Re: [PATCH v3] IntelFsp2Pkg: FSP_TEMP_RAM_INIT call must follow X64 Calling Convention


HI Chasel,
Yes, we don't need to modify esp for LoadMicrocodeDefault. However, this function does couple of MSR Accesses in b/w that would lead to modify RCX anyway.
So, if not RSP, we need to use different register to save RCX and consume in the whole function.

That's why I have not changed the usage of RSP to hold the input parameter.


-----Original Message-----
From: Chiu, Chasel <chasel.chiu@...>
Sent: Monday, May 16, 2022 5:38 PM
To: Duggapu, Chinni B <chinni.b.duggapu@...>;
Cc: Desimone, Nathaniel L <nathaniel.l.desimone@...>; Zeng, Star <star.zeng@...>; S, Ashraf Ali <ashraf.ali.s@...>
Subject: RE: [PATCH v3] IntelFsp2Pkg: FSP_TEMP_RAM_INIT call must follow X64 Calling Convention

Thanks for correcting format and updating patch per feedbacks!
Just one more comment below inline and please also help to include patch of IntelFsp2WrapperPkg\Library\SecFspWrapperPlatformSecLibSample\X64\SecEntry.nasm for passing API parameter by RCX.
You might want to create a patch series:
[1/2] IntelFsp2Pkg patch
[2/2] IntelFsp2WrapperPkg patch


-----Original Message-----
From: Duggapu, Chinni B <chinni.b.duggapu@...>
Sent: Monday, May 16, 2022 6:54 PM
Cc: Chiu, Chasel <chasel.chiu@...>; Desimone, Nathaniel L
<nathaniel.l.desimone@...>; Zeng, Star <star.zeng@...>; S,
Ashraf Ali <ashraf.ali.s@...>
Subject: [PATCH v3] IntelFsp2Pkg: FSP_TEMP_RAM_INIT call must follow
X64 Calling Convention

This API accept one parameter using RCX and this is consumed in
mutiple sub functions.

Cc: Chasel Chiu <chasel.chiu@...>
Cc: Nate DeSimone <nathaniel.l.desimone@...>
Cc: Star Zeng <star.zeng@...>
Cc: Ashraf Ali S <ashraf.ali.s@...>
Signed-off-by: cbduggap <chinni.b.duggapu@...>
IntelFsp2Pkg/FspSecCore/X64/FspApiEntryT.nasm | 26 ++++++++---------
.../Include/ | 28 +++++++++++++++++++
2 files changed, 41 insertions(+), 13 deletions(-)

diff --git a/IntelFsp2Pkg/FspSecCore/X64/FspApiEntryT.nasm
index a9f5f28ed7..9504c96b81 100644
--- a/IntelFsp2Pkg/FspSecCore/X64/FspApiEntryT.nasm
+++ b/IntelFsp2Pkg/FspSecCore/X64/FspApiEntryT.nasm
@@ -114,7 +114,7 @@ endstruc
global ASM_PFX(LoadMicrocodeDefault)
ASM_PFX(LoadMicrocodeDefault): ; Inputs:- ; rsp ->
LoadMicrocodeParams pointer+ ; rcx -> LoadMicrocodeParams pointer ;
Register Usage: ; rsp Preserved ; All others destroyed@@ -130,10
+130,9 @@ ASM_PFX(LoadMicrocodeDefault):
cmp rsp, 0 jz ParamError- mov eax, dword [rsp + 8] ;
Parameter pointer- cmp eax, 0+ cmp ecx, 0 jz ParamError- mov
esp, eax+ mov esp, ecx

I think we do not need to modify esp because now esp/rsp only containing return address initialized by caller.

; skip loading Microcode if the
MicrocodeCodeSize is zero ; and report error if size is less than 2k@@ -
321,8 +320,7 @@ ASM_PFX(EstablishStackFsp):
; ; Save parameter pointer in rdx ;- mov rdx, qword [rsp + 8]-+ mov
rdx, rcx ; ; Enable FSP STACK ;@@ -420,7 +418,10 @@
; ENABLE_SSE ENABLE_AVX-+ ;+ ; Save Input Parameter in YMM10+ ;+
SAVE_RCX ; ; Save RBP, RBX, RSI, RDI and RSP in YMM7, YMM8 and
YMM6 ;@@ -442,9 +443,8 @@ ASM_PFX(TempRamInitApi):
; ; Check Parameter ;- mov rax, qword [rsp + 8]- cmp rax, 0-
mov rax, 08000000000000002h+ cmp rcx, 0+ mov rcx,
08000000000000002h jz TempRamInitExit ;@@ -455,18 +455,18
@@ ASM_PFX(TempRamInitApi):
jnz TempRamInitExit ; Load microcode- LOAD_RSP+ LOAD_RCX
rax ; Save microcode return status in SLOT 0 in YMM9 (upper
128bits). ; @note If return value rax is not 0, microcode did not load, but
continue and attempt to boot. ; Call Sec CAR Init- LOAD_RSP+ LOAD_RCX
CALL_YMM ASM_PFX(SecCarInit) cmp rax, 0 jnz TempRamInitExit
- LOAD_RSP+ LOAD_RCX CALL_YMM ASM_PFX(EstablishStackFsp) cmp
rax, 0 jnz TempRamInitExitdiff --git
index e8bd91669d..38c807a311 100644
--- a/IntelFsp2Pkg/Include/
+++ b/IntelFsp2Pkg/Include/
@@ -177,6 +177,30 @@
LXMMN xmm5, %1, 1 %endmacro +;+; Upper half of
YMM10 to save/restore RCX+;+;+; Save RCX to YMM10[128:191]+;
Modified: XMM5 and YMM10+;++%macro SAVE_RCX 0+ LYMMN
ymm10, xmm5, 1+ SXMMN xmm5, 0, rcx+ SYMMN ymm10,
1, xmm5+ %endmacro++;+; Restore RCX from YMM10[128:191]+;
Modified: XMM5 and RCX+;++%macro LOAD_RCX 0+ LYMMN
ymm10, xmm5, 1+ movq rcx, xmm5+ %endmacro+ ; ;
YMM7[128:191] for calling stack ; arg 1:Entry@@ -231,6 +255,7 @@
; Use CpuId instruction (CPUID.01H:EDX.SSE[bit 25] = 1) to
test ; whether the processor supports SSE instruction. ;+
mov r10, rcx mov rax, 1 cpuid bt rdx, 25@@ -
241,6 +266,7 @@ NextAddress:
; bt ecx, 19 jnc SseError+ mov rcx,
r10 ; ; Set OSFXSR bit (bit #9) & OSXMMEXCPT bit (bit
#10)@@ -258,6 +284,7 @@ NextAddress:
%endmacro %macro ENABLE_AVX 0+ mov r10, rcx
mov eax, 1 cpuid and ecx, 10000000h@@ -280,5 +307,6
@@ EnableAvx:
xgetbv ; result in edx:eax or eax, 00000006h ; Set
XCR0 bit #1 and bit #2 to enable SSE state and AVX state xsetbv+
mov rcx, r10 %endmacro --

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