audk/OvmfPkg/PlatformPei/MemDetect.c

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/**@file
Memory Detection for Virtual Machines.
Copyright (c) 2006 - 2014, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
Module Name:
MemDetect.c
**/
//
// The package level header files this module uses
//
#include <PiPei.h>
//
// The Library classes this module consumes
//
#include <Library/BaseMemoryLib.h>
#include <Library/DebugLib.h>
#include <Library/HobLib.h>
#include <Library/IoLib.h>
#include <Library/PcdLib.h>
#include <Library/PeimEntryPoint.h>
#include <Library/ResourcePublicationLib.h>
#include <Library/MtrrLib.h>
#include "Platform.h"
#include "Cmos.h"
UINT32
GetSystemMemorySizeBelow4gb (
VOID
)
{
UINT8 Cmos0x34;
UINT8 Cmos0x35;
//
// CMOS 0x34/0x35 specifies the system memory above 16 MB.
// * CMOS(0x35) is the high byte
// * CMOS(0x34) is the low byte
// * The size is specified in 64kb chunks
// * Since this is memory above 16MB, the 16MB must be added
// into the calculation to get the total memory size.
//
Cmos0x34 = (UINT8) CmosRead8 (0x34);
Cmos0x35 = (UINT8) CmosRead8 (0x35);
return (((UINTN)((Cmos0x35 << 8) + Cmos0x34) << 16) + SIZE_16MB);
}
STATIC
UINT64
GetSystemMemorySizeAbove4gb (
)
{
UINT32 Size;
UINTN CmosIndex;
//
// CMOS 0x5b-0x5d specifies the system memory above 4GB MB.
// * CMOS(0x5d) is the most significant size byte
// * CMOS(0x5c) is the middle size byte
// * CMOS(0x5b) is the least significant size byte
// * The size is specified in 64kb chunks
//
Size = 0;
for (CmosIndex = 0x5d; CmosIndex >= 0x5b; CmosIndex--) {
Size = (UINT32) (Size << 8) + (UINT32) CmosRead8 (CmosIndex);
}
return LShiftU64 (Size, 16);
}
/**
Publish PEI core memory
@return EFI_SUCCESS The PEIM initialized successfully.
**/
EFI_STATUS
PublishPeiMemory (
VOID
)
{
EFI_STATUS Status;
EFI_PHYSICAL_ADDRESS MemoryBase;
UINT64 MemorySize;
UINT64 LowerMemorySize;
if (mBootMode == BOOT_ON_S3_RESUME) {
MemoryBase = PcdGet32 (PcdS3AcpiReservedMemoryBase);
MemorySize = PcdGet32 (PcdS3AcpiReservedMemorySize);
} else {
LowerMemorySize = GetSystemMemorySizeBelow4gb ();
//
// Determine the range of memory to use during PEI
//
MemoryBase = PcdGet32 (PcdOvmfDxeMemFvBase) + PcdGet32 (PcdOvmfDxeMemFvSize);
MemorySize = LowerMemorySize - MemoryBase;
if (MemorySize > SIZE_64MB) {
MemoryBase = LowerMemorySize - SIZE_64MB;
MemorySize = SIZE_64MB;
}
}
//
// Publish this memory to the PEI Core
//
Status = PublishSystemMemory(MemoryBase, MemorySize);
ASSERT_EFI_ERROR (Status);
return Status;
}
/**
Peform Memory Detection for QEMU / KVM
**/
STATIC
VOID
QemuInitializeRam (
VOID
)
{
UINT64 LowerMemorySize;
UINT64 UpperMemorySize;
DEBUG ((EFI_D_INFO, "%a called\n", __FUNCTION__));
//
// Determine total memory size available
//
LowerMemorySize = GetSystemMemorySizeBelow4gb ();
UpperMemorySize = GetSystemMemorySizeAbove4gb ();
if (mBootMode != BOOT_ON_S3_RESUME) {
//
// Create memory HOBs
//
AddMemoryRangeHob (BASE_1MB, LowerMemorySize);
AddMemoryRangeHob (0, BASE_512KB + BASE_128KB);
}
MtrrSetMemoryAttribute (BASE_1MB, LowerMemorySize - BASE_1MB, CacheWriteBack);
MtrrSetMemoryAttribute (0, BASE_512KB + BASE_128KB, CacheWriteBack);
if (UpperMemorySize != 0) {
if (mBootMode != BOOT_ON_S3_RESUME) {
AddUntestedMemoryBaseSizeHob (BASE_4GB, UpperMemorySize);
}
MtrrSetMemoryAttribute (BASE_4GB, UpperMemorySize, CacheWriteBack);
}
}
/**
Publish system RAM and reserve memory regions
**/
VOID
InitializeRamRegions (
VOID
)
{
if (!mXen) {
QemuInitializeRam ();
} else {
XenPublishRamRegions ();
}
if (mS3Supported && mBootMode != BOOT_ON_S3_RESUME) {
//
// This is the memory range that will be used for PEI on S3 resume
//
BuildMemoryAllocationHob (
(EFI_PHYSICAL_ADDRESS)(UINTN) PcdGet32 (PcdS3AcpiReservedMemoryBase),
(UINT64)(UINTN) PcdGet32 (PcdS3AcpiReservedMemorySize),
EfiACPIMemoryNVS
);
//
// Cover the initial RAM area used as stack and temporary PEI heap.
