diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index 36896d251977..958a809c8de4 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -11,6 +11,7 @@
 /x86_64/emulator_error_test
 /x86_64/get_cpuid_test
 /x86_64/get_msr_index_features
+/x86_64/kvm_clock_test
 /x86_64/kvm_pv_test
 /x86_64/hyperv_clock
 /x86_64/hyperv_cpuid
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index c103873531e0..0f94b18b33ce 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -46,6 +46,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/get_cpuid_test
 TEST_GEN_PROGS_x86_64 += x86_64/hyperv_clock
 TEST_GEN_PROGS_x86_64 += x86_64/hyperv_cpuid
 TEST_GEN_PROGS_x86_64 += x86_64/hyperv_features
+TEST_GEN_PROGS_x86_64 += x86_64/kvm_clock_test
 TEST_GEN_PROGS_x86_64 += x86_64/kvm_pv_test
 TEST_GEN_PROGS_x86_64 += x86_64/mmio_warning_test
 TEST_GEN_PROGS_x86_64 += x86_64/mmu_role_test
diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index 010b59b13917..a8ac5d52e17b 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -19,6 +19,8 @@
 #define KVM_DEV_PATH "/dev/kvm"
 #define KVM_MAX_VCPUS 512
 
+#define NSEC_PER_SEC 1000000000L
+
 /*
  * Callers of kvm_util only have an incomplete/opaque description of the
  * structure kvm_util is using to maintain the state of a VM.
diff --git a/tools/testing/selftests/kvm/x86_64/kvm_clock_test.c b/tools/testing/selftests/kvm/x86_64/kvm_clock_test.c
new file mode 100644
index 000000000000..e0dcc27ae9f1
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/kvm_clock_test.c
@@ -0,0 +1,204 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2021, Google LLC.
+ *
+ * Tests for adjusting the KVM clock from userspace
+ */
+#include <asm/kvm_para.h>
+#include <asm/pvclock.h>
+#include <asm/pvclock-abi.h>
+#include <stdint.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <time.h>
+
+#include "test_util.h"
+#include "kvm_util.h"
+#include "processor.h"
+
+#define VCPU_ID 0
+
+struct test_case {
+	uint64_t kvmclock_base;
+	int64_t realtime_offset;
+};
+
+static struct test_case test_cases[] = {
+	{ .kvmclock_base = 0 },
+	{ .kvmclock_base = 180 * NSEC_PER_SEC },
+	{ .kvmclock_base = 0, .realtime_offset = -180 * NSEC_PER_SEC },
+	{ .kvmclock_base = 0, .realtime_offset = 180 * NSEC_PER_SEC },
+};
+
+#define GUEST_SYNC_CLOCK(__stage, __val)			\
+		GUEST_SYNC_ARGS(__stage, __val, 0, 0, 0)
+
+static void guest_main(vm_paddr_t pvti_pa, struct pvclock_vcpu_time_info *pvti)
+{
+	int i;
+
+	wrmsr(MSR_KVM_SYSTEM_TIME_NEW, pvti_pa | KVM_MSR_ENABLED);
+	for (i = 0; i < ARRAY_SIZE(test_cases); i++)
+		GUEST_SYNC_CLOCK(i, __pvclock_read_cycles(pvti, rdtsc()));
+}
+
+#define EXPECTED_FLAGS (KVM_CLOCK_REALTIME | KVM_CLOCK_HOST_TSC)
+
+static inline void assert_flags(struct kvm_clock_data *data)
+{
+	TEST_ASSERT((data->flags & EXPECTED_FLAGS) == EXPECTED_FLAGS,
+		    "unexpected clock data flags: %x (want set: %x)",
+		    data->flags, EXPECTED_FLAGS);
+}
+
+static void handle_sync(struct ucall *uc, struct kvm_clock_data *start,
+			struct kvm_clock_data *end)
+{
+	uint64_t obs, exp_lo, exp_hi;
+
+	obs = uc->args[2];
+	exp_lo = start->clock;
+	exp_hi = end->clock;
+
+	assert_flags(start);
+	assert_flags(end);
+
+	TEST_ASSERT(exp_lo <= obs && obs <= exp_hi,
