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/** @file
QemuFwCfg cached feature related functions.
Copyright (c) 2025, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include <Uefi.h>
#include <Library/BaseLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/DebugLib.h>
#include <Library/QemuFwCfgLib.h>
#include "QemuFwCfgLibInternal.h"
/**
Get the pointer to the cached fw_cfg item.
@param[in] Item The fw_cfg item to be retrieved.
@retval FW_CFG_CACHED_ITEM Pointer to the cached fw_cfg item.
@retval NULL The fw_cfg item is not cached.
**/
FW_CFG_CACHED_ITEM *
InternalQemuFwCfgItemCached (
IN FIRMWARE_CONFIG_ITEM Item
)
{
BOOLEAN Cached;
FW_CFG_CACHED_ITEM *CachedItem;
UINT16 SelectItem;
EFI_PEI_HOB_POINTERS Hob;
FW_CFG_CACHED_ITEM *FwCfgCachedItem;
#ifdef TDX_PEI_LESS_BOOT
if (InternalQemuFwCfgCheckOvmfWorkArea () == FALSE) {
return NULL;
}
#endif
SelectItem = (UINT16)(UINTN)Item;
Hob.Raw = GetFirstGuidHob (&gOvmfFwCfgInfoHobGuid);
Cached = FALSE;
CachedItem = NULL;
while (Hob.Raw != NULL) {
FwCfgCachedItem = GET_GUID_HOB_DATA (Hob);
if ((SelectItem == FwCfgCachedItem->FwCfgItem) && (FwCfgCachedItem->DataSize != 0)) {
Cached = TRUE;
CachedItem = FwCfgCachedItem;
break;
}
Hob.Raw = GET_NEXT_HOB (Hob);
Hob.Raw = GetNextGuidHob (&gOvmfFwCfgInfoHobGuid, Hob.Raw);
}
return Cached ? CachedItem : NULL;
}
/**
Clear the QEMU_FW_CFG_WORK_AREA.
**/
VOID
InternalQemuFwCfgCacheResetWorkArea (
VOID
)
{
QEMU_FW_CFG_WORK_AREA *QemuFwCfgWorkArea;
QemuFwCfgWorkArea = InternalQemuFwCfgCacheGetWorkArea ();
if (QemuFwCfgWorkArea != NULL) {
QemuFwCfgWorkArea->FwCfgItem = 0;
QemuFwCfgWorkArea->Offset = 0;
QemuFwCfgWorkArea->Reading = FALSE;
}
}
/**
Check if reading from FwCfgCache is ongoing.
@retval TRUE Reading from FwCfgCache is ongoing.
@retval FALSE Reading from FwCfgCache is not ongoing.
**/
BOOLEAN
InternalQemuFwCfgCacheReading (
VOID
)
{
BOOLEAN Reading;
QEMU_FW_CFG_WORK_AREA *QemuFwCfgWorkArea;
Reading = FALSE;
QemuFwCfgWorkArea = InternalQemuFwCfgCacheGetWorkArea ();
if (QemuFwCfgWorkArea != NULL) {
Reading = QemuFwCfgWorkArea->Reading;
}
return Reading;
}
BOOLEAN
InternalQemuFwCfgCacheSelectItem (
IN FIRMWARE_CONFIG_ITEM Item
)
{
QEMU_FW_CFG_WORK_AREA *QemuFwCfgWorkArea;
// Walk thru cached fw_items to see if Item is cached.
if (InternalQemuFwCfgItemCached (Item) == NULL) {
return FALSE;
}
QemuFwCfgWorkArea = InternalQemuFwCfgCacheGetWorkArea ();
if (QemuFwCfgWorkArea == NULL) {
DEBUG ((DEBUG_ERROR, "%a: Invalid FwCfg Cache Work Area\n", __func__));
return FALSE;
}
QemuFwCfgWorkArea->FwCfgItem = (UINT16)Item;
QemuFwCfgWorkArea->Offset = 0;
QemuFwCfgWorkArea->Reading = TRUE;
return TRUE;
}
/**
Read the fw_cfg data from Cache.
@param[in] Size Data size to be read
@param[in] Buffer Pointer to the buffer to which data is written
@retval EFI_SUCCESS - Successfully
@retval Others - As the error code indicates
**/
EFI_STATUS
InternalQemuFwCfgCacheReadBytes (
IN UINTN Size,
IN OUT VOID *Buffer
)
{
QEMU_FW_CFG_WORK_AREA *QemuFwCfgWorkArea;
FW_CFG_CACHED_ITEM *CachedItem;
UINTN ReadSize;
if (Buffer == NULL) {
return EFI_INVALID_PARAMETER;
}
QemuFwCfgWorkArea = InternalQemuFwCfgCacheGetWorkArea ();
if (QemuFwCfgWorkArea == NULL) {
return RETURN_NOT_FOUND;
}
if (!QemuFwCfgWorkArea->Reading) {
return RETURN_NOT_READY;
}
CachedItem = InternalQemuFwCfgItemCached (QemuFwCfgWorkArea->FwCfgItem);
if (CachedItem == NULL) {
return RETURN_NOT_FOUND;
}
if (QemuFwCfgWorkArea->Offset >= CachedItem->DataSize) {
DEBUG ((DEBUG_ERROR, "%a: Invalid Item Offset(0x%x) in FwCfg Cache\n", __func__, QemuFwCfgWorkArea->Offset));
ASSERT (FALSE);
return RETURN_ABORTED;
}
if (CachedItem->DataSize - QemuFwCfgWorkArea->Offset > Size) {
ReadSize = Size;
} else {
ReadSize = CachedItem->DataSize - QemuFwCfgWorkArea->Offset;
}
CopyMem (Buffer, (UINT8 *)CachedItem + sizeof (FW_CFG_CACHED_ITEM) + QemuFwCfgWorkArea->Offset, ReadSize);
QemuFwCfgWorkArea->Offset += (UINT32)ReadSize;
DEBUG ((DEBUG_VERBOSE, "%a: found Item 0x%x in FwCfg Cache\n", __func__, QemuFwCfgWorkArea->FwCfgItem));
return RETURN_SUCCESS;
}
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