QemuFlashSmm.c

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#include <Library/BaseMemoryLib.h>
#include <Library/DebugLib.h>
#include <Library/PcdLib.h>
#include <Library/MemEncryptSevLib.h>
 
#include "QemuFlash.h"
 
VOID
QemuFlashBeforeProbe (
  IN  EFI_PHYSICAL_ADDRESS  BaseAddress,
  IN  UINTN                 FdBlockSize,
  IN  UINTN                 FdBlockCount
  )
{
  EFI_STATUS  Status;
 
  ASSERT (FeaturePcdGet (PcdSmmSmramRequire));
 
  if (!MemEncryptSevIsEnabled ()) {
    return;
  }
 
  //
  // When SEV is enabled, AmdSevDxe runs early in DXE phase and clears the
  // C-bit from the NonExistent entry -- which is later split and accommodate
  // the flash MMIO but the driver runs in non SMM context hence it cleared the
  // flash ranges from non SMM page table. When SMM is enabled, the flash
  // services are accessed from the SMM mode hence we explicitly clear the
  // C-bit on flash ranges from SMM page table.
  //
 
  Status = MemEncryptSevClearMmioPageEncMask (
             0,
             BaseAddress,
             EFI_SIZE_TO_PAGES (FdBlockSize * FdBlockCount)
             );
  ASSERT_EFI_ERROR (Status);
}
 
VOID
QemuFlashPtrWrite (
  IN        volatile UINT8  *Ptr,
  IN        UINT8           Value
  )
{
  *Ptr = Value;
}