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* [PATCH v6] MdePkg: BaseIoLibIntrinsic (IoLib class) library
@ 2017-04-06 14:22 Leo Duran
  2017-04-06 14:22 ` Leo Duran
  0 siblings, 1 reply; 2+ messages in thread
From: Leo Duran @ 2017-04-06 14:22 UTC (permalink / raw)
  To: edk2-devel; +Cc: Leo Duran

This patch adds an SEV-specific .INF and corresponding assembly
files, to unroll REP INSx/OUTSx on IoRead/WriteFifo#() routines
when the SEV feature is enabled under a hypervisor environment.
    
The new .INF only supports the IA32 and X64 architectures.

This patch follows the series "[PATCH v3 00/10] IoLib class library",
which has already being pushed upstream.

Changes since v5:
- Include missing .INF file

Leo Duran (1):
  MdePkg: BaseIoLibIntrinsic (IoLib class) library

 .../BaseIoLibIntrinsic/BaseIoLibIntrinsicSev.inf   |  59 +++++
 .../Library/BaseIoLibIntrinsic/Ia32/IoFifoSev.nasm | 293 +++++++++++++++++++++
 .../Library/BaseIoLibIntrinsic/X64/IoFifoSev.nasm  | 282 ++++++++++++++++++++
 3 files changed, 634 insertions(+)
 create mode 100644 MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicSev.inf
 create mode 100644 MdePkg/Library/BaseIoLibIntrinsic/Ia32/IoFifoSev.nasm
 create mode 100644 MdePkg/Library/BaseIoLibIntrinsic/X64/IoFifoSev.nasm

-- 
2.7.4



^ permalink raw reply	[flat|nested] 2+ messages in thread

* [PATCH v6] MdePkg: BaseIoLibIntrinsic (IoLib class) library
  2017-04-06 14:22 [PATCH v6] MdePkg: BaseIoLibIntrinsic (IoLib class) library Leo Duran
@ 2017-04-06 14:22 ` Leo Duran
  0 siblings, 0 replies; 2+ messages in thread
From: Leo Duran @ 2017-04-06 14:22 UTC (permalink / raw)
  To: edk2-devel; +Cc: Leo Duran, Michael D Kinney, Liming Gao, Brijesh Singh

This patch adds an SEV-specific .INF and corresponding assembly
files, to unroll REP INSx/OUTSx on IoRead/WriteFifo#() routines
when the SEV feature is enabled under a hypervisor environment.

The new .INF only supports the IA32 and X64 architectures.

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Leo Duran <leo.duran@amd.com>
---
 .../BaseIoLibIntrinsic/BaseIoLibIntrinsicSev.inf   |  59 +++++
 .../Library/BaseIoLibIntrinsic/Ia32/IoFifoSev.nasm | 293 +++++++++++++++++++++
 .../Library/BaseIoLibIntrinsic/X64/IoFifoSev.nasm  | 282 ++++++++++++++++++++
 3 files changed, 634 insertions(+)
 create mode 100644 MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicSev.inf
 create mode 100644 MdePkg/Library/BaseIoLibIntrinsic/Ia32/IoFifoSev.nasm
 create mode 100644 MdePkg/Library/BaseIoLibIntrinsic/X64/IoFifoSev.nasm

