PrmPkg: Add ALLOCATE_CONTEXT_BUFFER_IN_FW build option

There's currently two approaches being considered for how to allocate the
context buffer passed to PRM handlers:

1. The context buffer is allocated and populated in firmware. As such, the
   FW converts all pointers internal to the buffer to virtual memory
   addresses at the virtual address change event. A single context buffer
   pointer is given to the OS via the PRM ACPI table and the OS converts
   this single physical address to a virtual address when it passes the
   context buffer as a pointer to PRM handlers.

2. The context buffer is allocated and populated in the OS. The OS gets
   all the information needed to populate the context buffer from other
   pre-existing resources (mainly physical addresses in the PRM ACPI
   table). The OS converts all the physical addresses to virtual addresses,
   allocates the context buffer instances, and fills in the information.
   The OS passes the context buffer virtual address to PRM handlers.

The prior behavior was (1). The current POR behavior has moved to (2).
Until (2) is used more widely, it can be kept around with fairly minimal
overhead via a build flag in a few places.

So the default behavior is now (2) (the expected permanent behavior) with
(1) easily enabled by defining "ALLOCATE_CONTEXT_BUFFER_IN_FW" in the
compiler defined macros. A DSC define was added in PrmPkg.dsc to set this
compiler macro in the package  build.

At some point in the future, all code (and some peripheral code)
surrounded with this build flag can be removed if (2) is fully
decided upon.

Cc: Andrew Fish <afish@apple.com>
Cc: Kang Gao <kang.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Michael Kubacki <michael.kubacki@microsoft.com>
Cc: Leif Lindholm <leif@nuviainc.com>
Cc: Benjamin You <benjamin.you@intel.com>
Cc: Liu Yun <yun.y.liu@intel.com>
Cc: Ankit Sinha <ankit.sinha@intel.com>
Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
Acked-by: Michael D Kinney <michael.d.kinney@intel.com>
Acked-by: Liming Gao <gaoliming@byosoft.com.cn>
Acked-by: Leif Lindholm <quic_llindhol@quicinc.com>
Reviewed-by: Ankit Sinha <ankit.sinha@intel.com>

2 files changed, 9 insertions, 1 deletions

diff --git a/PrmPkg/PrmLoaderDxe/PrmAcpiTable.h b/PrmPkg/PrmLoaderDxe/PrmAcpiTable.h
index 6b9099ca7b..8a9c82347d 100644
--- a/PrmPkg/PrmLoaderDxe/PrmAcpiTable.h
+++ b/PrmPkg/PrmLoaderDxe/PrmAcpiTable.h
@@ -30,8 +30,10 @@ typedef struct {
   UINT16                              StructureLength;            ///< Length in bytes of this structure

   GUID                                Identifier;                 ///< GUID of the PRM handler for this structure

   UINT64                              PhysicalAddress;            ///< Physical address of this PRM handler

+#ifdef ALLOCATE_CONTEXT_BUFFER_IN_FW

   UINT64                              PrmContextBuffer;           ///< Physical address of the context buffer for this

                                                                   ///< PRM handler (PRM_CONTEXT_BUFFER *)

+#else

   UINT64                              StaticDataBuffer;           ///< Physical address of the static data buffer for

                                                                   ///< this PRM handler (PRM_DATA_BUFFER *)

   UINT64                              AcpiParameterBuffer;        ///< Physical address of the parameter buffer

@@ -39,6 +41,8 @@ typedef struct {
                                                                   ///< that is only used in the case of _DSM invocation.

                                                                   ///< If _DSM invocation is not used, this value is

                                                                   ///< ignored.

+#endif

+

 } PRM_HANDLER_INFORMATION_STRUCT;

 

 typedef struct {

diff --git a/PrmPkg/PrmLoaderDxe/PrmLoaderDxe.c b/PrmPkg/PrmLoaderDxe/PrmLoaderDxe.c
index b43e6d6bf0..85fffdcbd9 100644
--- a/PrmPkg/PrmLoaderDxe/PrmLoaderDxe.c
+++ b/PrmPkg/PrmLoaderDxe/PrmLoaderDxe.c
@@ -755,7 +755,11 @@ ProcessPrmModules (
                   &CurrentContextBuffer

                   );

       if (!EFI_ERROR (Status)) {

-        CurrentHandlerInfoStruct->PrmContextBuffer = (UINT64) CurrentContextBuffer;

+#ifdef ALLOCATE_CONTEXT_BUFFER_IN_FW

+        CurrentHandlerInfoStruct->PrmContextBuffer = (UINT64) (UINTN) CurrentContextBuffer;

+#else

+        CurrentHandlerInfoStruct->StaticDataBuffer = (UINT64) (UINTN) CurrentContextBuffer->StaticDataBuffer;

+#endif

       }

 

       Status =  GetExportEntryAddress (