mirror of
https://github.com/CloverHackyColor/CloverBootloader.git
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95 lines
2.5 KiB
C
95 lines
2.5 KiB
C
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/** @file
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OVMF support for QEMU system firmware flash device: functions specific to the
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runtime DXE driver build.
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Copyright (C) 2015, Red Hat, Inc.
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Copyright (c) 2009 - 2013, Intel Corporation. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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#include <Library/UefiRuntimeLib.h>
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#include <Library/MemEncryptSevLib.h>
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#include <Library/CcExitLib.h>
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#include <Register/Amd/Msr.h>
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#include "QemuFlash.h"
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STATIC EFI_PHYSICAL_ADDRESS mSevEsFlashPhysBase;
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VOID
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QemuFlashConvertPointers (
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VOID
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)
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{
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if (MemEncryptSevEsIsEnabled ()) {
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mSevEsFlashPhysBase = (UINTN)mFlashBase;
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}
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EfiConvertPointer (0x0, (VOID **)&mFlashBase);
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}
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VOID
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QemuFlashBeforeProbe (
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IN EFI_PHYSICAL_ADDRESS BaseAddress,
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IN UINTN FdBlockSize,
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IN UINTN FdBlockCount
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)
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{
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//
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// Do nothing
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//
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}
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/**
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Write to QEMU Flash
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@param[in] Ptr Pointer to the location to write.
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@param[in] Value The value to write.
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**/
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VOID
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QemuFlashPtrWrite (
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IN volatile UINT8 *Ptr,
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IN UINT8 Value
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)
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{
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if (MemEncryptSevEsIsEnabled ()) {
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MSR_SEV_ES_GHCB_REGISTER Msr;
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GHCB *Ghcb;
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EFI_PHYSICAL_ADDRESS PhysAddr;
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BOOLEAN InterruptState;
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Msr.GhcbPhysicalAddress = AsmReadMsr64 (MSR_SEV_ES_GHCB);
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Ghcb = Msr.Ghcb;
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//
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// The MMIO write needs to be to the physical address of the flash pointer.
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// Since this service is available as part of the EFI runtime services,
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// account for a non-identity mapped VA after SetVirtualAddressMap().
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//
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if (mSevEsFlashPhysBase == 0) {
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PhysAddr = (UINTN)Ptr;
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} else {
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PhysAddr = mSevEsFlashPhysBase + (Ptr - mFlashBase);
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}
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//
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// Writing to flash is emulated by the hypervisor through the use of write
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// protection. This won't work for an SEV-ES guest because the write won't
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// be recognized as a true MMIO write, which would result in the required
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// #VC exception. Instead, use the VMGEXIT MMIO write support directly
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// to perform the update.
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//
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CcExitVmgInit (Ghcb, &InterruptState);
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Ghcb->SharedBuffer[0] = Value;
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Ghcb->SaveArea.SwScratch = (UINT64)(UINTN)Ghcb->SharedBuffer;
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CcExitVmgSetOffsetValid (Ghcb, GhcbSwScratch);
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CcExitVmgExit (Ghcb, SVM_EXIT_MMIO_WRITE, PhysAddr, 1);
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CcExitVmgDone (Ghcb, InterruptState);
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} else {
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*Ptr = Value;
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}
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}
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