diff --git a/MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicSev.inf b/MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicSev.inf
new file mode 100644
index 0000000..0eec896
--- /dev/null
+++ b/MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicSev.inf
@@ -0,0 +1,59 @@
+## @file
+#  Instance of I/O Library using compiler intrinsics.
+#
+#  I/O Library that uses compiler intrinsics to perform IN and OUT instructions
+#  for IA-32 and x64.
+#
+#  Copyright (c) 2007 - 2015, Intel Corporation. All rights reserved.<BR>
+#  Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
+#  Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
+#
+#  This program and the accompanying materials
+#  are licensed and made available under the terms and conditions of the BSD License
+#  which accompanies this distribution. The full text of the license may be found at
+#  http://opensource.org/licenses/bsd-license.php.
+#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+#
+##
+
+[Defines]
+  INF_VERSION                    = 0x00010005
+  BASE_NAME                      = BaseIoLibIntrinsicSev
+  MODULE_UNI_FILE                = BaseIoLibIntrinsic.uni
+  FILE_GUID                      = 93742f95-6e71-4581-b600-8e1da443f95a
+  MODULE_TYPE                    = BASE
+  VERSION_STRING                 = 1.0
+  LIBRARY_CLASS                  = IoLib 
+
+
+#
+#  VALID_ARCHITECTURES           = IA32 X64
+#
+
+[Sources]
+  IoLibMmioBuffer.c
+  BaseIoLibIntrinsicInternal.h
+  IoHighLevel.c
+
+[Sources.IA32]
+  IoLibGcc.c    | GCC
+  IoLibMsc.c    | MSFT
+  IoLibIcc.c    | INTEL
+  IoLib.c
+  Ia32/IoFifoSev.nasm
+
+[Sources.X64]
+  IoLibGcc.c    | GCC
+  IoLibMsc.c    | MSFT
+  IoLibIcc.c    | INTEL
+  IoLib.c
+  X64/IoFifoSev.nasm
+
+[Packages]
+  MdePkg/MdePkg.dec
+
+[LibraryClasses]
+  DebugLib
+  BaseLib
+
diff --git a/MdePkg/Library/BaseIoLibIntrinsic/Ia32/IoFifoSev.nasm b/MdePkg/Library/BaseIoLibIntrinsic/Ia32/IoFifoSev.nasm
new file mode 100644
index 0000000..9adb972
--- /dev/null
+++ b/MdePkg/Library/BaseIoLibIntrinsic/Ia32/IoFifoSev.nasm
@@ -0,0 +1,293 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (c) 2006 - 2012, Intel Corporation. All rights reserved.<BR>
+; Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
+;
+; This program and the accompanying materials are licensed and made available
+; under the terms and conditions of the BSD License which accompanies this
+; distribution.  The full text of the license may be found at
+; http://opensource.org/licenses/bsd-license.php.
+;
+; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+;
+;------------------------------------------------------------------------------
+
+    SECTION .text
+
+;------------------------------------------------------------------------------
+; Check whether we need to unroll the String I/O under SEV guest
+;
+; Return // eax   (1 - unroll, 0 - no unroll)
+;------------------------------------------------------------------------------
+global ASM_PFX(SevNoRepIo)
+ASM_PFX(SevNoRepIo):
+
+  ; CPUID clobbers ebx, ecx and edx
+  push      ebx
+  push      ecx
+  push      edx
+
+  ; Check if we are running under hypervisor
+  ; CPUID(1).ECX Bit 31
+  mov       eax, 1
+  cpuid
+  bt        ecx, 31
+  jnc       @UseRepIo
+
+  ; Check if we have Memory encryption CPUID leaf
+  mov       eax, 0x80000000
+  cpuid
+  cmp       eax, 0x8000001f
+  jl        @UseRepIo
+
+  ; Check for memory encryption feature:
+  ;  CPUID  Fn8000_001F[EAX] - Bit 1
+  ;
