OvmfPkg/CpuHotplugSmm: refactor hotplug logic

Refactor CpuHotplugMmi() to pull out the CPU hotplug logic into
ProcessHotAddedCpus(). This is in preparation for supporting CPU
hot-unplug.

Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Aaron Young <aaron.young@oracle.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3132
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20210312062656.2477515-2-ankur.a.arora@oracle.com>

1 files changed, 126 insertions, 84 deletions

diff --git a/OvmfPkg/CpuHotplugSmm/CpuHotplug.c b/OvmfPkg/CpuHotplugSmm/CpuHotplug.c
index cfe698ed2b..bf68fcd429 100644
--- a/OvmfPkg/CpuHotplugSmm/CpuHotplug.c
+++ b/OvmfPkg/CpuHotplugSmm/CpuHotplug.c
@@ -62,6 +62,129 @@ STATIC UINT32 mPostSmmPenAddress;
 //

 STATIC EFI_HANDLE mDispatchHandle;

 

+/**

+  Process CPUs that have been hot-added, per QemuCpuhpCollectApicIds().

+

+  For each such CPU, relocate the SMBASE, and report the CPU to PiSmmCpuDxeSmm

+  via EFI_SMM_CPU_SERVICE_PROTOCOL. If the supposedly hot-added CPU is already

+  known, skip it silently.

+

+  @param[in] PluggedApicIds    The APIC IDs of the CPUs that have been

+                               hot-plugged.

+

+  @param[in] PluggedCount      The number of filled-in APIC IDs in

+                               PluggedApicIds.

+

+  @retval EFI_SUCCESS          CPUs corresponding to all the APIC IDs are

+                               populated.

+

+  @retval EFI_OUT_OF_RESOURCES Out of APIC ID space in "mCpuHotPlugData".

+

+  @return                      Error codes propagated from SmbaseRelocate()

+                               and mMmCpuService->AddProcessor().

+**/

+STATIC

+EFI_STATUS

+ProcessHotAddedCpus (

+  IN APIC_ID                      *PluggedApicIds,

+  IN UINT32                       PluggedCount

+  )

+{

+  EFI_STATUS Status;

+  UINT32     PluggedIdx;

+  UINT32     NewSlot;

+

+  //

+  // The Post-SMM Pen need not be reinstalled multiple times within a single

+  // root MMI handling. Even reinstalling once per root MMI is only prudence;

+  // in theory installing the pen in the driver's entry point function should

+  // suffice.

+  //

+  SmbaseReinstallPostSmmPen (mPostSmmPenAddress);

+

+  PluggedIdx = 0;

+  NewSlot = 0;

+  while (PluggedIdx < PluggedCount) {

+    APIC_ID NewApicId;

+    UINT32  CheckSlot;

+    UINTN   NewProcessorNumberByProtocol;

+

+    NewApicId = PluggedApicIds[PluggedIdx];

+

+    //

+    // Check if the supposedly hot-added CPU is already known to us.

+    //

+    for (CheckSlot = 0;

+         CheckSlot < mCpuHotPlugData->ArrayLength;

+         CheckSlot++) {

+      if (mCpuHotPlugData->ApicId[CheckSlot] == NewApicId) {

+        break;

+      }

+    }

+    if (CheckSlot < mCpuHotPlugData->ArrayLength) {

+      DEBUG ((DEBUG_VERBOSE, "%a: APIC ID " FMT_APIC_ID " was hot-plugged "

+        "before; ignoring it\n", __FUNCTION__, NewApicId));

+      PluggedIdx++;

+      continue;

+    }

+

+    //

+    // Find the first empty slot in CPU_HOT_PLUG_DATA.

+    //

+    while (NewSlot < mCpuHotPlugData->ArrayLength &&

+           mCpuHotPlugData->ApicId[NewSlot] != MAX_UINT64) {

+      NewSlot++;

+    }

+    if (NewSlot == mCpuHotPlugData->ArrayLength) {

+      DEBUG ((DEBUG_ERROR, "%a: no room for APIC ID " FMT_APIC_ID "\n",

+        __FUNCTION__, NewApicId));

+      return EFI_OUT_OF_RESOURCES;

+    }

+

+    //

+    // Store the APIC ID of the new processor to the slot.

+    //

+    mCpuHotPlugData->ApicId[NewSlot] = NewApicId;

+

+    //

+    // Relocate the SMBASE of the new CPU.

+    //

+    Status = SmbaseRelocate (NewApicId, mCpuHotPlugData->SmBase[NewSlot],

+               mPostSmmPenAddress);

+    if (EFI_ERROR (Status)) {

+      goto RevokeNewSlot;

+    }

+

+    //

+    // Add the new CPU with EFI_SMM_CPU_SERVICE_PROTOCOL.

