[PATCH 03/10] selftests: KVM: Introduce system_counter_state_test

[Oliver Upton <oupton@google.com>]

Test that the KVM_{GET,SET}_SYSTEM_COUNTER_STATE ioctls correctly
configure the guest's view of the virtual counter-timer (CNTVCT_EL0).

Reviewed-by: Jing Zhang <jingzhangos@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Peter Shier <pshier@google.com>
Reviewed-by: Ricardo Koller <ricarkol@google.com>
Signed-off-by: Oliver Upton <oupton@google.com>
---
 tools/testing/selftests/kvm/.gitignore        |   1 +
 tools/testing/selftests/kvm/Makefile          |   1 +
 .../selftests/kvm/include/aarch64/processor.h |  24 +++
 .../selftests/kvm/system_counter_state_test.c | 199 ++++++++++++++++++
 4 files changed, 225 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/system_counter_state_test.c

diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index bd83158e0e0b..1a5782d8a0d4 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -34,6 +34,7 @@
 /x86_64/xen_vmcall_test
 /x86_64/xss_msr_test
 /x86_64/vmx_pmu_msrs_test
+/system_counter_state_test
 /demand_paging_test
 /dirty_log_test
 /dirty_log_perf_test
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index e439d027939d..b14f16dc954a 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -80,6 +80,7 @@ TEST_GEN_PROGS_x86_64 += steal_time
 TEST_GEN_PROGS_aarch64 += aarch64/get-reg-list
 TEST_GEN_PROGS_aarch64 += aarch64/get-reg-list-sve
 TEST_GEN_PROGS_aarch64 += aarch64/vgic_init
+TEST_GEN_PROGS_aarch64 += system_counter_state_test
 TEST_GEN_PROGS_aarch64 += demand_paging_test
 TEST_GEN_PROGS_aarch64 += dirty_log_test
 TEST_GEN_PROGS_aarch64 += dirty_log_perf_test
diff --git a/tools/testing/selftests/kvm/include/aarch64/processor.h b/tools/testing/selftests/kvm/include/aarch64/processor.h
index b7fa0c8551db..48c964ce62ff 100644
--- a/tools/testing/selftests/kvm/include/aarch64/processor.h
+++ b/tools/testing/selftests/kvm/include/aarch64/processor.h
@@ -52,6 +52,30 @@ static inline void set_reg(struct kvm_vm *vm, uint32_t vcpuid, uint64_t id, uint
 	vcpu_ioctl(vm, vcpuid, KVM_SET_ONE_REG, &reg);
 }
 
