[PATCH v6 15/21] selftests: KVM: Add support for aarch64 to system_counter_offset_test

[Oliver Upton <oupton@xxxxxxxxxx>]

KVM/arm64 now allows userspace to adjust the guest virtual counter-timer
via a vCPU register. Test that changes to the virtual counter-timer
offset result in the correct view being presented to the guest.

Reviewed-by: Andrew Jones <drjones@xxxxxxxxxx>
Signed-off-by: Oliver Upton <oupton@xxxxxxxxxx>
---
 tools/testing/selftests/kvm/Makefile          |  1 +
 .../selftests/kvm/include/aarch64/processor.h | 12 ++++
 .../kvm/system_counter_offset_test.c          | 56 ++++++++++++++++++-
 3 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 9f7060c02668..fab42e7c23ee 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -98,6 +98,7 @@ TEST_GEN_PROGS_aarch64 += kvm_page_table_test
 TEST_GEN_PROGS_aarch64 += set_memory_region_test
 TEST_GEN_PROGS_aarch64 += steal_time
 TEST_GEN_PROGS_aarch64 += kvm_binary_stats_test
+TEST_GEN_PROGS_aarch64 += system_counter_offset_test
 
 TEST_GEN_PROGS_s390x = s390x/memop
 TEST_GEN_PROGS_s390x += s390x/resets
diff --git a/tools/testing/selftests/kvm/include/aarch64/processor.h b/tools/testing/selftests/kvm/include/aarch64/processor.h
index 27dc5c2e56b9..3168cdbae6ee 100644
--- a/tools/testing/selftests/kvm/include/aarch64/processor.h
+++ b/tools/testing/selftests/kvm/include/aarch64/processor.h
@@ -129,4 +129,16 @@ void vm_install_sync_handler(struct kvm_vm *vm,
 
 #define isb()	asm volatile("isb" : : : "memory")
 
+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;
+}
+
 #endif /* SELFTEST_KVM_PROCESSOR_H */
diff --git a/tools/testing/selftests/kvm/system_counter_offset_test.c b/tools/testing/selftests/kvm/system_counter_offset_test.c
index b337bbbfa41f..ac933db83d03 100644
--- a/tools/testing/selftests/kvm/system_counter_offset_test.c
+++ b/tools/testing/selftests/kvm/system_counter_offset_test.c
@@ -53,7 +53,61 @@ static uint64_t host_read_guest_system_counter(struct test_case *test)
 	return rdtsc() + test->tsc_offset;
 }
 
-#else /* __x86_64__ */
+#elif __aarch64__ /* __x86_64__ */
+
+enum arch_counter {
+	VIRTUAL,
+};
+
+struct test_case {
+	enum arch_counter counter;
+	uint64_t offset;
+};
+
+static struct test_case test_cases[] = {
+	{ .counter = VIRTUAL, .offset = 0 },
+	{ .counter = VIRTUAL, .offset = 180 * NSEC_PER_SEC },
+	{ .counter = VIRTUAL, .offset = -180 * NSEC_PER_SEC },
+};
+
+static void check_preconditions(struct kvm_vm *vm)
+{
+	if (vcpu_has_reg(vm, VCPU_ID, KVM_REG_ARM_TIMER_OFFSET))
+		return;
+
+	print_skip("KVM_REG_ARM_TIMER_OFFSET not supported; skipping test");
+	exit(KSFT_SKIP);
+}
+
+static void setup_system_counter(struct kvm_vm *vm, struct test_case *test)
+{
+	struct kvm_one_reg reg = {
+		.id = KVM_REG_ARM_TIMER_OFFSET,
+		.addr = (__u64)&test->offset,
+	};
+
+	vcpu_set_reg(vm, VCPU_ID, &reg);
+}
+
+static uint64_t guest_read_system_counter(struct test_case *test)
+{
+	switch (test->counter) {
+	case VIRTUAL:
+		return read_cntvct_ordered();
+	default:
+		GUEST_ASSERT(0);
+	}
+
+	/* unreachable */
+	return 0;
+}
+
+static uint64_t host_read_guest_system_counter(struct test_case *test)
+{
+	return read_cntvct_ordered() - test->offset;
+}
+
+#else /* __aarch64__ */
 
 #error test not implemented for this architecture!
 
-- 
2.32.0.605.g8dce9f2422-goog

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