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UefiCpuPkg/CpuDxe: Enable protection for newly added page table 

One of the functionalities of CpuDxe is to update memory paging attributes.
If page table protection is applied, it must be disabled temporarily before
any attributes update and enabled again afterwards.

This patch makes use of the same way as DxeIpl to allocate page table memory
from reserved memory pool, which helps to reduce potential "split" operation
and recursive calling of SetMemorySpaceAttributes().

Laszlo (lersek@redhat.com) did a regression test on QEMU virtual platform with
one middle version of this series patch. The details can be found at

 https://lists.01.org/pipermail/edk2-devel/2017-December/018625.html

There're a few changes after his work.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
This commit is contained in:
Jian J Wang 2017-12-12 09:16:35 +08:00 committed by Star Zeng
parent 2ac1730bf2
commit 147fd35c3e
4 changed files with 267 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
UefiCpuPkg/CpuDxe/CpuDxe.c
View File

@ -25,6 +25,7 @@
BOOLEAN InterruptState = FALSE;
EFI_HANDLE mCpuHandle = NULL;
BOOLEAN mIsFlushingGCD;
BOOLEAN mIsAllocatingPageTable = FALSE;
UINT64 mValidMtrrAddressMask;
UINT64 mValidMtrrBitsMask;
UINT64 mTimerPeriod = 0;
@ -407,6 +408,20 @@ CpuSetMemoryAttributes (
return EFI_SUCCESS;
}
//
// During memory attributes updating, new pages may be allocated to setup
// smaller granularity of page table. Page allocation action might then cause
// another calling of CpuSetMemoryAttributes() recursively, due to memory
// protection policy configured (such as PcdDxeNxMemoryProtectionPolicy).
// Since this driver will always protect memory used as page table by itself,
// there's no need to apply protection policy requested from memory service.
// So it's safe to just return EFI_SUCCESS if this time of calling is caused
// by page table memory allocation.
//
if (mIsAllocatingPageTable) {
DEBUG((DEBUG_VERBOSE, " Allocating page table memory\n"));
return EFI_SUCCESS;
}
CacheAttributes = Attributes & CACHE_ATTRIBUTE_MASK;
MemoryAttributes = Attributes & MEMORY_ATTRIBUTE_MASK;
@ -487,7 +502,7 @@ CpuSetMemoryAttributes (
//
// Set memory attribute by page table
//
return AssignMemoryPageAttributes (NULL, BaseAddress, Length, MemoryAttributes, AllocatePages);
return AssignMemoryPageAttributes (NULL, BaseAddress, Length, MemoryAttributes, NULL);
}
/**

2
UefiCpuPkg/CpuDxe/CpuDxe.h
View File

@ -273,5 +273,7 @@ RefreshGcdMemoryAttributesFromPaging (
VOID
);
extern BOOLEAN mIsAllocatingPageTable;
#endif

