diff --git a/Kernel/Arch/i386/CPU.h b/Kernel/Arch/i386/CPU.h
index 84ed4b05e5..54a61eb8dc 100644
--- a/Kernel/Arch/i386/CPU.h
+++ b/Kernel/Arch/i386/CPU.h
@@ -672,7 +672,7 @@ class Processor {
     Atomic<u32, AK::MemoryOrder::memory_order_relaxed> m_in_critical;
     static Atomic<u32> s_idle_cpu_mask;
 
-    TSS32 m_tss;
+    TSS m_tss;
     static FPUState s_clean_fpu_state;
     CPUFeature m_features;
     static volatile u32 g_total_processors; // atomic
@@ -1140,5 +1140,4 @@ ALWAYS_INLINE void clac()
     asm volatile("clac" ::
                      : "cc");
 }
-
 }
diff --git a/Kernel/Arch/x86_64/CPU.h b/Kernel/Arch/x86_64/CPU.h
new file mode 100644
index 0000000000..e307ab606f
--- /dev/null
+++ b/Kernel/Arch/x86_64/CPU.h
@@ -0,0 +1,114 @@
+/*
+ * Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, Leon Albrecht <leon2002.la@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/Types.h>
+#include <Kernel/VirtualAddress.h>
+
+namespace Kernel {
+
+struct [[gnu::packed]] TSS64
+{
+    u32 __1; // Link?
+    u64 rsp0;
+    u64 rsp1;
+    u64 rsp2;
+    u64 __2; // IST0 -> empty?
+    u64 ist1;
+    u64 ist2;
+    u64 ist3;
+    u64 ist4;
+    u64 ist5;
+    u64 ist6;
+    u64 ist7;
+    u64 __3;
+    u16 __4;
+    u16 iomapbase;
+};
+
+union [[gnu::packed]] Descriptor
+{
+    struct {
+        u16 limit_lo;
+        u16 base_lo;
+        u8 base_hi;
+        u8 type : 4;
+        u8 descriptor_type : 1;
+        u8 dpl : 2;
+        u8 segment_present : 1;
+        u8 limit_hi : 4;
+        u8 : 1;
+        u8 operation_size64 : 1;
+        u8 operation_size32 : 1;
+        u8 granularity : 1;
+        u8 base_hi2;
+    };
+    struct {
+        u32 low;
+        u32 high;
+    };
+
+    enum Type {
+        Invalid = 0,
+        AvailableTSS_16bit = 0x1,
+        LDT = 0x2,
+        BusyTSS_16bit = 0x3,
+        CallGate_16bit = 0x4,
+        TaskGate = 0x5,
+        InterruptGate_16bit = 0x6,
+        TrapGate_16bit = 0x7,
+        AvailableTSS_32bit = 0x9,
+        BusyTSS_32bit = 0xb,
+        CallGate_32bit = 0xc,
+        InterruptGate_32bit = 0xe,
+        TrapGate_32bit = 0xf,
+    };
+
+    VirtualAddress base() const
+    {
+        FlatPtr base = base_lo;
+        base |= base_hi << 16u;
+        base |= base_hi2 << 24u;
+        return VirtualAddress { base };
+    }
+
+    void set_base(VirtualAddress base)
+    {
+        base_lo = base.get() & 0xffffu;
+        base_hi = (base.get() >> 16u) & 0xffu;
+        base_hi2 = (base.get() >> 24u) & 0xffu;
+    }
+
+    void set_limit(u32 length)
+    {
+        limit_lo = length & 0xffff;
+        limit_hi = (length >> 16) & 0xf;
+    }
+};
+
+}