UefiCpuPkg: Solve that stack top address is not mapped in pagetable

For the case CPU logic index is 0, RSP points to the very top of all AP
stacks. That address is not mapped in page table.

Cc: Guo Dong <guo.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Sean Rhodes <sean@starlabs.systems>
Cc: James Lu <james.lu@intel.com>
Cc: Gua Guo <gua.guo@intel.com>
Signed-off-by: Ted Kuo <ted.kuo@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>

diff --git a/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm b/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm
index 9ebe31795b00c85dbe2b119eb381b6c90e15433b..5bcdf7726ba6080bdb91f4b3dafb6bb485792bbe 100644 (file)
--- a/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm
+++ b/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm
@@ -315,6 +315,7 @@ MwaitCheckGeneric:
 MwaitLoopGeneric:\r
     cli\r
     mov        rax, rsp           ; Set Monitor Address\r
+    sub        eax, 8             ; To ensure the monitor address is in the page table\r
     xor        ecx, ecx           ; ecx = 0\r
     xor        edx, edx           ; edx = 0\r
     monitor\r