223
UefiCpuPkg/CpuDxe/CpuPageTable.c
View File

@ -87,6 +87,8 @@ PAGE_ATTRIBUTE_TABLE mPageAttributeTable[] = {
{Page1G, SIZE_1GB, PAGING_1G_ADDRESS_MASK_64},
};
PAGE_TABLE_POOL *mPageTablePool = NULL;
/**
Enable write protection function for AP.
@ -172,10 +174,6 @@ GetCurrentPagingContext (
}
if ((AsmReadCr0 () & BIT31) != 0) {
PagingContext->ContextData.X64.PageTableBase = (AsmReadCr3 () & PAGING_4K_ADDRESS_MASK_64);
if ((AsmReadCr0 () & BIT16) == 0) {
AsmWriteCr0 (AsmReadCr0 () | BIT16);
SyncMemoryPageAttributesAp (SyncCpuEnableWriteProtection);
}
} else {
PagingContext->ContextData.X64.PageTableBase = 0;
}
@ -561,6 +559,59 @@ SplitPage (
}
}
/**
Check the WP status in CR0 register. This bit is used to lock or unlock write
access to pages marked as read-only.
@retval TRUE Write protection is enabled.
@retval FALSE Write protection is disabled.
**/
BOOLEAN
IsReadOnlyPageWriteProtected (
VOID
)
{
return ((AsmReadCr0 () & BIT16) != 0);
}
/**
Disable write protection function for AP.
@param[in,out] Buffer The pointer to private data buffer.
**/
VOID
EFIAPI
SyncCpuDisableWriteProtection (
IN OUT VOID *Buffer
)
{
AsmWriteCr0 (AsmReadCr0() & ~BIT16);
}
/**
Disable Write Protect on pages marked as read-only.
**/
VOID
DisableReadOnlyPageWriteProtect (
VOID
)
{
AsmWriteCr0 (AsmReadCr0() & ~BIT16);
SyncMemoryPageAttributesAp (SyncCpuDisableWriteProtection);
}
/**
Enable Write Protect on pages marked as read-only.
**/
VOID
EnableReadOnlyPageWriteProtect (
VOID
)
{
AsmWriteCr0 (AsmReadCr0() | BIT16);
SyncMemoryPageAttributesAp (SyncCpuEnableWriteProtection);
}
/**
This function modifies the page attributes for the memory region specified by BaseAddress and
Length from their current attributes to the attributes specified by Attributes.
@ -609,6 +660,7 @@ ConvertMemoryPageAttributes (
PAGE_ATTRIBUTE SplitAttribute;
RETURN_STATUS Status;
BOOLEAN IsEntryModified;
BOOLEAN IsWpEnabled;
if ((BaseAddress & (SIZE_4KB - 1)) != 0) {
DEBUG ((DEBUG_ERROR, "BaseAddress(0x%lx) is not aligned!\n", BaseAddress));
@ -665,14 +717,27 @@ ConvertMemoryPageAttributes (
if (IsModified != NULL) {
*IsModified = FALSE;
}
if (AllocatePagesFunc == NULL) {
AllocatePagesFunc = AllocatePageTableMemory;
}
//
// Make sure that the page table is changeable.
//
IsWpEnabled = IsReadOnlyPageWriteProtected ();
if (IsWpEnabled) {
DisableReadOnlyPageWriteProtect ();
}
//
// Below logic is to check 2M/4K page to make sure we donot waist memory.
//
Status = EFI_SUCCESS;
while (Length != 0) {
PageEntry = GetPageTableEntry (&CurrentPagingContext, BaseAddress, &PageAttribute);
if (PageEntry == NULL) {
return RETURN_UNSUPPORTED;
Status = RETURN_UNSUPPORTED;
goto Done;
}
PageEntryLength = PageAttributeToLength (PageAttribute);
SplitAttribute = NeedSplitPage (BaseAddress, Length, PageEntry, PageAttribute);
@ -690,11 +755,13 @@ ConvertMemoryPageAttributes (
Length -= PageEntryLength;
} else {
if (AllocatePagesFunc == NULL) {
return RETURN_UNSUPPORTED;
Status = RETURN_UNSUPPORTED;
goto Done;
}
Status = SplitPage (PageEntry, PageAttribute, SplitAttribute, AllocatePagesFunc);
if (RETURN_ERROR (Status)) {
return RETURN_UNSUPPORTED;
Status = RETURN_UNSUPPORTED;
goto Done;
}
if (IsSplitted != NULL) {
*IsSplitted = TRUE;
@ -709,7 +776,14 @@ ConvertMemoryPageAttributes (
}
}
return RETURN_SUCCESS;
Done:
//
// Restore page table write protection, if any.
//
if (IsWpEnabled) {
EnableReadOnlyPageWriteProtect ();
}
return Status;
}
/**
@ -922,6 +996,127 @@ RefreshGcdMemoryAttributesFromPaging (
FreePool (MemorySpaceMap);
}
/**
Initialize a buffer pool for page table use only.
To reduce the potential split operation on page table, the pages reserved for
page table should be allocated in the times of PAGE_TABLE_POOL_UNIT_PAGES and
at the boundary of PAGE_TABLE_POOL_ALIGNMENT. So the page pool is always
initialized with number of pages greater than or equal to the given PoolPages.
Once the pages in the pool are used up, this method should be called again to
reserve at least another PAGE_TABLE_POOL_UNIT_PAGES. Usually this won't happen
often in practice.
@param[in] PoolPages The least page number of the pool to be created.
@retval TRUE The pool is initialized successfully.
@retval FALSE The memory is out of resource.
**/
BOOLEAN
InitializePageTablePool (
IN UINTN PoolPages
)
{
VOID *Buffer;
BOOLEAN IsModified;
//
// Always reserve at least PAGE_TABLE_POOL_UNIT_PAGES, including one page for
// header.
//
PoolPages += 1; // Add one page for header.
PoolPages = ((PoolPages - 1) / PAGE_TABLE_POOL_UNIT_PAGES + 1) *
PAGE_TABLE_POOL_UNIT_PAGES;
Buffer = AllocateAlignedPages (PoolPages, PAGE_TABLE_POOL_ALIGNMENT);
if (Buffer == NULL) {
DEBUG ((DEBUG_ERROR, "ERROR: Out of aligned pages\r\n"));
return FALSE;
}
//
// Link all pools into a list for easier track later.
//
if (mPageTablePool == NULL) {
mPageTablePool = Buffer;
mPageTablePool->NextPool = mPageTablePool;
} else {
((PAGE_TABLE_POOL *)Buffer)->NextPool = mPageTablePool->NextPool;
mPageTablePool->NextPool = Buffer;
mPageTablePool = Buffer;
}
//
// Reserve one page for pool header.
//
mPageTablePool->FreePages = PoolPages - 1;
mPageTablePool->Offset = EFI_PAGES_TO_SIZE (1);
//
// Mark the whole pool pages as read-only.
//
ConvertMemoryPageAttributes (
NULL,
(PHYSICAL_ADDRESS)(UINTN)Buffer,
EFI_PAGES_TO_SIZE (PoolPages),
EFI_MEMORY_RO,
PageActionSet,
AllocatePageTableMemory,
NULL,
&IsModified
);
ASSERT (IsModified == TRUE);
return TRUE;
}
/**
This API provides a way to allocate memory for page table.
This API can be called more than once to allocate memory for page tables.
Allocates the number of 4KB pages and returns a pointer to the allocated
buffer. The buffer returned is aligned on a 4KB boundary.
If Pages is 0, then NULL is returned.
If there is not enough memory remaining to satisfy the request, then NULL is
returned.
@param Pages The number of 4 KB pages to allocate.
@return A pointer to the allocated buffer or NULL if allocation fails.
**/
VOID *
EFIAPI
AllocatePageTableMemory (
IN UINTN Pages
)
{
VOID *Buffer;
if (Pages == 0) {
return NULL;
}
//
// Renew the pool if necessary.
//
if (mPageTablePool == NULL ||
Pages > mPageTablePool->FreePages) {
if (!InitializePageTablePool (Pages)) {
return NULL;
}
}
Buffer = (UINT8 *)mPageTablePool + mPageTablePool->Offset;
mPageTablePool->Offset += EFI_PAGES_TO_SIZE (Pages);
mPageTablePool->FreePages -= Pages;
return Buffer;
}
/**
Initialize the Page Table lib.
**/
@ -933,6 +1128,18 @@ InitializePageTableLib (
PAGE_TABLE_LIB_PAGING_CONTEXT CurrentPagingContext;
GetCurrentPagingContext (&CurrentPagingContext);
//
// Reserve memory of page tables for future uses, if paging is enabled.
//
if (CurrentPagingContext.ContextData.X64.PageTableBase != 0 &&
(CurrentPagingContext.ContextData.Ia32.Attributes &
PAGE_TABLE_LIB_PAGING_CONTEXT_IA32_X64_ATTRIBUTES_PAE) != 0) {
DisableReadOnlyPageWriteProtect ();
InitializePageTablePool (1);
EnableReadOnlyPageWriteProtect ();
}
DEBUG ((DEBUG_INFO, "CurrentPagingContext:\n", CurrentPagingContext.MachineType));
DEBUG ((DEBUG_INFO, " MachineType - 0x%x\n", CurrentPagingContext.MachineType));
DEBUG ((DEBUG_INFO, " PageTableBase - 0x%x\n", CurrentPagingContext.ContextData.X64.PageTableBase));