//
// This is reserved as ACPI NVS so it can be used on S3 resume.
//
BuildMemoryAllocationHob (
PcdGet32 (PcdOvmfSecPeiTempRamBase),
PcdGet32 (PcdOvmfSecPeiTempRamSize),
EfiACPIMemoryNVS
);
OvmfPkg: PlatformPei: protect SEC's GUIDed section handler table thru S3 OVMF's SecMain is unique in the sense that it links against the following two libraries *in combination*: - IntelFrameworkModulePkg/Library/LzmaCustomDecompressLib/ LzmaCustomDecompressLib.inf - MdePkg/Library/BaseExtractGuidedSectionLib/ BaseExtractGuidedSectionLib.inf The ExtractGuidedSectionLib library class allows decompressor modules to register themselves (keyed by GUID) with it, and it allows clients to decompress file sections with a registered decompressor module that matches the section's GUID. BaseExtractGuidedSectionLib is a library instance (of type BASE) for this library class. It has no constructor function. LzmaCustomDecompressLib is a compatible decompressor module (of type BASE). Its section type GUID is gLzmaCustomDecompressGuid == EE4E5898-3914-4259-9D6E-DC7BD79403CF When OVMF's SecMain module starts, the LzmaCustomDecompressLib constructor function is executed, which registers its LZMA decompressor with the above GUID, by calling into BaseExtractGuidedSectionLib: LzmaDecompressLibConstructor() [GuidedSectionExtraction.c] ExtractGuidedSectionRegisterHandlers() [BaseExtractGuidedSectionLib.c] GetExtractGuidedSectionHandlerInfo() PcdGet64 (PcdGuidedExtractHandlerTableAddress) -- NOTE THIS Later, during a normal (non-S3) boot, SecMain utilizes this decompressor to get information about, and to decompress, sections of the OVMF firmware image: SecCoreStartupWithStack() [OvmfPkg/Sec/SecMain.c] SecStartupPhase2() FindAndReportEntryPoints() FindPeiCoreImageBase() DecompressMemFvs() ExtractGuidedSectionGetInfo() [BaseExtractGuidedSectionLib.c] ExtractGuidedSectionDecode() [BaseExtractGuidedSectionLib.c] Notably, only the extraction depends on full-config-boot; the registration of LzmaCustomDecompressLib occurs unconditionally in the SecMain EFI binary, triggered by the library constructor function. This is where the bug happens. BaseExtractGuidedSectionLib maintains the table of GUIDed decompressors (section handlers) at a fixed memory location; selected by PcdGuidedExtractHandlerTableAddress (declared in MdePkg.dec). The default value of this PCD is 0x1000000 (16 MB). This causes SecMain to corrupt guest OS memory during S3, leading to random crashes. Compare the following two memory dumps, the first taken right before suspending, the second taken right after resuming a RHEL-7 guest: crash> rd -8 -p 1000000 0x50 1000000: c0 00 08 00 02 00 00 00 00 00 00 00 00 00 00 00 ................ 1000010: d0 33 0c 00 00 c9 ff ff c0 10 00 01 00 88 ff ff .3.............. 1000020: 0a 6d 57 32 0f 00 00 00 38 00 00 01 00 88 ff ff .mW2....8....... 1000030: 00 00 00 00 00 00 00 00 73 69 67 6e 61 6c 6d 6f ........signalmo 1000040: 64 75 6c 65 2e 73 6f 00 00 00 00 00 00 00 00 00 dule.so......... vs. crash> rd -8 -p 1000000 0x50 1000000: 45 47 53 49 01 00 00 00 20 00 00 01 00 00 00 00 EGSI.... ....... 1000010: 20 01 00 01 00 00 00 00 a0 01 00 01 00 00 00 00 ............... 1000020: 98 58 4e ee 14 39 59 42 9d 6e dc 7b d7 94 03 cf .XN..9YB.n.{.... 