+    //

+    Status = mMmCpuService->AddProcessor (mMmCpuService, NewApicId,

+                              &NewProcessorNumberByProtocol);

+    if (EFI_ERROR (Status)) {

+      DEBUG ((DEBUG_ERROR, "%a: AddProcessor(" FMT_APIC_ID "): %r\n",

+        __FUNCTION__, NewApicId, Status));

+      goto RevokeNewSlot;

+    }

+

+    DEBUG ((DEBUG_INFO, "%a: hot-added APIC ID " FMT_APIC_ID ", SMBASE 0x%Lx, "

+      "EFI_SMM_CPU_SERVICE_PROTOCOL assigned number %Lu\n", __FUNCTION__,

+      NewApicId, (UINT64)mCpuHotPlugData->SmBase[NewSlot],

+      (UINT64)NewProcessorNumberByProtocol));

+

+    NewSlot++;

+    PluggedIdx++;

+  }

+

+  //

+  // We've processed this batch of hot-added CPUs.

+  //

+  return EFI_SUCCESS;

+

+RevokeNewSlot:

+  mCpuHotPlugData->ApicId[NewSlot] = MAX_UINT64;

+

+  return Status;

+}

 

 /**

   CPU Hotplug MMI handler function.

@@ -122,8 +245,6 @@ CpuHotplugMmi (
   UINT8      ApmControl;

   UINT32     PluggedCount;

   UINT32     ToUnplugCount;

-  UINT32     PluggedIdx;

-  UINT32     NewSlot;

 

   //

   // Assert that we are entering this function due to our root MMI handler

@@ -179,87 +300,11 @@ CpuHotplugMmi (
     goto Fatal;

   }

 

-  //

-  // Process hot-added CPUs.

-  //

-  // The Post-SMM Pen need not be reinstalled multiple times within a single

-  // root MMI handling. Even reinstalling once per root MMI is only prudence;

-  // in theory installing the pen in the driver's entry point function should

-  // suffice.

-  //

-  SmbaseReinstallPostSmmPen (mPostSmmPenAddress);

-

-  PluggedIdx = 0;

-  NewSlot = 0;

-  while (PluggedIdx < PluggedCount) {

-    APIC_ID NewApicId;

-    UINT32  CheckSlot;

-    UINTN   NewProcessorNumberByProtocol;

-

-    NewApicId = mPluggedApicIds[PluggedIdx];

-

-    //

-    // Check if the supposedly hot-added CPU is already known to us.

-    //

-    for (CheckSlot = 0;

-         CheckSlot < mCpuHotPlugData->ArrayLength;

-         CheckSlot++) {

-      if (mCpuHotPlugData->ApicId[CheckSlot] == NewApicId) {

-        break;

-      }

-    }

-    if (CheckSlot < mCpuHotPlugData->ArrayLength) {

-      DEBUG ((DEBUG_VERBOSE, "%a: APIC ID " FMT_APIC_ID " was hot-plugged "

-        "before; ignoring it\n", __FUNCTION__, NewApicId));

-      PluggedIdx++;

-      continue;

-    }

-

-    //

-    // Find the first empty slot in CPU_HOT_PLUG_DATA.

-    //

-    while (NewSlot < mCpuHotPlugData->ArrayLength &&

-           mCpuHotPlugData->ApicId[NewSlot] != MAX_UINT64) {

-      NewSlot++;

-    }

-    if (NewSlot == mCpuHotPlugData->ArrayLength) {

-      DEBUG ((DEBUG_ERROR, "%a: no room for APIC ID " FMT_APIC_ID "\n",

-        __FUNCTION__, NewApicId));

-      goto Fatal;

-    }

-

-    //

-    // Store the APIC ID of the new processor to the slot.

-    //

-    mCpuHotPlugData->ApicId[NewSlot] = NewApicId;

-

-    //

-    // Relocate the SMBASE of the new CPU.

-    //

-    Status = SmbaseRelocate (NewApicId, mCpuHotPlugData->SmBase[NewSlot],

-               mPostSmmPenAddress);

-    if (EFI_ERROR (Status)) {

-      goto RevokeNewSlot;

-    }

-

-    //

-    // Add the new CPU with EFI_SMM_CPU_SERVICE_PROTOCOL.

-    //

-    Status = mMmCpuService->AddProcessor (mMmCpuService, NewApicId,

-                              &NewProcessorNumberByProtocol);

+  if (PluggedCount > 0) {

+    Status = ProcessHotAddedCpus (mPluggedApicIds, PluggedCount);

     if (EFI_ERROR (Status)) {

-      DEBUG ((DEBUG_ERROR, "%a: AddProcessor(" FMT_APIC_ID "): %r\n",

-        __FUNCTION__, NewApicId, Status));

-      goto RevokeNewSlot;

+      goto Fatal;

     }

-

-    DEBUG ((DEBUG_INFO, "%a: hot-added APIC ID " FMT_APIC_ID ", SMBASE 0x%Lx, "

-      "EFI_SMM_CPU_SERVICE_PROTOCOL assigned number %Lu\n", __FUNCTION__,

-      NewApicId, (UINT64)mCpuHotPlugData->SmBase[NewSlot],

-      (UINT64)NewProcessorNumberByProtocol));

-

-    NewSlot++;

-    PluggedIdx++;

   }

 

   //

@@ -267,9 +312,6 @@ CpuHotplugMmi (
   //

   return EFI_SUCCESS;

 

-RevokeNewSlot:

-  mCpuHotPlugData->ApicId[NewSlot] = MAX_UINT64;

-

 Fatal:

   ASSERT (FALSE);

   CpuDeadLoop ();