+  mov       eax,  0x8000001f
+  cpuid
+  bt        eax, 1
+  jnc       @UseRepIo
+
+  ; Check if memory encryption is enabled
+  ;  MSR_0xC0010131 - Bit 0 (SEV enabled)
+  ;  MSR_0xC0010131 - Bit 1 (SEV-ES enabled)
+  mov       ecx, 0xc0010131
+  rdmsr
+
+  ; Check for (SevEsEnabled == 0 && SevEnabled == 1)
+  and       eax, 3
+  cmp       eax, 1
+  je        @SevNoRepIo_Done
+
+@UseRepIo:
+  xor       eax, eax
+
+@SevNoRepIo_Done:
+  pop       edx
+  pop       ecx
+  pop       ebx
+  ret
+
+;------------------------------------------------------------------------------
+;  VOID
+;  EFIAPI
+;  IoReadFifo8 (
+;    IN  UINTN                 Port,
+;    IN  UINTN                 Size,
+;    OUT VOID                  *Buffer
+;    );
+;------------------------------------------------------------------------------
+global ASM_PFX(IoReadFifo8)
+ASM_PFX(IoReadFifo8):
+    push    edi
+    mov     dx, [esp + 8]
+    mov     ecx, [esp + 12]
+    mov     edi, [esp + 16]
+
+    call    SevNoRepIo            ; Check if we need to unroll the rep
+    test    eax, eax
+    jnz     @IoReadFifo8_NoRep
+
+    cld
+    rep     insb
+    jmp     @IoReadFifo8_Done
+
+@IoReadFifo8_NoRep:
+    jecxz   @IoReadFifo8_Done
+
+@IoReadFifo8_Loop:
+    in      al, dx
+    mov     byte [edi], al
+    inc     edi
+    loop    @IoReadFifo8_Loop
+
+@IoReadFifo8_Done:
+    pop     edi
+    ret
+
+;------------------------------------------------------------------------------
+;  VOID
+;  EFIAPI
+;  IoReadFifo16 (
+;    IN  UINTN                 Port,
+;    IN  UINTN                 Size,
+;    OUT VOID                  *Buffer
+;    );
+;------------------------------------------------------------------------------
+global ASM_PFX(IoReadFifo16)
+ASM_PFX(IoReadFifo16):
+    push    edi
+    mov     dx, [esp + 8]
+    mov     ecx, [esp + 12]
+    mov     edi, [esp + 16]
+
+    call    SevNoRepIo            ; Check if we need to unroll the rep
+    test    eax, eax
+    jnz     @IoReadFifo16_NoRep
+
+    cld
+    rep     insw
+    jmp     @IoReadFifo16_Done
+
+@IoReadFifo16_NoRep:
+    jecxz   @IoReadFifo16_Done
+
+@IoReadFifo16_Loop:
+    in      ax, dx
+    mov     word [edi], ax
+    add     edi, 2
+    loop    @IoReadFifo16_Loop
+
+@IoReadFifo16_Done:
+    pop     edi
+    ret
+
+;------------------------------------------------------------------------------
+;  VOID
+;  EFIAPI
+;  IoReadFifo32 (
+;    IN  UINTN                 Port,
+;    IN  UINTN                 Size,
+;    OUT VOID                  *Buffer
+;    );
+;------------------------------------------------------------------------------
+global ASM_PFX(IoReadFifo32)
+ASM_PFX(IoReadFifo32):
+    push    edi
+    mov     dx, [esp + 8]
+    mov     ecx, [esp + 12]
+    mov     edi, [esp + 16]
+
+    call    SevNoRepIo            ; Check if we need to unroll the rep
+    test    eax, eax
+    jnz     @IoReadFifo32_NoRep
+
+    cld
+    rep     insd
+    jmp     @IoReadFifo32_Done
+
+@IoReadFifo32_NoRep:
+    jecxz   @IoReadFifo32_Done
+
+@IoReadFifo32_Loop:
+    in      eax, dx
+    mov     dword [edi], eax
+    add     edi, 4
+    loop    @IoReadFifo32_Loop
+
+@IoReadFifo32_Done:
+    pop     edi
+    ret
+
+;------------------------------------------------------------------------------
+;  VOID
+;  EFIAPI
+;  IoWriteFifo8 (
+;    IN UINTN                  Port,
+;    IN UINTN                  Size,
+;    IN VOID                   *Buffer
+;    );
+;------------------------------------------------------------------------------
