From 367604b2f49f1b7517756a4ecab426f5308ba7fb Mon Sep 17 00:00:00 2001 From: "Liu, Zhiguang" Date: Thu, 25 Aug 2022 10:55:04 +0800 Subject: [PATCH] UefiCpuPkg/MpInitLib: Fix potential issue when IDT table is at above 4G Currently, when waking up AP, IDT table of AP will be set in 16 bit code, and assume the IDT table base is 32 bit. However, the IDT table is created by BSP. Issue will happen if the BSP allocates memory above 4G for BSP's IDT table. Moreover, even the IDT table location is below 4G, the handler function inside the IDT table is 64 bit, and it won't take effect until CPU transfers to 64 bit long mode. There is no benefit to set IDT table in such an early phase. To avoid such issue, this patch moves the LIDT instruction into 64 bit code. Cc: Eric Dong Reviewed-by: Ray Ni Cc: Rahul Kumar Signed-off-by: Zhiguang Liu --- UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm b/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm index 1daaa72b1e..cd95b03da8 100644 --- a/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm +++ b/UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm @@ -64,9 +64,6 @@ BITS 16 mov si, MP_CPU_EXCHANGE_INFO_FIELD (GdtrProfile) o32 lgdt [cs:si] - mov si, MP_CPU_EXCHANGE_INFO_FIELD (IdtrProfile) -o32 lidt [cs:si] - ; ; Switch to protected mode ; @@ -154,6 +151,11 @@ BITS 64 LongModeStart: mov esi, ebx + + ; Set IDT table at the start of 64 bit code + lea edi, [esi + MP_CPU_EXCHANGE_INFO_FIELD (IdtrProfile)] + lidt [edi] + lea edi, [esi + MP_CPU_EXCHANGE_INFO_FIELD (InitFlag)] cmp qword [edi], 1 ; ApInitConfig jnz GetApicId