[PATCH v3 09/11] UefiCpuPkg/CpuDxe: Initialize stack switch for MP

[Jian J Wang <jian.j.wang@intel.com>]

> v3:
>  a. Remove definition of EXCEPTION_STACK_SWITCH_DATA.
>     Use CPU_EXCEPTION_INIT_DATA_EX defined in CpuExceptionHandlerLib.h
>     intead.
>  b. Call new API InitializeCpuExceptionHandlersEx instead to initialize
>     stack switch for BSP and AP

> v2:
>    Add code to reserve resources and initialize AP exception with stack
>    switch besides BSP, if PcdCpuStackGuard is enabled.

In current MP implementation, BSP and AP shares the same exception
configuration. Stack switch required by Stack Guard feature needs that BSP
and AP have their own configuration. This patch adds code to ask BSP and AP
to do exception handler initialization separately.

Since AP is not supposed to do memory allocation, all memory needed to
setup stack switch will be reserved in BSP and pass to AP via new API

  EFI_STATUS
  EFIAPI
  InitializeCpuExceptionHandlersEx (
    IN EFI_VECTOR_HANDOFF_INFO            *VectorInfo OPTIONAL,
    IN CPU_EXCEPTION_INIT_DATA_EX         *InitDataEx OPTIONAL
    );

Following two new PCDs are introduced to configure how to setup new stack
for specified exception handlers.

  gUefiCpuPkgTokenSpaceGuid.PcdCpuStackSwitchExceptionList
  gUefiCpuPkgTokenSpaceGuid.PcdCpuKnownGoodStackSize

Cc: Eric Dong <eric.dong@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
---
 UefiCpuPkg/CpuDxe/CpuDxe.inf |   3 +
 UefiCpuPkg/CpuDxe/CpuMp.c    | 177 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 180 insertions(+)

diff --git a/UefiCpuPkg/CpuDxe/CpuDxe.inf b/UefiCpuPkg/CpuDxe/CpuDxe.inf
index 3e8d196739..02f86b774c 100644
--- a/UefiCpuPkg/CpuDxe/CpuDxe.inf
+++ b/UefiCpuPkg/CpuDxe/CpuDxe.inf
@@ -81,6 +81,9 @@
 
 [Pcd]
   gEfiMdeModulePkgTokenSpaceGuid.PcdPteMemoryEncryptionAddressOrMask    ## CONSUMES
+  gEfiMdeModulePkgTokenSpaceGuid.PcdCpuStackGuard                       ## CONSUMES
+  gUefiCpuPkgTokenSpaceGuid.PcdCpuStackSwitchExceptionList              ## CONSUMES
+  gUefiCpuPkgTokenSpaceGuid.PcdCpuKnownGoodStackSize                    ## CONSUMES
 
 [Depex]
   TRUE
diff --git a/UefiCpuPkg/CpuDxe/CpuMp.c b/UefiCpuPkg/CpuDxe/CpuMp.c
index b3c0178d07..2e388879fa 100644
--- a/UefiCpuPkg/CpuDxe/CpuMp.c
+++ b/UefiCpuPkg/CpuDxe/CpuMp.c
@@ -601,6 +601,178 @@ CollectBistDataFromHob (
   }
 }
 