+global ASM_PFX(IoWriteFifo8)
+ASM_PFX(IoWriteFifo8):
+    push    esi
+    mov     dx, [esp + 8]
+    mov     ecx, [esp + 12]
+    mov     esi, [esp + 16]
+
+    call    SevNoRepIo     	; Check if we need to unroll String I/O
+    test    eax, eax
+    jnz     @IoWriteFifo8_NoRep
+
+    cld
+    rep     outsb
+    jmp     @IoWriteFifo8_Done
+
+@IoWriteFifo8_NoRep:
+    jecxz   @IoWriteFifo8_Done
+
+@IoWriteFifo8_Loop:
+    mov     byte [esi], al
+    out     dx, al
+    inc     esi
+    loop    @IoWriteFifo8_Loop
+
+@IoWriteFifo8_Done:
+    pop     esi
+    ret
+
+;------------------------------------------------------------------------------
+;  VOID
+;  EFIAPI
+;  IoWriteFifo16 (
+;    IN UINTN                  Port,
+;    IN UINTN                  Size,
+;    IN VOID                   *Buffer
+;    );
+;------------------------------------------------------------------------------
+global ASM_PFX(IoWriteFifo16)
+ASM_PFX(IoWriteFifo16):
+    push    esi
+    mov     dx, [esp + 8]
+    mov     ecx, [esp + 12]
+    mov     esi, [esp + 16]
+
+    call    SevNoRepIo     	; Check if we need to unroll String I/O
+    test    eax, eax
+    jnz     @IoWriteFifo16_NoRep
+
+    cld
+    rep     outsw
+    jmp     @IoWriteFifo16_Done
+
+@IoWriteFifo16_NoRep:
+    jecxz   @IoWriteFifo16_Done
+
+@IoWriteFifo16_Loop:
+    mov     word [esi], ax
+    out     dx, ax
+    add     esi, 2
+    loop    @IoWriteFifo16_Loop
+
+@IoWriteFifo16_Done:
+    pop     esi
+    ret
+
+;------------------------------------------------------------------------------
+;  VOID
+;  EFIAPI
+;  IoWriteFifo32 (
+;    IN UINTN                  Port,
+;    IN UINTN                  Size,
+;    IN VOID                   *Buffer
+;    );
+;------------------------------------------------------------------------------
+global ASM_PFX(IoWriteFifo32)
+ASM_PFX(IoWriteFifo32):
+    push    esi
+    mov     dx, [esp + 8]
+    mov     ecx, [esp + 12]
+    mov     esi, [esp + 16]
+
+    call    SevNoRepIo     	; Check if we need to unroll String I/O
+    test    eax, eax
+    jnz     @IoWriteFifo32_NoRep
+
+    cld
+    rep     outsd
+    jmp     @IoWriteFifo32_Done
+
+@IoWriteFifo32_NoRep:
+    jecxz   @IoWriteFifo32_Done
+
+@IoWriteFifo32_Loop:
+    mov     dword [esi], eax
+    out     dx, eax
+    add     esi, 4
+    loop    @IoWriteFifo32_Loop
+
+@IoWriteFifo32_Done:
+    pop     esi
+    ret
+
diff --git a/MdePkg/Library/BaseIoLibIntrinsic/X64/IoFifoSev.nasm b/MdePkg/Library/BaseIoLibIntrinsic/X64/IoFifoSev.nasm
new file mode 100644
index 0000000..20e3e64
--- /dev/null
+++ b/MdePkg/Library/BaseIoLibIntrinsic/X64/IoFifoSev.nasm
@@ -0,0 +1,282 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (c) 2006 - 2012, Intel Corporation. All rights reserved.<BR>
+; Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
+;
+; This program and the accompanying materials are licensed and made available
+; under the terms and conditions of the BSD License which accompanies this
+; distribution.  The full text of the license may be found at
+; http://opensource.org/licenses/bsd-license.php.
+;
+; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+;
+;------------------------------------------------------------------------------
+
+    DEFAULT REL
+    SECTION .text
+
+;------------------------------------------------------------------------------
+; Check whether we need to unroll the String I/O in SEV guest
+;
+; Return // eax   (1 - unroll, 0 - no unroll)