+		    "unexpected kvm-clock value: %"PRIu64" expected range: [%"PRIu64", %"PRIu64"]",
+		    obs, exp_lo, exp_hi);
+
+	pr_info("kvm-clock value: %"PRIu64" expected range [%"PRIu64", %"PRIu64"]\n",
+		obs, exp_lo, exp_hi);
+}
+
+static void handle_abort(struct ucall *uc)
+{
+	TEST_FAIL("%s at %s:%ld", (const char *)uc->args[0],
+		  __FILE__, uc->args[1]);
+}
+
+static void setup_clock(struct kvm_vm *vm, struct test_case *test_case)
+{
+	struct kvm_clock_data data;
+
+	memset(&data, 0, sizeof(data));
+
+	data.clock = test_case->kvmclock_base;
+	if (test_case->realtime_offset) {
+		struct timespec ts;
+		int r;
+
+		data.flags |= KVM_CLOCK_REALTIME;
+		do {
+			r = clock_gettime(CLOCK_REALTIME, &ts);
+			if (!r)
+				break;
+		} while (errno == EINTR);
+
+		TEST_ASSERT(!r, "clock_gettime() failed: %d\n", r);
+
+		data.realtime = ts.tv_sec * NSEC_PER_SEC;
+		data.realtime += ts.tv_nsec;
+		data.realtime += test_case->realtime_offset;
+	}
+
+	vm_ioctl(vm, KVM_SET_CLOCK, &data);
+}
+
+static void enter_guest(struct kvm_vm *vm)
+{
+	struct kvm_clock_data start, end;
+	struct kvm_run *run;
+	struct ucall uc;
+	int i, r;
+
+	run = vcpu_state(vm, VCPU_ID);
+
+	for (i = 0; i < ARRAY_SIZE(test_cases); i++) {
+		setup_clock(vm, &test_cases[i]);
+
+		vm_ioctl(vm, KVM_GET_CLOCK, &start);
+
+		r = _vcpu_run(vm, VCPU_ID);
+		vm_ioctl(vm, KVM_GET_CLOCK, &end);
+
+		TEST_ASSERT(!r, "vcpu_run failed: %d\n", r);
+		TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
+			    "unexpected exit reason: %u (%s)",
+			    run->exit_reason, exit_reason_str(run->exit_reason));
+
+		switch (get_ucall(vm, VCPU_ID, &uc)) {
+		case UCALL_SYNC:
+			handle_sync(&uc, &start, &end);
+			break;
+		case UCALL_ABORT:
+			handle_abort(&uc);
+			return;
+		default:
+			TEST_ASSERT(0, "unhandled ucall: %ld\n",
+				    get_ucall(vm, VCPU_ID, &uc));
+		}
+	}
+}
+
+#define CLOCKSOURCE_PATH "/sys/devices/system/clocksource/clocksource0/current_clocksource"
+
+static void check_clocksource(void)
+{
+	char *clk_name;
+	struct stat st;
+	FILE *fp;
+
+	fp = fopen(CLOCKSOURCE_PATH, "r");
+	if (!fp) {
+		pr_info("failed to open clocksource file: %d; assuming TSC.\n",
+			errno);
+		return;
+	}
+
+	if (fstat(fileno(fp), &st)) {
+		pr_info("failed to stat clocksource file: %d; assuming TSC.\n",
+			errno);
+		goto out;
+	}
+
+	clk_name = malloc(st.st_size);
+	TEST_ASSERT(clk_name, "failed to allocate buffer to read file\n");
+
+	if (!fgets(clk_name, st.st_size, fp)) {
+		pr_info("failed to read clocksource file: %d; assuming TSC.\n",
+			ferror(fp));
+		goto out;
+	}
+
+	TEST_ASSERT(!strncmp(clk_name, "tsc\n", st.st_size),
+		    "clocksource not supported: %s", clk_name);
+out:
+	fclose(fp);
+}
+
+int main(void)
+{
+	vm_vaddr_t pvti_gva;
+	vm_paddr_t pvti_gpa;
+	struct kvm_vm *vm;
+	int flags;
+
+	flags = kvm_check_cap(KVM_CAP_ADJUST_CLOCK);
+	if (!(flags & KVM_CLOCK_REALTIME)) {
+		print_skip("KVM_CLOCK_REALTIME not supported; flags: %x",
+			   flags);
+		exit(KSFT_SKIP);
+	}
+
+	check_clocksource();
+
+	vm = vm_create_default(VCPU_ID, 0, guest_main);
+
+	pvti_gva = vm_vaddr_alloc(vm, getpagesize(), 0x10000);
+	pvti_gpa = addr_gva2gpa(vm, pvti_gva);
+	vcpu_args_set(vm, VCPU_ID, 2, pvti_gpa, pvti_gva);
+
+	enter_guest(vm);
+	kvm_vm_free(vm);
+}