+/**
+  Get GDT register value.
+
+  This function is mainly for AP purpose because AP may have different GDT
+  table than BSP.
+
+  @param[in,out] Buffer  The pointer to private data buffer.
+
+**/
+VOID
+EFIAPI
+GetGdtr (
+  IN OUT VOID *Buffer
+  )
+{
+  AsmReadGdtr ((IA32_DESCRIPTOR *)Buffer);
+}
+
+/**
+  Initializes CPU exceptions handlers for the sake of stack switch requirement.
+
+  This function is a wrapper of InitializeCpuExceptionHandlersEx. It's mainly
+  for the sake of AP's init because of EFI_AP_PROCEDURE API requirement.
+
+  @param[in,out] Buffer  The pointer to private data buffer.
+
+**/
+VOID
+EFIAPI
+InitializeExceptionStackSwitchHandlers (
+  IN OUT VOID *Buffer
+  )
+{
+  CPU_EXCEPTION_INIT_DATA_EX        *EssData;
+  IA32_DESCRIPTOR                   Idtr;
+  EFI_STATUS                        Status;
+
+  EssData = Buffer;
+  //
+  // We don't plan to replace IDT table with a new one, and we should not assume
+  // the AP's IDT is the same as BSP's IDT either.
+  //
+  AsmReadIdtr (&Idtr);
+  EssData->Ia32.IdtTable = (VOID *)Idtr.Base;
+  Status = InitializeCpuExceptionHandlersEx (NULL, EssData);
+  ASSERT_EFI_ERROR (Status);
+}
+
+/**
+  Initializes MP exceptions handlers for the sake of stack switch requirement.
+
+  This function will allocate required resources required to setup stack switch
+  and pass them through CPU_EXCEPTION_INIT_DATA_EX to each logic processor.
+
+**/
+VOID
+InitializeMpExceptionStackSwitchHandlers (
+  VOID
+  )
+{
+  UINTN                           Index;
+  UINTN                           Bsp;
+  UINTN                           ExceptionNumber;
+  UINTN                           NewGdtSize;
+  UINTN                           NewStackSize;
+  IA32_DESCRIPTOR                 Gdtr;
+  CPU_EXCEPTION_INIT_DATA_EX      EssData;
+  UINT8                           *GdtBuffer;
+  UINT8                           *StackTop;
+
+  if (!PcdGetBool (PcdCpuStackGuard)) {
+    return;
+  }
+
+  ExceptionNumber = FixedPcdGetSize (PcdCpuStackSwitchExceptionList);
+  NewStackSize = FixedPcdGet32 (PcdCpuKnownGoodStackSize) * ExceptionNumber;
+
+  StackTop = AllocateRuntimeZeroPool (NewStackSize * mNumberOfProcessors);
+  ASSERT (StackTop != NULL);
+  StackTop += NewStackSize  * mNumberOfProcessors;
+
+  //
+  // The default exception handlers must have been initialized. Let's just skip
+  // it in this method.
+  //
+  EssData.Ia32.InitDefaultHandlers = FALSE;
+
+  EssData.Ia32.StackSwitchExceptions = FixedPcdGetPtr(PcdCpuStackSwitchExceptionList);
+  EssData.Ia32.StackSwitchExceptionNumber = ExceptionNumber;
+  EssData.Ia32.KnownGoodStackSize = FixedPcdGet32(PcdCpuKnownGoodStackSize);
+
+  MpInitLibWhoAmI (&Bsp);
+  for (Index = 0; Index < mNumberOfProcessors; ++Index) {
+    //
+    // To support stack switch, we need to re-construct GDT but not IDT.
+    //
+    if (Index == Bsp) {
+      GetGdtr (&Gdtr);
+    } else {
+      //
+      // AP might have different size of GDT from BSP.
+      //
+      MpInitLibStartupThisAP (GetGdtr, Index, NULL, 0, (VOID *)&Gdtr, NULL);
+    }
+
+    //
+    // X64 needs only one TSS of current task working for all exceptions
+    // because of its IST feature. IA32 needs one TSS for each exception
+    // in addition to current task. Since AP is not supposed to allocate
+    // memory, we have to do it in BSP. To simplify the code, we allocate
+    // memory for IA32 case to cover both IA32 and X64 exception stack
+    // switch.
+    //
+    // Layout of memory to allocate for each processor:
+    //    --------------------------------
+    //    |            Alignment         |  (just in case)
+    //    --------------------------------
+    //    |                              |
+    //    |        Original GDT          |
+    //    |                              |
+    //    --------------------------------
+    //    |    Current task descriptor   |
+    //    --------------------------------
+    //    |                              |
+    //    |  Exception task descriptors  |  X ExceptionNumber
+    //    |                              |
+    //    --------------------------------
+    //    |  Current task-state segment  |
+    //    --------------------------------
+    //    |                              |
+    //    | Exception task-state segment |  X ExceptionNumber
+    //    |                              |
+    //    --------------------------------
+    //
+    NewGdtSize = sizeof (IA32_TSS_DESCRIPTOR) +
+                 (Gdtr.Limit + 1) +
+                 sizeof (IA32_TSS_DESCRIPTOR) * (ExceptionNumber + 1) +
+                 sizeof (IA32_TASK_STATE_SEGMENT) * (ExceptionNumber + 1);
+    GdtBuffer = AllocateRuntimeZeroPool (NewGdtSize);
+    ASSERT (GdtBuffer != NULL);
+
+    EssData.Ia32.GdtTable = ALIGN_POINTER(GdtBuffer, sizeof (IA32_TSS_DESCRIPTOR));
+    NewGdtSize -= ((UINT8 *)EssData.Ia32.GdtTable - GdtBuffer);
+    EssData.Ia32.GdtSize = NewGdtSize;
+
+    EssData.Ia32.TssDesc = ((UINT8 *)EssData.Ia32.GdtTable + Gdtr.Limit + 1);
+    EssData.Ia32.Tss = ((UINT8 *)EssData.Ia32.GdtTable + Gdtr.Limit + 1 +
+                        sizeof (IA32_TSS_DESCRIPTOR) * (ExceptionNumber + 1));
+
+    EssData.Ia32.KnownGoodStackTop = (UINTN)StackTop;
+    DEBUG ((DEBUG_INFO,
+            "Exception stack top[cpu%lu]: 0x%lX\n",
+            (UINT64)(UINTN)Index,
+            (UINT64)(UINTN)StackTop));
+
+    if (Index == Bsp) {
+      InitializeExceptionStackSwitchHandlers (&EssData);
+    } else {
+      MpInitLibStartupThisAP (
+        InitializeExceptionStackSwitchHandlers,
+        Index,
+        NULL,
+        0,
+        (VOID *)&EssData,
+        NULL
+        );
+    }
+
+    StackTop  -= NewStackSize;
+  }
+}
+
 /**
   Initialize Multi-processor support.
 
@@ -624,6 +796,11 @@ InitializeMpSupport (
   mNumberOfProcessors = NumberOfProcessors;
   DEBUG ((DEBUG_INFO, "Detect CPU count: %d\n", mNumberOfProcessors));
 
+  //
+  // Initialize exception stack switch handlers for each logic processor.
+  //
+  InitializeMpExceptionStackSwitchHandlers ();
+
   //
   // Update CPU healthy information from Guided HOB
   //
-- 
2.14.1.windows.1