Re: [PATCH v2 1/3] UefiCpuPkg/PiSmmCpuDxeSmm: handle dynamic PcdCpuMaxLogicalProcessorNumber

["Fan, Jeff" <jeff.fan@intel.com>]

Laszlo,

Even getting PcdCpuMaxLogicalProcessorNumber is legal in InitSmmProfileInternal() that is only invoked on boot time, I agree to do this updating in this patch.
We need to try to use mMaxNumberOfCpus as possible for size saving and performance improvement.

Reviewed-by: Jeff Fan <jeff.fan@intel.com>

Jeff

-----Original Message-----
From: Laszlo Ersek [mailto:lersek@redhat.com] 
Sent: Friday, November 25, 2016 4:57 AM
To: edk2-devel-01
Cc: Igor Mammedov; Fan, Jeff; Justen, Jordan L; Kinney, Michael D
Subject: [PATCH v2 1/3] UefiCpuPkg/PiSmmCpuDxeSmm: handle dynamic PcdCpuMaxLogicalProcessorNumber

"UefiCpuPkg/UefiCpuPkg.dec" already allows platforms to make PcdCpuMaxLogicalProcessorNumber dynamic, however PiSmmCpuDxeSmm does not take this into account everywhere. As soon as a platform turns the PCD into a dynamic one, at least S3 fails. When the PCD is dynamic, all
PcdGet() calls translate into PCD DXE protocol calls, which are only permitted at boot time, not at runtime or during S3 resume.

We already have a variable called mMaxNumberOfCpus; it is initialized in the entry point function like this:

> //
> // If support CPU hot plug, we need to allocate resources for possibly 
> // hot-added processors // if (FeaturePcdGet (PcdCpuHotPlugSupport)) {
>   mMaxNumberOfCpus = PcdGet32 (PcdCpuMaxLogicalProcessorNumber);
> } else {
>   mMaxNumberOfCpus = mNumberOfCpus;
> }

There's another use of the PCD a bit higher up, also in the entry point
function:

> //
> // Use MP Services Protocol to retrieve the number of processors and 
> // number of enabled processors // Status = 
> MpServices->GetNumberOfProcessors (MpServices, &mNumberOfCpus,
>                        &NumberOfEnabledProcessors); ASSERT_EFI_ERROR 
> (Status); ASSERT (mNumberOfCpus <= PcdGet32 
> (PcdCpuMaxLogicalProcessorNumber));

Preserve these calls in the entry point function, and replace all other uses of PcdCpuMaxLogicalProcessorNumber -- there are only reads -- with mMaxNumberOfCpus.

For PcdCpuHotPlugSupport==TRUE, this is an unobservable change.

For PcdCpuHotPlugSupport==FALSE, we even save SMRAM, because we no longer allocate resources needlessly for CPUs that can never appear in the system.

PcdCpuMaxLogicalProcessorNumber is also retrieved in "UefiCpuPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c",  but only in the library instance constructor, which runs even before the entry point function is called.

Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jeff Fan <jeff.fan@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Bugzilla: https://bugzilla.tianocore.org/show_bug.cgi?id=116
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
---
 UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c |  2 +-
 UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c     | 18 +++++++++---------
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c
index 4baba1e9f8dc..f957de1f4764 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c
@@ -344,7 +344,7 @@ SmmInitHandler (
   AsmWriteIdtr (&gcSmiIdtr);
   ApicId = GetApicId ();
 
-  ASSERT (mNumberOfCpus <= PcdGet32 (PcdCpuMaxLogicalProcessorNumber));
+  ASSERT (mNumberOfCpus <= mMaxNumberOfCpus);
 
   for (Index = 0; Index < mNumberOfCpus; Index++) {
     if (ApicId == (UINT32)gSmmCpuPrivate->ProcessorInfo[Index].ProcessorId) { diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c
index c1a48d100e0f..f53819ee24c2 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c
@@ -139,7 +139,7 @@ GetCpuIndex (
 
   ApicId = GetApicId ();
 
-  for (Index = 0; Index < PcdGet32 (PcdCpuMaxLogicalProcessorNumber); Index++) {
+  for (Index = 0; Index < mMaxNumberOfCpus; Index++) {
     if (gSmmCpuPrivate->ProcessorInfo[Index].ProcessorId == ApicId) {
       return Index;
     }
@@ -825,13 +825,13 @@ InitSmmProfileInternal (
   UINTN                      MsrDsAreaSizePerCpu;
   UINTN                      TotalSize;
 
