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  3. [edk2] [PATCH 0/2] MdePkg, OvmfPkg: fix IoWriteFifo8(), and print debug messages with it
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[edk2] [PATCH 1/2] MdePkg/BaseIoLibIntrinsic: fix SEV (=unrolled) variants of IoWriteFifoXX()

Laszlo Ersek posted 2 patches 7 years, 3 months ago
[edk2] [PATCH 1/2] MdePkg/BaseIoLibIntrinsic: fix SEV (=unrolled) variants of IoWriteFifoXX()
Posted by Laszlo Ersek 7 years, 3 months ago 
In commit b6d11d7c4678 ("MdePkg: BaseIoLibIntrinsic (IoLib class)
library", 2017-04-12), the MOV instructions in the write loops were
probably copied from the read loops. However, the operand order was not
adjusted.

As a result, the IoWriteFifoXX() routines, when invoked in SEV guests, now
overwrite the source buffer with value 0x01 / 0x0001 / 0x00000001 -- the
SevNoRepIo() function returns value 1 in EAX, in SEV guests --, and write
the same value to the target IO port.

Fix this by putting the target operand (AL / AX / EAX) first, and the
source operand (BYTE / WORD / DWORD [ESI/RSI]) second.

Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Fixes: b6d11d7c467810ea7f2e2eda46ef0bdc57bf1475
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
---
 MdePkg/Library/BaseIoLibIntrinsic/Ia32/IoFifoSev.nasm | 6 +++---
 MdePkg/Library/BaseIoLibIntrinsic/X64/IoFifoSev.nasm  | 6 +++---
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/MdePkg/Library/BaseIoLibIntrinsic/Ia32/IoFifoSev.nasm b/MdePkg/Library/BaseIoLibIntrinsic/Ia32/IoFifoSev.nasm
index 3e80c17d04a3..4b2af807cff8 100644
--- a/MdePkg/Library/BaseIoLibIntrinsic/Ia32/IoFifoSev.nasm
+++ b/MdePkg/Library/BaseIoLibIntrinsic/Ia32/IoFifoSev.nasm
@@ -212,7 +212,7 @@ ASM_PFX(IoWriteFifo8):
     jecxz   @IoWriteFifo8_Done
 
 @IoWriteFifo8_Loop:
-    mov     byte [esi], al
+    mov     al, byte [esi]
     out     dx, al
     inc     esi
     loop    @IoWriteFifo8_Loop
@@ -250,7 +250,7 @@ ASM_PFX(IoWriteFifo16):
     jecxz   @IoWriteFifo16_Done
 
 @IoWriteFifo16_Loop:
-    mov     word [esi], ax
+    mov     ax, word [esi]
     out     dx, ax
     add     esi, 2
     loop    @IoWriteFifo16_Loop
@@ -288,7 +288,7 @@ ASM_PFX(IoWriteFifo32):
     jecxz   @IoWriteFifo32_Done
 
 @IoWriteFifo32_Loop:
-    mov     dword [esi], eax
+    mov     eax, dword [esi]
     out     dx, eax
     add     esi, 4
     loop    @IoWriteFifo32_Loop
diff --git a/MdePkg/Library/BaseIoLibIntrinsic/X64/IoFifoSev.nasm b/MdePkg/Library/BaseIoLibIntrinsic/X64/IoFifoSev.nasm
index 26e016625b72..4d86a6cd5330 100644
--- a/MdePkg/Library/BaseIoLibIntrinsic/X64/IoFifoSev.nasm
+++ b/MdePkg/Library/BaseIoLibIntrinsic/X64/IoFifoSev.nasm
@@ -205,7 +205,7 @@ ASM_PFX(IoWriteFifo8):
     jrcxz   @IoWriteFifo8_Done
 
 @IoWriteFifo8_Loop:
-    mov     byte [rsi], al
+    mov     al, byte [rsi]
     out     dx, al
     inc     rsi
     loop    @IoWriteFifo8_Loop
@@ -241,7 +241,7 @@ ASM_PFX(IoWriteFifo16):
     jrcxz   @IoWriteFifo16_Done
 
