[NTOS:KE] Also rewrite KeZeroPages in assembly for amd64

Let's stick with "rep movsq" until we are able to have more precise benchmarks

ntoskrnl/ke/amd64/stubs.c

@@ -88,16 +88,6 @@ KiDpcInterruptHandler(VOID)
     KeLowerIrql(OldIrql);
 }
 
-
-VOID
-FASTCALL
-KeZeroPages(IN PVOID Address,
-            IN ULONG Size)
-{
-    /* Not using XMMI in this routine */
-    RtlZeroMemory(Address, Size);
-}
-
 PVOID
 KiSwitchKernelStackHelper(
     LONG_PTR StackOffset,

ntoskrnl/ke/amd64/zeropage.S

@@ -0,0 +1,45 @@
+/*
+ * PROJECT:     ReactOS Kernel
+ * LICENSE:     GPL-2.0-or-later (https://spdx.org/licenses/GPL-2.0-or-later)
+ * PURPOSE:     Fast zeroing of pages
+ * COPYRIGHT:   Copyright 2021 Jérôme Gardou <jerome.gardou@reactos.org>
+ */
+
+#include <asm.inc>
+
+/* FUNCTIONS ****************************************************************/
+.code
+
+/* Benchmarking from Timo on some AMD machine:
+    rep movsq : 128
+    movaps 175
+    movnti 620
+    movntdq: 620
+    movntps: 620
+    MS KeZeroPages (movnti unrolled): 883
+    MS KeZeroSinglePage (mov): 346
+
+    whole discussion in https://github.com/reactos/reactos/pull/3765
+    We stick with rep stosq.
+*/
+
+/*
+ * VOID
+ * KeZeroPages(PVOID Ptr, ULONG Size);
+ */
+PUBLIC KeZeroPages
+FUNC KeZeroPages
+    push rdi
+    .PUSHREG rdi
+    .ENDPROLOG
+
+    mov rdi, rcx
+    mov ecx, edx
+    shr ecx, 3
+    xor rax, rax
+    rep stosq
+    pop rdi
+    ret
+ENDFUNC
+
+END

ntoskrnl/ntos.cmake

@@ -328,7 +328,8 @@ elseif(ARCH STREQUAL "amd64")
         ${REACTOS_SOURCE_DIR}/ntoskrnl/ke/amd64/boot.S
         ${REACTOS_SOURCE_DIR}/ntoskrnl/ke/amd64/ctxswitch.S
         ${REACTOS_SOURCE_DIR}/ntoskrnl/ke/amd64/trap.S
-        ${REACTOS_SOURCE_DIR}/ntoskrnl/ke/amd64/usercall_asm.S)
+        ${REACTOS_SOURCE_DIR}/ntoskrnl/ke/amd64/usercall_asm.S
+        ${REACTOS_SOURCE_DIR}/ntoskrnl/ke/amd64/zeropage.S)
     list(APPEND SOURCE
         ${REACTOS_SOURCE_DIR}/ntoskrnl/config/i386/cmhardwr.c
         ${REACTOS_SOURCE_DIR}/ntoskrnl/mm/i386/page.c