34
UefiCpuPkg/CpuDxe/CpuPageTable.h
View File

@ -50,6 +50,19 @@ typedef struct {
PAGE_TABLE_LIB_PAGING_CONTEXT_DATA ContextData;
} PAGE_TABLE_LIB_PAGING_CONTEXT;
#define PAGE_TABLE_POOL_ALIGNMENT BASE_2MB
#define PAGE_TABLE_POOL_UNIT_SIZE SIZE_2MB
#define PAGE_TABLE_POOL_UNIT_PAGES EFI_SIZE_TO_PAGES (PAGE_TABLE_POOL_UNIT_SIZE)
#define PAGE_TABLE_POOL_ALIGN_MASK \
(~(EFI_PHYSICAL_ADDRESS)(PAGE_TABLE_POOL_ALIGNMENT - 1))
typedef struct {
VOID *NextPool;
UINTN Offset;
UINTN FreePages;
} PAGE_TABLE_POOL;
/**
Allocates one or more 4KB pages for page table.
@ -110,4 +123,25 @@ InitializePageTableLib (
VOID
);
/**
This API provides a way to allocate memory for page table.
This API can be called more once to allocate memory for page tables.
Allocates the number of 4KB pages of type EfiRuntimeServicesData and returns a pointer to the
allocated buffer. The buffer returned is aligned on a 4KB boundary. If Pages is 0, then NULL
is returned. If there is not enough memory remaining to satisfy the request, then NULL is
returned.
@param Pages The number of 4 KB pages to allocate.
@return A pointer to the allocated buffer or NULL if allocation fails.
**/
VOID *
EFIAPI
AllocatePageTableMemory (
IN UINTN Pages
);
#endif