[edk2-devel] [PATCH v7 06/43] MdePkg/BaseLib: Add support for the XGETBV instruction

[Lendacky, Thomas]

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198

Under SEV-ES, a CPUID instruction requires the current value of the XCR0
register. In order to retrieve that value, the XGETBV instruction needs
to be executed.

Provide the necessary support to execute the XGETBV instruction.

Cc: Michael D Kinney <michael.d.kinney at intel.com>
Cc: Liming Gao <liming.gao at intel.com>
Signed-off-by: Tom Lendacky <thomas.lendacky at amd.com>
---
 MdePkg/Library/BaseLib/BaseLib.inf      |  2 ++
 MdePkg/Include/Library/BaseLib.h        | 17 +++++++++++++
 MdePkg/Library/BaseLib/Ia32/GccInline.c | 28 ++++++++++++++++++++
 MdePkg/Library/BaseLib/X64/GccInline.c  | 30 ++++++++++++++++++++++
 MdePkg/Library/BaseLib/Ia32/XGetBv.nasm | 31 ++++++++++++++++++++++
 MdePkg/Library/BaseLib/X64/XGetBv.nasm  | 34 +++++++++++++++++++++++++
 6 files changed, 142 insertions(+)
 create mode 100644 MdePkg/Library/BaseLib/Ia32/XGetBv.nasm
 create mode 100644 MdePkg/Library/BaseLib/X64/XGetBv.nasm

diff --git a/MdePkg/Library/BaseLib/BaseLib.inf b/MdePkg/Library/BaseLib/BaseLib.inf
index 3586beb0ab5c..d7a1dd017e95 100644
--- a/MdePkg/Library/BaseLib/BaseLib.inf
+++ b/MdePkg/Library/BaseLib/BaseLib.inf
@@ -152,6 +152,7 @@ [Sources.Ia32]
   Ia32/ARShiftU64.c | MSFT
   Ia32/EnableCache.c | MSFT
   Ia32/DisableCache.c | MSFT
+  Ia32/XGetBv.nasm | MSFT
 
 
   Ia32/GccInline.c | GCC
@@ -286,6 +287,7 @@ [Sources.X64]
   X64/ReadCr2.nasm| MSFT
   X64/ReadCr0.nasm| MSFT
   X64/ReadEflags.nasm| MSFT
+  X64/XGetBv.nasm | MSFT
 
 
   X64/Non-existing.c
diff --git a/MdePkg/Include/Library/BaseLib.h b/MdePkg/Include/Library/BaseLib.h
index ecadff8b235e..d0cbb52ed8f9 100644
--- a/MdePkg/Include/Library/BaseLib.h
+++ b/MdePkg/Include/Library/BaseLib.h
@@ -7889,6 +7889,23 @@ AsmLfence (
   VOID
   );
 
+/**
+  Executes a XGETBV instruction
+
+  Executes a XGETBV instruction. This function is only available on IA-32 and
+  x64.
+
+  @param[in] Index        Extended control register index
+
+  @retval                 The current value of the extended control register
+**/
+UINT64
+EFIAPI
+AsmXGetBv (
+  IN UINT32  Index
+  );
+
+
 /**
   Patch the immediate operand of an IA32 or X64 instruction such that the byte,
   word, dword or qword operand is encoded at the end of the instruction's
diff --git a/MdePkg/Library/BaseLib/Ia32/GccInline.c b/MdePkg/Library/BaseLib/Ia32/GccInline.c
index 5287200f8754..591f0bb0e097 100644
--- a/MdePkg/Library/BaseLib/Ia32/GccInline.c
+++ b/MdePkg/Library/BaseLib/Ia32/GccInline.c
@@ -1763,3 +1763,31 @@ AsmFlushCacheLine (
 }
 
