UefiPayloadPkg: Add SmmStoreLib

Implement all of the FVB protocol functions on top of the SmmStore
as a library. The library consumes the introduced gEfiSmmStoreInfoHobGuid.

The SMI handler uses a fixed communication buffer in reserved DRAM.
To initiate a transaction you must write to the I/O APM_CNT port.

Tests on Intel(R) Xeon(R) E-2288G CPU @ 3.70G showed that the SMI isn't
triggered with a probability of 1:40 of all cases when called in a tight
loop. The CPU continues running and the SMI is triggeres asynchronously
a few clock cycles later. coreboot only handels synchronous APM request
and does nothing on asynchronous APM triggers.

As there's no livesign from SMM it's impossible to tell if the handler
has run. Just wait a bit and try again to trigger a synchronous SMI.

Tests confirmed that out of 5 million tries the SMI is now always handled.

When a synchronous SMI happens with the correct write to the APM_CNT port,
the ebx register is checked first that it doesn't point to SMRAM.
If it doesn't it's used to read in the arguments that define a SmmStore
transaction.

The SMI handler will only operate on a predefined and memory mapped region in
the boot media.

Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>

UefiPayloadPkg/Include/Library/SmmStoreLib.h

@@ -0,0 +1,120 @@
+/** @file  SmmStoreLib.h
+
+  Copyright (c) 2022, 9elements GmbH<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef SMM_STORE_LIB_H_
+#define SMM_STORE_LIB_H_
+
+#include <Base.h>
+#include <Uefi/UefiBaseType.h>
+#include <Guid/SmmStoreInfoGuid.h>
+
+#define SMMSTORE_COMBUF_SIZE  16
+
+/**
+  Get the SmmStore block size
+
+  @param BlockSize    The pointer to store the block size in.
+
+**/
+EFI_STATUS
+SmmStoreLibGetBlockSize (
+  OUT UINTN  *BlockSize
+  );
+
+/**
+  Get the SmmStore number of blocks
+
+  @param NumBlocks    The pointer to store the number of blocks in.
+
+**/
+EFI_STATUS
+SmmStoreLibGetNumBlocks (
+  OUT UINTN  *NumBlocks
+  );
+
+/**
+  Get the SmmStore MMIO address
+
+  @param MmioAddress    The pointer to store the address in.
+
+**/
+EFI_STATUS
+SmmStoreLibGetMmioAddress (
+  OUT EFI_PHYSICAL_ADDRESS  *MmioAddress
+  );
+
+/**
+  Read from SmmStore
+
+  @param[in] Lba      The starting logical block index to read from.
+  @param[in] Offset   Offset into the block at which to begin reading.
+  @param[in] NumBytes On input, indicates the requested read size. On
+                      output, indicates the actual number of bytes read
+  @param[in] Buffer   Pointer to the buffer to read into.
+
+**/
+EFI_STATUS
+SmmStoreLibRead (
+  IN        EFI_LBA  Lba,
+  IN        UINTN    Offset,
+  IN        UINTN    *NumBytes,
+  IN        UINT8    *Buffer
+  );
+
+/**
+  Write to SmmStore
+
+  @param[in] Lba      The starting logical block index to write to.
+  @param[in] Offset   Offset into the block at which to begin writing.
+  @param[in] NumBytes On input, indicates the requested write size. On
+                      output, indicates the actual number of bytes written
+  @param[in] Buffer   Pointer to the data to write.
+
+**/
+EFI_STATUS
+SmmStoreLibWrite (
+  IN        EFI_LBA  Lba,
+  IN        UINTN    Offset,
+  IN        UINTN    *NumBytes,
+  IN        UINT8    *Buffer
+  );
+
+/**
+  Erase a block using the SmmStore
+
+  @param Lba    The logical block index to erase.
+
+**/
+EFI_STATUS
+SmmStoreLibEraseBlock (
+  IN         EFI_LBA  Lba
+  );
+
+/**
+  Initializes SmmStore support
+
+  @retval EFI_WRITE_PROTECTED   The SmmStore is not present.
+  @retval EFI_UNSUPPORTED       The SmmStoreInfo HOB wasn't found.
+  @retval EFI_SUCCESS           The SmmStore is supported.
+
+**/
+EFI_STATUS
+SmmStoreLibInitialize (
+  VOID
+  );
+
+/**
+  Denitializes SmmStore support
+**/
+VOID
+EFIAPI
+SmmStoreLibDeinitialize (
+  VOID
+  );
+
+#endif /* SMM_STORE_LIB_H_ */