 @IoWriteFifo16_Loop:
-    mov     word [rsi], ax
+    mov     ax, word [rsi]
     out     dx, ax
     add     rsi, 2
     loop    @IoWriteFifo16_Loop
@@ -277,7 +277,7 @@ ASM_PFX(IoWriteFifo32):
     jrcxz   @IoWriteFifo32_Done
 
 @IoWriteFifo32_Loop:
-    mov     dword [rsi], eax
+    mov     eax, dword [rsi]
     out     dx, eax
     add     rsi, 4
     loop    @IoWriteFifo32_Loop
-- 
2.14.1.3.gb7cf6e02401b


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Re: [edk2] [PATCH 1/2] MdePkg/BaseIoLibIntrinsic: fix SEV (=unrolled) variants of IoWriteFifoXX()
Posted by Gao, Liming 7 years, 3 months ago 
Reviewed-by: Liming Gao <liming.gao@intel.com>

>-----Original Message-----
>From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of
>Laszlo Ersek
>Sent: Monday, September 04, 2017 11:57 PM
>To: edk2-devel-01 <edk2-devel@lists.01.org>
>Cc: Kinney, Michael D <michael.d.kinney@intel.com>; Justen, Jordan L
><jordan.l.justen@intel.com>; Gao, Liming <liming.gao@intel.com>
>Subject: [edk2] [PATCH 1/2] MdePkg/BaseIoLibIntrinsic: fix SEV (=unrolled)
>variants of IoWriteFifoXX()
>
>In commit b6d11d7c4678 ("MdePkg: BaseIoLibIntrinsic (IoLib class)
>library", 2017-04-12), the MOV instructions in the write loops were
>probably copied from the read loops. However, the operand order was not
>adjusted.
>
>As a result, the IoWriteFifoXX() routines, when invoked in SEV guests, now
>overwrite the source buffer with value 0x01 / 0x0001 / 0x00000001 -- the
>SevNoRepIo() function returns value 1 in EAX, in SEV guests --, and write
>the same value to the target IO port.
>
>Fix this by putting the target operand (AL / AX / EAX) first, and the
>source operand (BYTE / WORD / DWORD [ESI/RSI]) second.
>
>Cc: Brijesh Singh <brijesh.singh@amd.com>
>Cc: Jordan Justen <jordan.l.justen@intel.com>
>Cc: Liming Gao <liming.gao@intel.com>
>Cc: Michael D Kinney <michael.d.kinney@intel.com>
>Fixes: b6d11d7c467810ea7f2e2eda46ef0bdc57bf1475
>Contributed-under: TianoCore Contribution Agreement 1.1
>Signed-off-by: Laszlo Ersek <lersek@redhat.com>
>---
> MdePkg/Library/BaseIoLibIntrinsic/Ia32/IoFifoSev.nasm | 6 +++---
> MdePkg/Library/BaseIoLibIntrinsic/X64/IoFifoSev.nasm  | 6 +++---
> 2 files changed, 6 insertions(+), 6 deletions(-)
>
>diff --git a/MdePkg/Library/BaseIoLibIntrinsic/Ia32/IoFifoSev.nasm
>b/MdePkg/Library/BaseIoLibIntrinsic/Ia32/IoFifoSev.nasm
>index 3e80c17d04a3..4b2af807cff8 100644
>--- a/MdePkg/Library/BaseIoLibIntrinsic/Ia32/IoFifoSev.nasm
>+++ b/MdePkg/Library/BaseIoLibIntrinsic/Ia32/IoFifoSev.nasm
>@@ -212,7 +212,7 @@ ASM_PFX(IoWriteFifo8):
>     jecxz   @IoWriteFifo8_Done
>
> @IoWriteFifo8_Loop:
>-    mov     byte [esi], al
>+    mov     al, byte [esi]
>     out     dx, al
>     inc     esi
>     loop    @IoWriteFifo8_Loop
>@@ -250,7 +250,7 @@ ASM_PFX(IoWriteFifo16):
>     jecxz   @IoWriteFifo16_Done
>
> @IoWriteFifo16_Loop:
>-    mov     word [esi], ax
>+    mov     ax, word [esi]
>     out     dx, ax
