stress_test
 TEST_GEN_PROGS_s390 += pre_fault_memory_test
 TEST_GEN_PROGS_s390 += s390/irq_injection
+TEST_GEN_PROGS_s390 += s390/kvm_exit
 
 TEST_GEN_PROGS_riscv = $(TEST_GEN_PROGS_COMMON)
 TEST_GEN_PROGS_riscv += riscv/sbi_pmu_test
diff --git a/tools/testing/selftests/kvm/include/s390/kvm_lifecycle.h b/tools/testing/selftests/kvm/include/s390/kvm_lifecycle.h
new file mode 100644
index 000000000000..7dec11a6e214
--- /dev/null
+++ b/tools/testing/selftests/kvm/include/s390/kvm_lifecycle.h
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Definition of structs for KVM lifecycle tests.
+ *
+ * Copyright IBM Corp. 2026
+ *
+ * Authors:
+ *  Nitya Khamar (nkhamar@linux.ibm.com)
+ *  Aaron Malik Brown (aaronmbr@linux.ibm.com)
+ */
+#ifndef SELFTEST_KVM_LIFECYCLE_H
+#define SELFTEST_KVM_LIFECYCLE_H
+
+#include "kvm_util.h"
+#include <stdbool.h>
+
+struct kvm_lifecycle_testdef {
+	const char *name;
+	bool (*test)(void);
+};
+
+struct kvm_parameters {
+	struct kvm_vm *vm;
+	struct kvm_vcpu *vcpu;
+	void *guest_code;
+	struct kvm_run *run;
+	unsigned int interrupt_type;
+	struct kvm_s390_irq *irq;
+	struct kvm_s390_irq_state *irq_state;
+	struct {
+		bool immediate_exit_condition;
+	} manual_parameters;
+};
+
+#endif /* SELFTEST_KVM_LIFECYCLE_H */
diff --git a/tools/testing/selftests/kvm/s390/kvm_exit.c b/tools/testing/selftests/kvm/s390/kvm_exit.c
new file mode 100644
index 000000000000..140358357c67
--- /dev/null
+++ b/tools/testing/selftests/kvm/s390/kvm_exit.c
@@ -0,0 +1,212 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Test for KVM Exits to userspace on s390x
+ *
+ * Copyright IBM Corp. 2026
+ *
+ * Authors:
+ *  Nitya Khamar <nkhamar@linux.ibm.com>
+ *  Aaron Malik Brown <aaronmbr@linux.ibm.com>
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include "test_util.h"
+#include "kvm_util.h"
+#include "kselftest.h"
+#include <errno.h>
+#include "processor.h"
+#include "ucall_common.h"
+#include "sie.h"
+#include "kvm_lifecycle.h"
+
+#define NUM_GPRS 16
+#define DIAG_ASSEMBLY_CODE 0x501
+#define IPA_DIAG 0x83
+
+static struct kvm_parameters create_vm_kvm_exit(struct kvm_parameters parameters)
+{
+	parameters.vm = vm_create_with_one_vcpu(&parameters.vcpu,
+						parameters.guest_code);
+	return parameters;
+}
+
+static void cleanup_kvm(struct kvm_parameters *parameters)
+{
+	kvm_vm_free(parameters->vm);
+}
+
+static void compare_regs(struct kvm_regs *regs, struct kvm_sync_regs *sregs)
+{
+	int register_number;
+
+	for (register_number = 0; register_number < NUM_GPRS; register_number++)
+		TEST_ASSERT_EQ(regs->gprs[register_number], sregs->gprs[register_number]);
+}
+
+static void guestcode_instruction_intercept(void)
+{
+	asm volatile("diag 0,0, 0x500\n" :::);
+	GUEST_DONE();
+}
+
+static bool test_instruction_intercept(void)
+{
+	struct kvm_parameters param = {
+		.guest_code = guestcode_instruction_intercept,
+		.interrupt_type = KVM_S390_INT_EXTERNAL_CALL,
+		.manual_parameters.immediate_exit_condition = false,
+	};
+	struct kvm_s390_irq_state irq_state = {};
+	struct kvm_s390_irq irq = {};
+	struct kvm_regs regs;
+	int interrupts;
+
+	ksft_print_msg("Testing Instruction Intercept Exit\n");
+	param = create_vm_kvm_exit(param);
+	vcpu_run(param.vcpu);
+	param.run = param.vcpu->run;
+	irq.type = param.interrupt_type;
+	irq.u.extcall.code = param.vcpu->id;
+	irq_state.len = sizeof(irq);
+	irq_state.buf = (unsigned long)&irq;
+	param.irq = &irq;
+	param.irq_state = &irq_state;
+	TEST_ASSERT_KVM_EXIT_REASON(param.vcpu, KVM_EXIT_S390_SIEIC);
+	TEST_ASSERT(param.run->s390_sieic.icptcode == ICPT_INST,
+		    "Failed with Unexpected icptcode of 0x%x\n",
+		    param.run->s390_sieic.icptcode);
+	interrupts = __vcpu_ioctl(param.vcpu, KVM_S390_SET_IRQ_STATE,
+				  param.irq_state);
+	TEST_ASSERT(interrupts >= 0, "Cannot Inject Interrupt (%d)", errno);
+	irq_state.buf = (unsigned long)&irq;
+	irq_state.len = sizeof(irq);
