QemuFwCfgPei.c

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#include <PiPei.h>
#include <Library/BaseLib.h>
#include <Library/DebugLib.h>
#include <Library/HobLib.h>
#include <Library/IoLib.h>
#include <Library/PlatformInitLib.h>
#include <Library/QemuFwCfgLib.h>
#include <WorkArea.h>
 
#include "QemuFwCfgLibInternal.h"
 
STATIC
BOOLEAN
QemuFwCfgIsCcGuest (
  VOID
  )
{
  CONFIDENTIAL_COMPUTING_WORK_AREA_HEADER  *CcWorkAreaHeader;
 
  CcWorkAreaHeader = (CONFIDENTIAL_COMPUTING_WORK_AREA_HEADER *)FixedPcdGet32 (PcdOvmfWorkAreaBase);
  return (CcWorkAreaHeader != NULL && CcWorkAreaHeader->GuestType != CcGuestTypeNonEncrypted);
}
 
BOOLEAN
EFIAPI
QemuFwCfgIsAvailable (
  VOID
  )
{
  return InternalQemuFwCfgIsAvailable ();
}
 
STATIC
VOID
QemuFwCfgProbe (
  BOOLEAN  *Supported,
  BOOLEAN  *DmaSupported
  )
{
  UINT32   Signature;
  UINT32   Revision;
  BOOLEAN  CcGuest;
 
  // Use direct Io* calls for probing to avoid recursion.
  IoWrite16 (FW_CFG_IO_SELECTOR, (UINT16)QemuFwCfgItemSignature);
  IoReadFifo8 (FW_CFG_IO_DATA, sizeof Signature, &Signature);
  IoWrite16 (FW_CFG_IO_SELECTOR, (UINT16)QemuFwCfgItemInterfaceVersion);
  IoReadFifo8 (FW_CFG_IO_DATA, sizeof Revision, &Revision);
  CcGuest = QemuFwCfgIsCcGuest ();
 
  *Supported    = FALSE;
  *DmaSupported = FALSE;
  if ((Signature == SIGNATURE_32 ('Q', 'E', 'M', 'U')) && (Revision >= 1)) {
    *Supported = TRUE;
    if ((Revision & FW_CFG_F_DMA) && !CcGuest) {
      *DmaSupported = TRUE;
    }
  }
 
  DEBUG ((
    DEBUG_INFO,
    "%a: Supported %d, DMA %d\n",
    __func__,
    *Supported,
    *DmaSupported
    ));
}
 
STATIC
EFI_HOB_PLATFORM_INFO *
QemuFwCfgGetPlatformInfo (
  VOID
  )
{
  EFI_HOB_PLATFORM_INFO  *PlatformInfoHob;
  EFI_HOB_GUID_TYPE      *GuidHob;
 
  GuidHob = GetFirstGuidHob (&gUefiOvmfPkgPlatformInfoGuid);
  if (GuidHob == NULL) {
    return NULL;
  }
 
  PlatformInfoHob = (EFI_HOB_PLATFORM_INFO *)GET_GUID_HOB_DATA (GuidHob);
 
  if (!PlatformInfoHob->QemuFwCfgChecked) {
    QemuFwCfgProbe (
      &PlatformInfoHob->QemuFwCfgSupported,
      &PlatformInfoHob->QemuFwCfgDmaSupported
      );
    PlatformInfoHob->QemuFwCfgChecked = TRUE;
  }
 
  return PlatformInfoHob;
}
 
RETURN_STATUS
EFIAPI
QemuFwCfgInitialize (
  VOID
  )
{
  return RETURN_SUCCESS;
}
 
BOOLEAN
InternalQemuFwCfgIsAvailable (
  VOID
  )
{
  EFI_HOB_PLATFORM_INFO  *PlatformInfoHob = QemuFwCfgGetPlatformInfo ();
 
  return PlatformInfoHob->QemuFwCfgSupported;
}
 
BOOLEAN
InternalQemuFwCfgDmaIsAvailable (
  VOID
  )
{
  EFI_HOB_PLATFORM_INFO  *PlatformInfoHob = QemuFwCfgGetPlatformInfo ();
 
  return PlatformInfoHob->QemuFwCfgDmaSupported;
}
 
VOID
InternalQemuFwCfgDmaBytes (
  IN     UINT32  Size,
  IN OUT VOID    *Buffer OPTIONAL,
  IN     UINT32  Control
  )
{
  volatile FW_CFG_DMA_ACCESS  Access;
  UINT32                      AccessHigh, AccessLow;
  UINT32                      Status;
 
  ASSERT (
    Control == FW_CFG_DMA_CTL_WRITE || Control == FW_CFG_DMA_CTL_READ ||
    Control == FW_CFG_DMA_CTL_SKIP
    );
 
  if (Size == 0) {
    return;
  }
 
  //
  // TDX does not support DMA operations in PEI stage, we should
  // not have reached here.
  //
  ASSERT (!QemuFwCfgIsCcGuest ());
 
  Access.Control = SwapBytes32 (Control);
  Access.Length  = SwapBytes32 (Size);
  Access.Address = SwapBytes64 ((UINTN)Buffer);
 
  //
  // Delimit the transfer from (a) modifications to Access, (b) in case of a
  // write, from writes to Buffer by the caller.
  //
  MemoryFence ();
 
  //
  // Start the transfer.
  //
  AccessHigh = (UINT32)RShiftU64 ((UINTN)&Access, 32);
  AccessLow  = (UINT32)(UINTN)&Access;
  IoWrite32 (FW_CFG_IO_DMA_ADDRESS, SwapBytes32 (AccessHigh));
  IoWrite32 (FW_CFG_IO_DMA_ADDRESS + 4, SwapBytes32 (AccessLow));
 
  //
  // Don't look at Access.Control before starting the transfer.
  //
  MemoryFence ();
 
  //
  // Wait for the transfer to complete.
  //
  do {
    Status = SwapBytes32 (Access.Control);
    ASSERT ((Status & FW_CFG_DMA_CTL_ERROR) == 0);
  } while (Status != 0);
 
  //
  // After a read, the caller will want to use Buffer.
  //
  MemoryFence ();
}