diff --git a/tools/testing/selftests/kvm/include/x86_64/kvm_util_arch.h b/tools/testing/selftests/kvm/include/x86_64/kvm_util_arch.h
index 41aba476640a..d0b587c38e07 100644
--- a/tools/testing/selftests/kvm/include/x86_64/kvm_util_arch.h
+++ b/tools/testing/selftests/kvm/include/x86_64/kvm_util_arch.h
@@ -5,6 +5,8 @@
 #include <stdbool.h>
 #include <stdint.h>
 
+#include "test_util.h"
+
 extern bool is_forced_emulation_enabled;
 
 struct kvm_vm_arch {
@@ -22,4 +24,23 @@ static inline bool __vm_arch_has_protected_memory(struct kvm_vm_arch *arch)
 #define vm_arch_has_protected_memory(vm) \
 	__vm_arch_has_protected_memory(&(vm)->arch)
 
+#define vcpu_arch_put_guest(mem, __val)							\
+do {											\
+	const typeof(mem) val = (__val);						\
+											\
+	if (!is_forced_emulation_enabled || guest_random_bool(&guest_rng)) {		\
+		(mem) = val;								\
+	} else if (guest_random_bool(&guest_rng)) {					\
+		__asm__ __volatile__(KVM_FEP "mov %1, %0"				\
+				     : "+m" (mem)					\
+				     : "r" (val) : "memory");				\
+	} else {									\
+		uint64_t __old = READ_ONCE(mem);					\
+											\
+		__asm__ __volatile__(KVM_FEP LOCK_PREFIX "cmpxchg %[new], %[ptr]"	\
+				     : [ptr] "+m" (mem), [old] "+a" (__old)		\
+				     : [new]"r" (val) : "memory", "cc");		\
+	}										\
+} while (0)
+
 #endif  // SELFTEST_KVM_UTIL_ARCH_H