diff --git a/libraries/libmesosphere/include/mesosphere/kern_k_affinity_mask.hpp b/libraries/libmesosphere/include/mesosphere/kern_k_affinity_mask.hpp
new file mode 100644
index 000000000..a3a263fba
--- /dev/null
+++ b/libraries/libmesosphere/include/mesosphere/kern_k_affinity_mask.hpp
@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2018-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+#include <mesosphere/kern_common.hpp>
+#include <mesosphere/kern_select_cpu.hpp>
+
+namespace ams::kern {
+
+    class KAffinityMask {
+        private:
+            static constexpr u64 AllowedAffinityMask = (1ul << cpu::NumCores) - 1;
+        private:
+            u64 mask;
+        private:
+            static constexpr ALWAYS_INLINE u64 GetCoreBit(s32 core) {
+                MESOSPHERE_ASSERT(0 <= core && core < static_cast<s32>(cpu::NumCores));
+                return (1ul << core);
+            }
+        public:
+            constexpr ALWAYS_INLINE KAffinityMask() : mask(0) { MESOSPHERE_ASSERT_THIS(); }
+
+            constexpr ALWAYS_INLINE u64 GetAffinityMask() const { return this->mask; }
+
+            constexpr ALWAYS_INLINE void SetAffinityMask(u64 new_mask) {
+                MESOSPHERE_ASSERT((new_mask & ~AllowedAffinityMask) == 0);
+                this->mask = new_mask;
+            }
+
+            constexpr ALWAYS_INLINE bool GetAffinity(s32 core) const {
+                return this->mask & GetCoreBit(core);
+            }
+
+            constexpr ALWAYS_INLINE void SetAffinity(s32 core, bool set) {
+                MESOSPHERE_ASSERT(0 <= core && core < static_cast<s32>(cpu::NumCores));
+
+                if (set) {
+                    this->mask |= GetCoreBit(core);
+                } else {
+                    this->mask &= ~GetCoreBit(core);
+                }
+            }
+
+            constexpr ALWAYS_INLINE void SetAll() {
+                this->mask = AllowedAffinityMask;
+            }
+    };
+
+}
diff --git a/libraries/libmesosphere/include/mesosphere/kern_k_thread.hpp b/libraries/libmesosphere/include/mesosphere/kern_k_thread.hpp
index a34f4e800..64d8c1888 100644
--- a/libraries/libmesosphere/include/mesosphere/kern_k_thread.hpp
+++ b/libraries/libmesosphere/include/mesosphere/kern_k_thread.hpp
@@ -16,6 +16,7 @@
 #pragma once
 #include <mesosphere/kern_slab_helpers.hpp>
 #include <mesosphere/kern_k_synchronization_object.hpp>
+#include <mesosphere/kern_k_affinity_mask.hpp>
 
 namespace ams::kern {