+;------------------------------------------------------------------------------
+global ASM_PFX(SevNoRepIo)
+ASM_PFX(SevNoRepIo):
+
+  ; CPUID clobbers ebx, ecx and edx
+  push      rbx
+  push      rcx
+  push      rdx
+
+  ; Check if we are runing under hypervisor
+  ; CPUID(1).ECX Bit 31
+  mov       eax, 1
+  cpuid
+  bt        ecx, 31
+  jnc       @UseRepIo
+
+  ; Check if we have Memory encryption CPUID leaf
+  mov       eax, 0x80000000
+  cpuid
+  cmp       eax, 0x8000001f
+  jl        @UseRepIo
+
+  ; Check for memory encryption feature:
+  ;  CPUID  Fn8000_001F[EAX] - Bit 1
+  ;
+  mov       eax,  0x8000001f
+  cpuid
+  bt        eax, 1
+  jnc       @UseRepIo
+
+  ; Check if memory encryption is enabled
+  ;  MSR_0xC0010131 - Bit 0 (SEV enabled)
+  ;  MSR_0xC0010131 - Bit 1 (SEV-ES enabled)
+  mov       ecx, 0xc0010131
+  rdmsr
+
+  ; Check for (SevEsEnabled == 0 && SevEnabled == 1)
+  and       eax, 3
+  cmp       eax, 1
+  je        @SevNoRepIo_Done
+
+@UseRepIo:
+  xor       eax, eax
+
+@SevNoRepIo_Done:
+  pop       rdx
+  pop       rcx
+  pop       rbx
+  ret
+
+;------------------------------------------------------------------------------
+;  VOID
+;  EFIAPI
+;  IoReadFifo8 (
+;    IN  UINTN                 Port,              // rcx
+;    IN  UINTN                 Size,              // rdx
+;    OUT VOID                  *Buffer            // r8
+;    );
+;------------------------------------------------------------------------------
+global ASM_PFX(IoReadFifo8)
+ASM_PFX(IoReadFifo8):
+    xchg    rcx, rdx
+    xchg    rdi, r8             ; rdi: buffer address; r8: save rdi
+
+    call    SevNoRepIo          ; Check if we need to unroll String I/O
+    test    eax, eax
+    jnz     @IoReadFifo8_NoRep
+
+    cld
+    rep     insb
+    jmp     @IoReadFifo8_Done
+
+@IoReadFifo8_NoRep:
+    jrcxz   @IoReadFifo8_Done
+
+@IoReadFifo8_Loop:
+    in      al, dx
+    mov     byte [rdi], al
+    inc     rdi
+    loop    @IoReadFifo8_Loop
+
+@IoReadFifo8_Done:
+    mov     rdi, r8             ; restore rdi
+    ret
+
+;------------------------------------------------------------------------------
+;  VOID
+;  EFIAPI
+;  IoReadFifo16 (
+;    IN  UINTN                 Port,              // rcx
+;    IN  UINTN                 Size,              // rdx
+;    OUT VOID                  *Buffer            // r8
+;    );
+;------------------------------------------------------------------------------
+global ASM_PFX(IoReadFifo16)
+ASM_PFX(IoReadFifo16):
+    xchg    rcx, rdx
+    xchg    rdi, r8             ; rdi: buffer address; r8: save rdi
+
+    call    SevNoRepIo          ; Check if we need to unroll String I/O
+    test    eax, eax
+    jnz     @IoReadFifo16_NoRep
+
+    cld
+    rep     insw
+    jmp     @IoReadFifo16_Done
+
+@IoReadFifo16_NoRep:
+    jrcxz   @IoReadFifo16_Done
+
+@IoReadFifo16_Loop:
+    in      ax, dx
+    mov     word [rdi], ax
+    add     rdi, 2
+    loop    @IoReadFifo16_Loop
+
+@IoReadFifo16_Done:
+    mov     rdi, r8             ; restore rdi
+    ret
+
+;------------------------------------------------------------------------------
+;  VOID
+;  EFIAPI
+;  IoReadFifo32 (
+;    IN  UINTN                 Port,              // rcx
+;    IN  UINTN                 Size,              // rdx
+;    OUT VOID                  *Buffer            // r8
+;    );
+;------------------------------------------------------------------------------
+global ASM_PFX(IoReadFifo32)
+ASM_PFX(IoReadFifo32):
+    xchg    rcx, rdx