>     add     esi, 2
>     loop    @IoWriteFifo16_Loop
>@@ -288,7 +288,7 @@ ASM_PFX(IoWriteFifo32):
>     jecxz   @IoWriteFifo32_Done
>
> @IoWriteFifo32_Loop:
>-    mov     dword [esi], eax
>+    mov     eax, dword [esi]
>     out     dx, eax
>     add     esi, 4
>     loop    @IoWriteFifo32_Loop
>diff --git a/MdePkg/Library/BaseIoLibIntrinsic/X64/IoFifoSev.nasm
>b/MdePkg/Library/BaseIoLibIntrinsic/X64/IoFifoSev.nasm
>index 26e016625b72..4d86a6cd5330 100644
>--- a/MdePkg/Library/BaseIoLibIntrinsic/X64/IoFifoSev.nasm
>+++ b/MdePkg/Library/BaseIoLibIntrinsic/X64/IoFifoSev.nasm
>@@ -205,7 +205,7 @@ ASM_PFX(IoWriteFifo8):
>     jrcxz   @IoWriteFifo8_Done
>
> @IoWriteFifo8_Loop:
>-    mov     byte [rsi], al
>+    mov     al, byte [rsi]
>     out     dx, al
>     inc     rsi
>     loop    @IoWriteFifo8_Loop
>@@ -241,7 +241,7 @@ ASM_PFX(IoWriteFifo16):
>     jrcxz   @IoWriteFifo16_Done
>
> @IoWriteFifo16_Loop:
>-    mov     word [rsi], ax
>+    mov     ax, word [rsi]
>     out     dx, ax
>     add     rsi, 2
>     loop    @IoWriteFifo16_Loop
>@@ -277,7 +277,7 @@ ASM_PFX(IoWriteFifo32):
>     jrcxz   @IoWriteFifo32_Done
>
> @IoWriteFifo32_Loop:
>-    mov     dword [rsi], eax
>+    mov     eax, dword [rsi]
>     out     dx, eax
>     add     rsi, 4
>     loop    @IoWriteFifo32_Loop
>--
>2.14.1.3.gb7cf6e02401b
>
>
>_______________________________________________
>edk2-devel mailing list
>edk2-devel@lists.01.org
>https://lists.01.org/mailman/listinfo/edk2-devel
_______________________________________________
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https://lists.01.org/mailman/listinfo/edk2-devel
Re: [edk2] [PATCH 1/2] MdePkg/BaseIoLibIntrinsic: fix SEV (=unrolled) variants of IoWriteFifoXX()
Posted by Brijesh Singh 7 years, 3 months ago 

On 09/04/2017 10:57 AM, Laszlo Ersek wrote:
> In commit b6d11d7c4678 ("MdePkg: BaseIoLibIntrinsic (IoLib class)
> library", 2017-04-12), the MOV instructions in the write loops were
> probably copied from the read loops. However, the operand order was not
> adjusted.
> 
> As a result, the IoWriteFifoXX() routines, when invoked in SEV guests, now
> overwrite the source buffer with value 0x01 / 0x0001 / 0x00000001 -- the
> SevNoRepIo() function returns value 1 in EAX, in SEV guests --, and write
> the same value to the target IO port.
> 
> Fix this by putting the target operand (AL / AX / EAX) first, and the
> source operand (BYTE / WORD / DWORD [ESI/RSI]) second.
> 
> Cc: Brijesh Singh <brijesh.singh@amd.com>
> Cc: Jordan Justen <jordan.l.justen@intel.com>
> Cc: Liming Gao <liming.gao@intel.com>
> Cc: Michael D Kinney <michael.d.kinney@intel.com>
> Fixes: b6d11d7c467810ea7f2e2eda46ef0bdc57bf1475
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Laszlo Ersek <lersek@redhat.com>


Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
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Patchew 2.1-devel-8c64711

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