[PATCH 1/3] UefiCpuPkg/PiSmmCpuDxeSmm: Introduce page table pool mechanism

["duntan" <dun.tan@intel.com>]

Introduce page table pool mechanism for smm page table to simplify
page table memory management and protection. This mechanism has been
used in DxeIpl. The basic idea is to allocate a bunch of continuous
pages of memory in advance, and all future page tables consumption
will happen in those pool instead of system memory.
Since we have centralized page tables, we only need to mark all page
table pools as RO, instead of searching page table memory layer by
layer in smm page table. Once current page table pool has been used
up, another memory pool will be allocated and the new pool will also
be set as RO if current page table memory has been marked as RO.

Signed-off-by: Dun Tan <dun.tan@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
---
 UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c           |   1 +
 UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c         |  30 ------------------------------
 UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h         |  13 +++++++++++++
 UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c | 122 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c            |   1 +
 5 files changed, 137 insertions(+), 30 deletions(-)

diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c
index 97058a2810..26efa71eff 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c
@@ -319,6 +319,7 @@ SetPageTableAttributes (
     //
     EnableCet ();
   }
+  mIsReadOnlyPageTable = TRUE;
 
   return;
 }
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c
index 37e3cfc449..655175a2c6 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c
@@ -1322,36 +1322,6 @@ ConfigSmmCodeAccessCheck (
   }
 }
 
-/**
-  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 *
-AllocatePageTableMemory (
-  IN UINTN  Pages
-  )
-{
-  VOID  *Buffer;
-
-  Buffer = SmmCpuFeaturesAllocatePageTableMemory (Pages);
-  if (Buffer != NULL) {
-    return Buffer;
-  }
-
-  return AllocatePages (Pages);
-}
-
 /**
   Allocate pages for code.
 
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
index 0bfba7e359..a0daaa1900 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
@@ -260,12 +260,25 @@ extern UINTN                 mNumberOfCpus;
 extern EFI_SMM_CPU_PROTOCOL  mSmmCpu;
 extern EFI_MM_MP_PROTOCOL    mSmmMp;
 extern BOOLEAN               m5LevelPagingNeeded;
+extern BOOLEAN               mIsReadOnlyPageTable;
 
 ///
 /// The mode of the CPU at the time an SMI occurs
 ///
 extern UINT8  mSmmSaveStateRegisterLma;
 
+#define PAGE_TABLE_POOL_ALIGNMENT   BASE_128KB
+#define PAGE_TABLE_POOL_UNIT_SIZE   BASE_128KB
+#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;
+
 //
 // SMM CPU Protocol function prototypes.
 //
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
index 773ab927e6..8f0c6410e6 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
@@ -35,6 +35,128 @@ PAGE_ATTRIBUTE_TABLE  mPageAttributeTable[] = {
 BOOLEAN  mIsShadowStack      = FALSE;
 BOOLEAN  m5LevelPagingNeeded = FALSE;
 
+//
+// Global variable to keep track current available memory used as page table.
+//
+PAGE_TABLE_POOL  *mPageTablePool = NULL;
+
+//
+// If memory used by SMM page table has been mareked as ReadOnly.
+//
+BOOLEAN  mIsReadOnlyPageTable = FALSE;
+
+/**
+  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. But usually this won't
+  happen in practice.
+
+  @param 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;
+
+  //
+  // 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);
+
+  //
+  // If page table memory has been marked as RO, mark the new pool pages as read-only.
+  //
+  if (mIsReadOnlyPageTable) {
+    AsmWriteCr0 (AsmReadCr0 () & ~CR0_WP);
+    SmmSetMemoryAttributes ((EFI_PHYSICAL_ADDRESS)(UINTN)Buffer, EFI_PAGES_TO_SIZE (PoolPages), EFI_MEMORY_RO);
+    AsmWriteCr0 (AsmReadCr0 () | CR0_WP);
+  }
+
+  return TRUE;
+}
+
+/**
+  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 *
+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;
+}
+
 /**
   Return length according to page attributes.
 
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
index bf90050503..d714ca5b5a 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
@@ -1304,6 +1304,7 @@ SetPageTableAttributes (
     //
     EnableCet ();
   }
+  mIsReadOnlyPageTable = TRUE;
 
   return;
 }
-- 
2.31.1.windows.1