+	interrupts = __vcpu_ioctl(param.vcpu, KVM_S390_GET_IRQ_STATE,
+				  &irq_state);
+	TEST_ASSERT(interrupts > 0,
+		    "Expected pending interrupt after injection, got %d", interrupts);
+	TEST_ASSERT_EQ(irq.type, KVM_S390_INT_EXTERNAL_CALL);
+	TEST_ASSERT_EQ(irq.u.extcall.code, param.vcpu->id);
+	vcpu_run(param.vcpu);
+	TEST_ASSERT_KVM_EXIT_REASON(param.vcpu, KVM_EXIT_S390_SIEIC);
+	TEST_ASSERT(param.run->s390_sieic.icptcode == ICPT_INST,
+		    "Expected ICPT_INST from GUEST_DONE after inject, got 0x%x\n",
+		    param.run->s390_sieic.icptcode);
+	vcpu_regs_get(param.vcpu, &regs);
+	compare_regs(&regs, &param.run->s.regs);
+	cleanup_kvm(&param);
+	return true;
+}
+
+static void guestcode_diagnose_hypercall(void)
+{
+	asm volatile("diag 0,0, 0x501\n" :::);
+}
+
+static bool test_diagnose_code(void)
+{
+	struct kvm_parameters param = {
+		.guest_code = guestcode_diagnose_hypercall,
+		.manual_parameters.immediate_exit_condition = false,
+	};
+	ksft_print_msg("Testing Diagnosis Hypercall Exit\n");
+	param = create_vm_kvm_exit(param);
+	vcpu_run(param.vcpu);
+	param.run = param.vcpu->run;
+	TEST_ASSERT_KVM_EXIT_REASON(param.vcpu, KVM_EXIT_S390_SIEIC);
+	TEST_ASSERT(param.run->s390_sieic.icptcode == ICPT_INST,
+		    "Failed with Unexpected Exit Reason of %u and icptcode of 0x%x\n",
+		    param.run->exit_reason, param.run->s390_sieic.icptcode);
+	TEST_ASSERT(param.run->s390_sieic.ipa >> 8 == IPA_DIAG,
+		    "Failed with Unexpected Opcode of %u\n",
+		    param.run->s390_sieic.ipa >> 8);
+	TEST_ASSERT(param.run->s390_sieic.ipb >> 16 == DIAG_ASSEMBLY_CODE,
+		    "Failed with Unexpected Diagnose Code of %u\n",
+		    param.run->s390_sieic.ipb >> 16);
+	cleanup_kvm(&param);
+	return true;
+}
+
+static void guestcode_diagnose_conditional(void)
+{
+	asm volatile("lghi %%r3,0x3333\n"
+		"lghi %%r5, 0x555\n"
+		"lghi %%r6, 0x3333\n"
+		"cgrjne %%r6, %%r3, 1f\n"
+		"diag 0,0, 0x501\n"
+		"1:\n"
+		:
+		:
+		: "r3", "r5", "r6"
+	);
+	GUEST_DONE();
+}
+
+static bool test_diagnose_conditional_code(void)
+{
+	struct kvm_parameters param = {
+		.guest_code = guestcode_diagnose_conditional,
+		.manual_parameters.immediate_exit_condition = false,
+	};
+	struct kvm_regs regs;
+
+	ksft_print_msg("Testing Diagnosis Hypercall for Conditional Code Exit\n");
+	param = create_vm_kvm_exit(param);
+	vcpu_run(param.vcpu);
+	param.run = param.vcpu->run;
+	TEST_ASSERT_KVM_EXIT_REASON(param.vcpu, KVM_EXIT_S390_SIEIC);
+	TEST_ASSERT(param.run->s390_sieic.icptcode == ICPT_INST,
+		    "Failed with Unexpected Exit Reason of %u and icptcode of 0x%x\n",
+		    param.run->exit_reason, param.run->s390_sieic.icptcode);
+	TEST_ASSERT(param.run->s390_sieic.ipa >> 8 == IPA_DIAG,
+		    "Failed with Unexpected Opcode of %u\n",
+		    param.run->s390_sieic.ipa >> 8);
+	TEST_ASSERT(param.run->s390_sieic.ipb >> 16 == DIAG_ASSEMBLY_CODE,
+		    "Failed with Unexpected Diagnose Code of %u\n",
+		    param.run->s390_sieic.ipb >> 16);
+	vcpu_regs_get(param.vcpu, &regs);
+	TEST_ASSERT_EQ(regs.gprs[3], 0x3333);
+	TEST_ASSERT_EQ(regs.gprs[5], 0x555);
+	TEST_ASSERT_EQ(regs.gprs[6], 0x3333);
+	cleanup_kvm(&param);
+	return true;
+}
+
+static void test(void)
+{
+	int i;
+	struct kvm_lifecycle_testdef testlist[] = {
+		{
+			.name = "Testing Instruction Intercepts",
+			.test = test_instruction_intercept,
+		},
+		{
+			.name = "Testing DIAG Code",
+			.test = test_diagnose_code,
+		},
+		{
+			.name = "Testing Conditional DIAG Code",
+			.test = test_diagnose_conditional_code,
+		},
+	};
+
+	ksft_print_header();
+	ksft_set_plan(ARRAY_SIZE(testlist));
+
+	for (i = 0; i < ARRAY_SIZE(testlist); i++) {
+		if (testlist[i].test())
+			ksft_test_result_pass("%s\n", testlist[i].name);
+		else
+			ksft_test_result_skip("%s\n", testlist[i].name);
+	}
+}
+
+int main(void)
+{
+	TEST_REQUIRE(kvm_has_cap(KVM_CAP_USER_MEMORY2));
+	TEST_REQUIRE(kvm_has_cap(KVM_CAP_SYNC_REGS));
+	test();
+	ksft_finished();
+}
-- 
2.50.1 (Apple Git-155)