1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
|
/** @file
OVMF support for QEMU system firmware flash device: functions specific to the
runtime DXE driver build.
Copyright (C) 2015, Red Hat, Inc.
Copyright (c) 2009 - 2013, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include <Library/UefiRuntimeLib.h>
#include <Library/MemEncryptSevLib.h>
#include <Library/VmgExitLib.h>
#include <Register/Amd/Msr.h>
#include "QemuFlash.h"
STATIC EFI_PHYSICAL_ADDRESS mSevEsFlashPhysBase;
VOID
QemuFlashConvertPointers (
VOID
)
{
if (MemEncryptSevEsIsEnabled ()) {
mSevEsFlashPhysBase = (UINTN) mFlashBase;
}
EfiConvertPointer (0x0, (VOID **) &mFlashBase);
}
VOID
QemuFlashBeforeProbe (
IN EFI_PHYSICAL_ADDRESS BaseAddress,
IN UINTN FdBlockSize,
IN UINTN FdBlockCount
)
{
//
// Do nothing
//
}
/**
Write to QEMU Flash
@param[in] Ptr Pointer to the location to write.
@param[in] Value The value to write.
**/
VOID
QemuFlashPtrWrite (
IN volatile UINT8 *Ptr,
IN UINT8 Value
)
{
if (MemEncryptSevEsIsEnabled ()) {
MSR_SEV_ES_GHCB_REGISTER Msr;
GHCB *Ghcb;
EFI_PHYSICAL_ADDRESS PhysAddr;
BOOLEAN InterruptState;
Msr.GhcbPhysicalAddress = AsmReadMsr64 (MSR_SEV_ES_GHCB);
Ghcb = Msr.Ghcb;
//
// The MMIO write needs to be to the physical address of the flash pointer.
// Since this service is available as part of the EFI runtime services,
// account for a non-identity mapped VA after SetVirtualAddressMap().
//
if (mSevEsFlashPhysBase == 0) {
PhysAddr = (UINTN) Ptr;
} else {
PhysAddr = mSevEsFlashPhysBase + (Ptr - mFlashBase);
}
//
// Writing to flash is emulated by the hypervisor through the use of write
// protection. This won't work for an SEV-ES guest because the write won't
// be recognized as a true MMIO write, which would result in the required
// #VC exception. Instead, use the the VMGEXIT MMIO write support directly
// to perform the update.
//
VmgInit (Ghcb, &InterruptState);
Ghcb->SharedBuffer[0] = Value;
Ghcb->SaveArea.SwScratch = (UINT64) (UINTN) Ghcb->SharedBuffer;
VmgSetOffsetValid (Ghcb, GhcbSwScratch);
VmgExit (Ghcb, SVM_EXIT_MMIO_WRITE, PhysAddr, 1);
VmgDone (Ghcb, InterruptState);
} else {
*Ptr = Value;
}
}
|