1000030: 00 00 00 00 00 00 00 00 73 69 67 6e 61 6c 6d 6f ........signalmo 1000040: 64 75 6c 65 2e 73 6f 00 00 00 00 00 00 00 00 00 dule.so......... The "EGSI" signature corresponds to EXTRACT_HANDLER_INFO_SIGNATURE declared in MdePkg/Library/BaseExtractGuidedSectionLib/BaseExtractGuidedSectionLib.c. Additionally, the gLzmaCustomDecompressGuid (quoted above) is visible at guest-phys offset 0x1000020. Fix the problem as follows: - Carve out 4KB from the 36KB gap that we currently have between PcdOvmfLockBoxStorageBase + PcdOvmfLockBoxStorageSize == 8220 KB and PcdOvmfSecPeiTempRamBase == 8256 KB. - Point PcdGuidedExtractHandlerTableAddress to 8220 KB (0x00807000). - Cover the area with an EfiACPIMemoryNVS type memalloc HOB, if S3 is supported and we're not currently resuming. The 4KB size that we pick is an upper estimate for BaseExtractGuidedSectionLib's internal storage size. The latter is calculated as follows (see GetExtractGuidedSectionHandlerInfo()): sizeof(EXTRACT_GUIDED_SECTION_HANDLER_INFO) + // 32 PcdMaximumGuidedExtractHandler * ( sizeof(GUID) + // 16 sizeof(EXTRACT_GUIDED_SECTION_DECODE_HANDLER) + // 8 sizeof(EXTRACT_GUIDED_SECTION_GET_INFO_HANDLER) // 8 ) OVMF sets PcdMaximumGuidedExtractHandler to 16 decimal (which is the MdePkg default too), yielding 32 + 16 * (16 + 8 + 8) == 544 bytes. Regarding the lifecycle of the new area: (a) when and how it is initialized after first boot of the VM The library linked into SecMain finds that the area lacks the signature. It initializes the signature, plus the rest of the structure. This is independent of S3 support. Consumption of the area is also limited to SEC (but consumption does depend on full-config-boot). (b) how it is protected from memory allocations during DXE It is not, in the general case; and we don't need to. Nothing else links against BaseExtractGuidedSectionLib; it's OK if DXE overwrites the area. (c) how it is protected from the OS When S3 is enabled, we cover it with AcpiNVS in InitializeRamRegions(). When S3 is not supported, the range is not protected. (d) how it is accessed on the S3 resume path Examined by the library linked into SecMain. Registrations update the table in-place (based on GUID matches). (e) how it is accessed on the warm reset path If S3 is enabled, then the OS won't damage the table (due to (c)), hence see (d). If S3 is unsupported, then the OS may or may not overwrite the signature. (It likely will.) This is identical to the pre-patch status. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Jordan Justen <jordan.l.justen@intel.com> git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15433 6f19259b-4bc3-4df7-8a09-765794883524
2014-04-05 23:26:09 +02:00
//
// SEC stores its table of GUIDed section handlers here.
//
BuildMemoryAllocationHob (
PcdGet64 (PcdGuidedExtractHandlerTableAddress),
PcdGet32 (PcdGuidedExtractHandlerTableSize),
EfiACPIMemoryNVS
);
#ifdef MDE_CPU_X64
//
// Reserve the initial page tables built by the reset vector code.
//
// Since this memory range will be used by the Reset Vector on S3
// resume, it must be reserved as ACPI NVS.
//
BuildMemoryAllocationHob (
(EFI_PHYSICAL_ADDRESS)(UINTN) PcdGet32 (PcdOvmfSecPageTablesBase),
(UINT64)(UINTN) PcdGet32 (PcdOvmfSecPageTablesSize),
EfiACPIMemoryNVS
);
#endif
}
if (mBootMode != BOOT_ON_S3_RESUME) {
//
// Reserve the lock box storage area
//
// Since this memory range will be used on S3 resume, it must be
// reserved as ACPI NVS.
//
// If S3 is unsupported, then various drivers might still write to the
// LockBox area. We ought to prevent DXE from serving allocation requests
// such that they would overlap the LockBox storage.
//
ZeroMem (
(VOID*)(UINTN) PcdGet32 (PcdOvmfLockBoxStorageBase),
(UINTN) PcdGet32 (PcdOvmfLockBoxStorageSize)
);
BuildMemoryAllocationHob (
(EFI_PHYSICAL_ADDRESS)(UINTN) PcdGet32 (PcdOvmfLockBoxStorageBase),
(UINT64)(UINTN) PcdGet32 (PcdOvmfLockBoxStorageSize),
mS3Supported ? EfiACPIMemoryNVS : EfiBootServicesData
);
}
}