 
+/**
+  Executes a XGETBV instruction
+
+  Executes a XGETBV instruction. This function is only available on IA-32 and
+  x64.
+
+  @param[in] Index        Extended control register index
+
+  @retval                 The current value of the extended control register
+**/
+UINT64
+EFIAPI
+AsmXGetBv (
+  IN UINT32 Index
+  )
+{
+  UINT64 Data;
+
+  __asm__ __volatile__ (
+    "xgetbv"
+    : "=A" (Data)
+    : "c"  (Index)
+    );
+
+  return Data;
+}
+
+
diff --git a/MdePkg/Library/BaseLib/X64/GccInline.c b/MdePkg/Library/BaseLib/X64/GccInline.c
index 154ce1f57e92..3eed1205adb2 100644
--- a/MdePkg/Library/BaseLib/X64/GccInline.c
+++ b/MdePkg/Library/BaseLib/X64/GccInline.c
@@ -1798,3 +1798,33 @@ AsmFlushCacheLine (
 }
 
 
+/**
+  Executes a XGETBV instruction
+
+  Executes a XGETBV instruction. This function is only available on IA-32 and
+  x64.
+
+  @param[in] Index        Extended control register index
+
+  @retval                 The current value of the extended control register
+**/
+UINT64
+EFIAPI
+AsmXGetBv (
+  IN UINT32 Index
+  )
+{
+  UINT32 LowData;
+  UINT32 HighData;
+
+  __asm__ __volatile__ (
+    "xgetbv"
+    : "=a" (LowData),
+      "=d" (HighData)
+    : "c"  (Index)
+    );
+
+  return (((UINT64)HighData) << 32) | LowData;
+}
+
+
diff --git a/MdePkg/Library/BaseLib/Ia32/XGetBv.nasm b/MdePkg/Library/BaseLib/Ia32/XGetBv.nasm
new file mode 100644
index 000000000000..b6dee38af029
--- /dev/null
+++ b/MdePkg/Library/BaseLib/Ia32/XGetBv.nasm
@@ -0,0 +1,31 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (c) 2020, Advanced Micro Devices, Inc. All rights reserved.<BR>
+; SPDX-License-Identifier: BSD-2-Clause-Patent
+;
+; Module Name:
+;
+;   XGetBv.Asm
+;
+; Abstract:
+;
+;   AsmXgetBv function
+;
+; Notes:
+;
+;------------------------------------------------------------------------------
+
+    SECTION .text
+
+;------------------------------------------------------------------------------
+; UINT64
+; EFIAPI
+; AsmXGetBv (
+;   IN UINT32  Index
+;   );
+;------------------------------------------------------------------------------
+global ASM_PFX(AsmXGetBv)
+ASM_PFX(AsmXGetBv):
+    mov     ecx, [esp + 4]
+    xgetbv
+    ret
diff --git a/MdePkg/Library/BaseLib/X64/XGetBv.nasm b/MdePkg/Library/BaseLib/X64/XGetBv.nasm
new file mode 100644
index 000000000000..f3aec43e6813
--- /dev/null
+++ b/MdePkg/Library/BaseLib/X64/XGetBv.nasm
@@ -0,0 +1,34 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (c) 2020, Advanced Micro Devices, Inc. All rights reserved.<BR>
+; SPDX-License-Identifier: BSD-2-Clause-Patent
+;
+; Module Name:
+;
+;   XGetBv.Asm
+;
+; Abstract:
+;
+;   AsmXgetBv function
+;
+; Notes:
+;
+;------------------------------------------------------------------------------
+
+    DEFAULT REL
+    SECTION .text
+
+;------------------------------------------------------------------------------
+; UINT64
+; EFIAPI
+; AsmXGetBv (
+;   IN UINT32  Index
+;   );
+;------------------------------------------------------------------------------
+global ASM_PFX(AsmXGetBv)
+ASM_PFX(AsmXGetBv):
+    xgetbv
+    shl     rdx, 32
+    or      rax, rdx
+    ret
+
-- 
2.17.1


-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.

View/Reply Online (#57837): https://edk2.groups.io/g/devel/message/57837
Mute This Topic: https://groups.io/mt/73201895/1813853
Group Owner: devel+owner at edk2.groups.io
Unsubscribe: https://edk2.groups.io/g/devel/unsub  [edk2-devel-archive at redhat.com]
-=-=-=-=-=-=-=-=-=-=-=-