-  mPFEntryCount = (UINTN *)AllocateZeroPool (sizeof (UINTN) * PcdGet32 (PcdCpuMaxLogicalProcessorNumber));
+  mPFEntryCount = (UINTN *)AllocateZeroPool (sizeof (UINTN) * 
+ mMaxNumberOfCpus);
   ASSERT (mPFEntryCount != NULL);
   mLastPFEntryValue = (UINT64  (*)[MAX_PF_ENTRY_COUNT])AllocateZeroPool (
-                                                         sizeof (mLastPFEntryValue[0]) * PcdGet32 (PcdCpuMaxLogicalProcessorNumber));
+                                                         sizeof 
+ (mLastPFEntryValue[0]) * mMaxNumberOfCpus);
   ASSERT (mLastPFEntryValue != NULL);
   mLastPFEntryPointer = (UINT64 *(*)[MAX_PF_ENTRY_COUNT])AllocateZeroPool (
-                                                           sizeof (mLastPFEntryPointer[0]) * PcdGet32 (PcdCpuMaxLogicalProcessorNumber));
+                                                           sizeof 
+ (mLastPFEntryPointer[0]) * mMaxNumberOfCpus);
   ASSERT (mLastPFEntryPointer != NULL);
 
   //
@@ -872,17 +872,17 @@ InitSmmProfileInternal (
   mSmmProfileBase->NumCpus        = gSmmCpuPrivate->SmmCoreEntryContext.NumberOfCpus;
 
   if (mBtsSupported) {
-    mMsrDsArea = (MSR_DS_AREA_STRUCT **)AllocateZeroPool (sizeof (MSR_DS_AREA_STRUCT *) * PcdGet32 (PcdCpuMaxLogicalProcessorNumber));
+    mMsrDsArea = (MSR_DS_AREA_STRUCT **)AllocateZeroPool (sizeof 
+ (MSR_DS_AREA_STRUCT *) * mMaxNumberOfCpus);
     ASSERT (mMsrDsArea != NULL);
-    mMsrBTSRecord = (BRANCH_TRACE_RECORD **)AllocateZeroPool (sizeof (BRANCH_TRACE_RECORD *) * PcdGet32 (PcdCpuMaxLogicalProcessorNumber));
+    mMsrBTSRecord = (BRANCH_TRACE_RECORD **)AllocateZeroPool (sizeof 
+ (BRANCH_TRACE_RECORD *) * mMaxNumberOfCpus);
     ASSERT (mMsrBTSRecord != NULL);
-    mMsrPEBSRecord = (PEBS_RECORD **)AllocateZeroPool (sizeof (PEBS_RECORD *) * PcdGet32 (PcdCpuMaxLogicalProcessorNumber));
+    mMsrPEBSRecord = (PEBS_RECORD **)AllocateZeroPool (sizeof 
+ (PEBS_RECORD *) * mMaxNumberOfCpus);
     ASSERT (mMsrPEBSRecord != NULL);
 
     mMsrDsAreaBase  = (MSR_DS_AREA_STRUCT *)((UINTN)Base + mSmmProfileSize);
-    MsrDsAreaSizePerCpu = mMsrDsAreaSize / PcdGet32 (PcdCpuMaxLogicalProcessorNumber);
+    MsrDsAreaSizePerCpu = mMsrDsAreaSize / mMaxNumberOfCpus;
     mBTSRecordNumber    = (MsrDsAreaSizePerCpu - sizeof(PEBS_RECORD) * PEBS_RECORD_NUMBER - sizeof(MSR_DS_AREA_STRUCT)) / sizeof(BRANCH_TRACE_RECORD);
-    for (Index = 0; Index < PcdGet32 (PcdCpuMaxLogicalProcessorNumber); Index++) {
+    for (Index = 0; Index < mMaxNumberOfCpus; Index++) {
       mMsrDsArea[Index]     = (MSR_DS_AREA_STRUCT *)((UINTN)mMsrDsAreaBase + MsrDsAreaSizePerCpu * Index);
       mMsrBTSRecord[Index]  = (BRANCH_TRACE_RECORD *)((UINTN)mMsrDsArea[Index] + sizeof(MSR_DS_AREA_STRUCT));
       mMsrPEBSRecord[Index] = (PEBS_RECORD *)((UINTN)mMsrDsArea[Index] + MsrDsAreaSizePerCpu - sizeof(PEBS_RECORD) * PEBS_RECORD_NUMBER);
--
2.9.2