+    xchg    rdi, r8             ; rdi: buffer address; r8: save rdi
+
+    call    SevNoRepIo     	; Check if we need to unroll String I/O
+    test    eax, eax
+    jnz     @IoReadFifo32_NoRep
+
+    cld
+    rep     insd
+    jmp     @IoReadFifo32_Done
+
+@IoReadFifo32_NoRep:
+    jrcxz   @IoReadFifo32_Done
+
+@IoReadFifo32_Loop:
+    in      eax, dx
+    mov     dword [rdi], eax
+    add     rdi, 4
+    loop    @IoReadFifo32_Loop
+
+@IoReadFifo32_Done:
+    mov     rdi, r8             ; restore rdi
+    ret
+
+;------------------------------------------------------------------------------
+;  VOID
+;  EFIAPI
+;  IoWriteFifo8 (
+;    IN UINTN                  Port,              // rcx
+;    IN UINTN                  Size,              // rdx
+;    IN VOID                   *Buffer            // r8
+;    );
+;------------------------------------------------------------------------------
+global ASM_PFX(IoWriteFifo8)
+ASM_PFX(IoWriteFifo8):
+    xchg    rcx, rdx
+    xchg    rsi, r8             ; rsi: buffer address; r8: save rsi
+
+    call    SevNoRepIo     	; Check if we need to unroll String I/O
+    test    eax, eax
+    jnz     @IoWriteFifo8_NoRep
+
+    cld
+    rep     outsb
+    jmp     @IoWriteFifo8_Done
+
+@IoWriteFifo8_NoRep:
+    jrcxz   @IoWriteFifo8_Done
+
+@IoWriteFifo8_Loop:
+    mov     byte [rsi], al
+    out     dx, al
+    inc     rsi
+    loop    @IoWriteFifo8_Loop
+
+@IoWriteFifo8_Done:
+    mov     rsi, r8             ; restore rsi
+    ret
+
+;------------------------------------------------------------------------------
+;  VOID
+;  EFIAPI
+;  IoWriteFifo16 (
+;    IN UINTN                  Port,              // rcx
+;    IN UINTN                  Size,              // rdx
+;    IN VOID                   *Buffer            // r8
+;    );
+;------------------------------------------------------------------------------
+global ASM_PFX(IoWriteFifo16)
+ASM_PFX(IoWriteFifo16):
+    xchg    rcx, rdx
+    xchg    rsi, r8             ; rsi: buffer address; r8: save rsi
+
+    call    SevNoRepIo     	; Check if we need to unroll String I/O
+    test    eax, eax
+    jnz     @IoWriteFifo16_NoRep
+
+    cld
+    rep     outsw
+    jmp     @IoWriteFifo16_Done
+
+@IoWriteFifo16_NoRep:
+    jrcxz   @IoWriteFifo16_Done
+
+@IoWriteFifo16_Loop:
+    mov     word [rsi], ax
+    out     dx, ax
+    add     rsi, 2
+    loop    @IoWriteFifo16_Loop
+
+@IoWriteFifo16_Done:
+    mov     rsi, r8             ; restore rsi
+    ret
+
+;------------------------------------------------------------------------------
+;  VOID
+;  EFIAPI
+;  IoWriteFifo32 (
+;    IN UINTN                  Port,              // rcx
+;    IN UINTN                  Size,              // rdx
+;    IN VOID                   *Buffer            // r8
+;    );
+;------------------------------------------------------------------------------
+global ASM_PFX(IoWriteFifo32)
+ASM_PFX(IoWriteFifo32):
+    xchg    rcx, rdx
+    xchg    rsi, r8             ; rsi: buffer address; r8: save rsi
+
+    call    SevNoRepIo     	; Check if we need to unroll String I/O
+    test    eax, eax
+    jnz     @IoWriteFifo32_NoRep
+
+    cld
+    rep     outsd
+    jmp     @IoWriteFifo32_Done
+
+@IoWriteFifo32_NoRep:
+    jrcxz   @IoWriteFifo32_Done
+
+@IoWriteFifo32_Loop:
+    mov     dword [rsi], eax
+    out     dx, eax
+    add     rsi, 4
+    loop    @IoWriteFifo32_Loop
+
+@IoWriteFifo32_Done:
+    mov     rsi, r8             ; restore rsi
+    ret
+
-- 
2.7.4



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