[edk2-devel] [PATCH v3 02/11] UefiCpuPkg/VmgExitLib: Add interfaces to set/read GHCB ValidBitmap bits

[Dong, Eric]

Acked-by: Eric Dong <eric.dong at intel.com>

-----Original Message-----
From: Tom Lendacky <thomas.lendacky at amd.com> 
Sent: Thursday, October 29, 2020 10:18 PM
To: devel at edk2.groups.io
Cc: Brijesh Singh <brijesh.singh at amd.com>; Dong, Eric <eric.dong at intel.com>; Ni, Ray <ray.ni at intel.com>; Laszlo Ersek <lersek at redhat.com>; Kumar, Rahul1 <rahul1.kumar at intel.com>
Subject: [PATCH v3 02/11] UefiCpuPkg/VmgExitLib: Add interfaces to set/read GHCB ValidBitmap bits

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

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3008

In upcoming patches, the setting of the bits in the GHCB ValidBitmap will be performed in multiple places. In order to reduce code duplication, add an interface, VmgSetOffsetValid(), to VmgExitLib library to perform this function. Also, to keep management of the ValidBitmap within the library, add an inteface, VmgIsOffsetValid(), to return whether the bit in the ValidBitmap is set for a specified offset.

The new VmgSetOffsetValid() function is a VOID function and will be an empty function in the VmgExitLibNull implementation of the VmgExitLib library.

The new VmgIsOffsetValid() function returns a BOOLEAN to indicate if the offset is valid. This will always return FALSE in the VmgExitLibNull implementation of the VmgExitLib library.

Cc: Eric Dong <eric.dong at intel.com>
Cc: Ray Ni <ray.ni at intel.com>
Cc: Laszlo Ersek <lersek at redhat.com>
Cc: Rahul Kumar <rahul1.kumar at intel.com>
Reviewed-by: Laszlo Ersek <lersek at redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky at amd.com>
---
 UefiCpuPkg/Include/Library/VmgExitLib.h            | 37 +++++++++++++++++
 UefiCpuPkg/Library/VmgExitLibNull/VmgExitLibNull.c | 42 ++++++++++++++++++++
 2 files changed, 79 insertions(+)

diff --git a/UefiCpuPkg/Include/Library/VmgExitLib.h b/UefiCpuPkg/Include/Library/VmgExitLib.h
index 45fc27d35e29..07e8af6450b9 100644
--- a/UefiCpuPkg/Include/Library/VmgExitLib.h
+++ b/UefiCpuPkg/Include/Library/VmgExitLib.h
@@ -74,6 +74,43 @@ VmgDone (
   IN OUT GHCB                *Ghcb
   );
 
+/**
+  Marks a specified offset as valid in the GHCB.
+
+  The ValidBitmap area represents the areas of the GHCB that have been 
+ marked  valid. Set the bit in ValidBitmap for the input offset.
+
+  @param[in, out]  Ghcb       A pointer to the GHCB
+  @param[in]       Offset     Qword offset in the GHCB to mark valid
+
+**/
+VOID
+EFIAPI
+VmgSetOffsetValid (
+  IN OUT GHCB                *Ghcb,
+  IN     GHCB_REGISTER       Offset
+  );
+
+/**
+  Checks if a specified offset is valid in the GHCB.
+
+  The ValidBitmap area represents the areas of the GHCB that have been 
+ marked  valid. Return whether the bit in the ValidBitmap is set for the input offset.
+
+  @param[in]  Ghcb            A pointer to the GHCB
+  @param[in]  Offset          Qword offset in the GHCB to mark valid
+
+  @retval TRUE                Offset is marked valid in the GHCB
+  @retval FALSE               Offset is not marked valid in the GHCB
+
+**/
+BOOLEAN
+EFIAPI
+VmgIsOffsetValid (
+  IN GHCB                    *Ghcb,
+  IN GHCB_REGISTER           Offset
+  );
+
 /**
   Handle a #VC exception.
 
diff --git a/UefiCpuPkg/Library/VmgExitLibNull/VmgExitLibNull.c b/UefiCpuPkg/Library/VmgExitLibNull/VmgExitLibNull.c
index bb265e1700d2..b47e282aff82 100644
--- a/UefiCpuPkg/Library/VmgExitLibNull/VmgExitLibNull.c
+++ b/UefiCpuPkg/Library/VmgExitLibNull/VmgExitLibNull.c
@@ -89,6 +89,48 @@ VmgDone (
 {
 }
 
+/**
+  Marks a field at the specified offset as valid in the GHCB.
+
+  The ValidBitmap area represents the areas of the GHCB that have been 
+ marked  valid. Set the bit in ValidBitmap for the input offset.
+
+  @param[in, out] Ghcb    Pointer to the Guest-Hypervisor Communication Block
+  @param[in]      Offset  Qword offset in the GHCB to mark valid
+
+**/
+VOID
+EFIAPI
+VmgSetOffsetValid (
+  IN OUT GHCB                *Ghcb,
+  IN     GHCB_REGISTER       Offset
+  )
+{
+}
+
+/**
+  Checks if a specified offset is valid in the GHCB.
+
+  The ValidBitmap area represents the areas of the GHCB that have been 
+ marked  valid. Return whether the bit in the ValidBitmap is set for the input offset.
+
+  @param[in]  Ghcb            A pointer to the GHCB
+  @param[in]  Offset          Qword offset in the GHCB to mark valid
+
+  @retval TRUE                Offset is marked valid in the GHCB
+  @retval FALSE               Offset is not marked valid in the GHCB
+
+**/
+BOOLEAN
+EFIAPI
+VmgIsOffsetValid (
+  IN GHCB                    *Ghcb,
+  IN GHCB_REGISTER           Offset
+  )
+{
+  return FALSE;
+}
+
 /**
   Handle a #VC exception.
 
--
2.28.0



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