[edk2-devel] [RFC PATCH v2 21/44] MdePkg: Add support for the XGETBV instruction

[Lendacky, Thomas]

From: Tom Lendacky <thomas.lendacky at amd.com>

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        | 16 ++++++++++++
 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, 141 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 14b3f5721101..ea3e284bf8bf 100644
--- a/MdePkg/Library/BaseLib/BaseLib.inf
+++ b/MdePkg/Library/BaseLib/BaseLib.inf
@@ -153,6 +153,7 @@ [Sources.Ia32]
   Ia32/EnableCache.c | MSFT
   Ia32/DisableCache.c | MSFT
   Ia32/VmgExit.nasm | MSFT
+  Ia32/XGetBv.nasm | MSFT
 
 
   Ia32/GccInline.c | GCC
@@ -288,6 +289,7 @@ [Sources.X64]
   X64/ReadCr0.nasm| MSFT
   X64/ReadEflags.nasm| MSFT
   X64/VmgExit.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 80bd5cf57a72..362bc2e05dbc 100644
--- a/MdePkg/Include/Library/BaseLib.h
+++ b/MdePkg/Include/Library/BaseLib.h
@@ -7893,6 +7893,22 @@ AsmVmgExit (
   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,
diff --git a/MdePkg/Library/BaseLib/Ia32/GccInline.c b/MdePkg/Library/BaseLib/Ia32/GccInline.c
index 55d2e12bcdc9..9db5e48d9899 100644
--- a/MdePkg/Library/BaseLib/Ia32/GccInline.c
+++ b/MdePkg/Library/BaseLib/Ia32/GccInline.c
@@ -1780,3 +1780,31 @@ AsmVmgExit (
 }
 
 
+/**
+  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 17539caa0798..0169382978ac 100644
--- a/MdePkg/Library/BaseLib/X64/GccInline.c
+++ b/MdePkg/Library/BaseLib/X64/GccInline.c
@@ -1815,3 +1815,33 @@ AsmVmgExit (
 }
 
 
+/**
+  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..8d14ba03d4a8
--- /dev/null
+++ b/MdePkg/Library/BaseLib/Ia32/XGetBv.nasm
@@ -0,0 +1,31 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (c) 2019, Advanced Micro Device, 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..239ecb58ab13
--- /dev/null
+++ b/MdePkg/Library/BaseLib/X64/XGetBv.nasm
@@ -0,0 +1,34 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (c) 2019, Advanced Micro Device, 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, 0x20
+    or      rax, rdx
+    ret
+
-- 
2.17.1


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