tools/testing/selftests/kvm/system_counter_offset_test.c

Source file repositories/reference/linux-study-clean/tools/testing/selftests/kvm/system_counter_offset_test.c

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/kvm/system_counter_offset_test.c
Extension
.c
Size
2626 bytes
Lines
128
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

struct test_case {
	u64 tsc_offset;
};

static struct test_case test_cases[] = {
	{ 0 },
	{ 180 * NSEC_PER_SEC },
	{ -180 * NSEC_PER_SEC },
};

static void check_preconditions(struct kvm_vcpu *vcpu)
{
	__TEST_REQUIRE(!__vcpu_has_device_attr(vcpu, KVM_VCPU_TSC_CTRL,
					       KVM_VCPU_TSC_OFFSET),
		       "KVM_VCPU_TSC_OFFSET not supported; skipping test");
}

static void setup_system_counter(struct kvm_vcpu *vcpu, struct test_case *test)
{
	vcpu_device_attr_set(vcpu, KVM_VCPU_TSC_CTRL, KVM_VCPU_TSC_OFFSET,
			     &test->tsc_offset);
}

static u64 guest_read_system_counter(struct test_case *test)
{
	return rdtsc();
}

static u64 host_read_guest_system_counter(struct test_case *test)
{
	return rdtsc() + test->tsc_offset;
}

#else /* __x86_64__ */

#error test not implemented for this architecture!

#endif

#define GUEST_SYNC_CLOCK(__stage, __val)			\
		GUEST_SYNC_ARGS(__stage, __val, 0, 0, 0)

static void guest_main(void)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(test_cases); i++) {
		struct test_case *test = &test_cases[i];

		GUEST_SYNC_CLOCK(i, guest_read_system_counter(test));
	}
}

static void handle_sync(struct ucall *uc, u64 start, u64 end)
{
	u64 obs = uc->args[2];

	TEST_ASSERT(start <= obs && obs <= end,
		    "unexpected system counter value: %"PRIu64" expected range: [%"PRIu64", %"PRIu64"]",
		    obs, start, end);

	pr_info("system counter value: %"PRIu64" expected range [%"PRIu64", %"PRIu64"]\n",
		obs, start, end);
}

static void handle_abort(struct ucall *uc)
{
	REPORT_GUEST_ASSERT(*uc);
}

static void enter_guest(struct kvm_vcpu *vcpu)
{
	u64 start, end;
	struct ucall uc;
	int i;

	for (i = 0; i < ARRAY_SIZE(test_cases); i++) {
		struct test_case *test = &test_cases[i];

		setup_system_counter(vcpu, test);
		start = host_read_guest_system_counter(test);
		vcpu_run(vcpu);
		end = host_read_guest_system_counter(test);

		switch (get_ucall(vcpu, &uc)) {
		case UCALL_SYNC:
			handle_sync(&uc, start, end);
			break;
		case UCALL_ABORT:
			handle_abort(&uc);

Annotation

Implementation Notes