+static inline uint64_t read_cntpct_ordered(void)
+{
+	uint64_t r;
+
+	asm volatile("isb\n\t"
+		     "mrs %0, cntpct_el0\n\t"
+		     "isb\n\t"
+		     : "=r"(r));
+
+	return r;
+}
+
+static inline uint64_t read_cntvct_ordered(void)
+{
+	uint64_t r;
+
+	asm volatile("isb\n\t"
+		     "mrs %0, cntvct_el0\n\t"
+		     "isb\n\t"
+		     : "=r"(r));
+
+	return r;
+}
+
 void aarch64_vcpu_setup(struct kvm_vm *vm, int vcpuid, struct kvm_vcpu_init *init);
 void aarch64_vcpu_add_default(struct kvm_vm *vm, uint32_t vcpuid,
 			      struct kvm_vcpu_init *init, void *guest_code);
diff --git a/tools/testing/selftests/kvm/system_counter_state_test.c b/tools/testing/selftests/kvm/system_counter_state_test.c
new file mode 100644
index 000000000000..059971f6cb87
--- /dev/null
+++ b/tools/testing/selftests/kvm/system_counter_state_test.c
@@ -0,0 +1,199 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * system_counter_state_test.c -- suite of tests for correctness of
+ * KVM_{GET,SET}_SYSTEM_COUNTER_STATE ioctls.
+ *
+ * Copyright (c) 2021, Google LLC.
+ */
+#define _GNU_SOURCE
+#include <asm/kvm.h>
+#include <linux/kvm.h>
+#include <stdint.h>
+
+#include "kvm_util.h"
+#include "processor.h"
+#include "test_util.h"
+
+#define VCPU_ID 0
+
+#ifdef __aarch64__
+
+enum counter {
+	VIRTUAL,
+	PHYSICAL,
+};
+
+static char *counter_name(enum counter counter)
+{
+	switch (counter) {
+	case VIRTUAL:
+		return "virtual";
+	case PHYSICAL:
+		return "physical";
+	default:
+		TEST_ASSERT(false, "unrecognized counter: %d", counter);
+	}
+
+	/* never reached */
+	return NULL;
+}
+
+struct system_counter_state_test {
+	enum counter counter;
+	struct kvm_system_counter_state state;
+};
+
+static struct system_counter_state_test test_cases[] = {
+	{
+		.counter = VIRTUAL,
+		.state = {
+			.cntvoff = 0
+		}
+	},
+	{
+		.counter = VIRTUAL,
+		.state = {
+			.cntvoff = 1000000
+		}
+	},
+	{
+		.counter = VIRTUAL,
+		.state = {
+			.cntvoff = -1
+		}
+	},
+};
+
+static void pr_test(struct system_counter_state_test *test)
+{
+	pr_info("counter: %s, cntvoff: %lld\n", counter_name(test->counter), test->state.cntvoff);
+}
+
+static struct kvm_system_counter_state *
+get_system_counter_state(struct system_counter_state_test *test)
+{
+	return &test->state;
+}
+
+/*
+ * Reads the guest counter-timer under test.
+ */
+static uint64_t guest_read_counter(struct system_counter_state_test *test)
+{
+	switch (test->counter) {
+	case PHYSICAL:
+		return read_cntpct_ordered();
+	case VIRTUAL:
+		return read_cntvct_ordered();
+	default:
+		GUEST_ASSERT(0);
+	}
+
+	/* never reached */
+	return -1;
+}
+
+/*
+ * Reads the host physical counter-timer and transforms it into a guest value
+ * according to the kvm_system_counter_state structure.
+ */
+static uint64_t host_read_guest_counter(struct system_counter_state_test *test)
+{
+	uint64_t r;
+
+	r = read_cntvct_ordered();
+	switch (test->counter) {
+	case VIRTUAL:
+		r -= test->state.cntvoff;
+		break;
+	default:
+		TEST_ASSERT(false, "unrecognized counter: %d", test->counter);
+	}
+
+	return r;
+}
+
+#else
+#error test not implemented for architecture being built!
+#endif
+
+static void guest_main(void)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(test_cases); i++) {
+		struct system_counter_state_test *test = &test_cases[i];
+
+		GUEST_SYNC(guest_read_counter(test));
+	}
+
+	GUEST_DONE();
+}
+
+static bool enter_guest(struct kvm_vm *vm, uint64_t *guest_counter)
+{
+	struct ucall uc;
+
+	vcpu_ioctl(vm, VCPU_ID, KVM_RUN, NULL);
+
+	switch (get_ucall(vm, VCPU_ID, &uc)) {
+	case UCALL_DONE:
+		return true;
+	case UCALL_SYNC:
+		if (guest_counter)
+			*guest_counter = uc.args[1];
+		break;
+	case UCALL_ABORT:
+		TEST_ASSERT(false, "%s at %s:%ld", (const char *)uc.args[0],
+			    __FILE__, uc.args[1]);
+		break;
+	default:
+		TEST_ASSERT(false, "unexpected exit: %s",
+			    exit_reason_str(vcpu_state(vm, VCPU_ID)->exit_reason));
+		break;
+	}
+
+	/* more work to do in the guest */
+	return false;
+}
+
+static void run_tests(struct kvm_vm *vm)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(test_cases); i++) {
+		struct system_counter_state_test *test = &test_cases[i];
+		uint64_t start, end, obs;
+
+		pr_info("test %d: ", i);
+		pr_test(test);
+
+		vcpu_ioctl(vm, VCPU_ID, KVM_SET_SYSTEM_COUNTER_STATE,
+			   get_system_counter_state(test));
+
+		start = host_read_guest_counter(test);
+		TEST_ASSERT(!enter_guest(vm, &obs), "guest completed unexpectedly");
+		end = host_read_guest_counter(test);
+
+		TEST_ASSERT(start < obs && obs < end,
+			    "guest counter value (%ld) outside expected bounds: (%ld, %ld)",
+			    obs, start, end);
+	}
+
+	TEST_ASSERT(enter_guest(vm, NULL), "guest didn't run to completion");
+}
+
+int main(void)
+{
+	struct kvm_vm *vm;
+
+	if (!kvm_check_cap(KVM_CAP_SYSTEM_COUNTER_STATE)) {
+		print_skip("KVM_CAP_SYSTEM_COUNTER_STATE not supported");
+		exit(KSFT_SKIP);
+	}
+
+	vm = vm_create_default(0, 0, guest_main);
+	ucall_init(vm, NULL);
+	run_tests(vm);
+	kvm_vm_free(vm);
+}
-- 
2.32.0.rc1.229.g3e70b5a671-goog