UefiCpuPkg/MpInitLib: wait no longer than necessary for initial AP startup

Sometimes a platform knows exactly how many CPUs it has at boot. It should
be able to
- set PcdCpuMaxLogicalProcessorNumber dynamically to this number,
- set PcdCpuApInitTimeOutInMicroSeconds to a very long time (for example
  MAX_UINT32, approx. 71 minutes),
- and expect that MpInitLib wait exactly as long as necessary for all APs
  to report in.

Other platforms should be able to continue setting a reasonably large
upper bound on supported CPUs, and waiting for a reasonable, fixed amount
of time for all APs to report in.

Add this functionality. The TimedWaitForApFinish() function will return
when all APs have reported in, or the timeout has expired -- whichever
happens first.

(Accessing these PCDs dynamically is safe. The PEI and DXE phase instances
of this library are restricted to PEIM and DXE_DRIVER client modules, thus
the PCD accesses cannot be linked into runtime code.)

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>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Jeff Fan <jeff.fan@intel.com>

diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index 15dbfa1e7d6c7f5e9d85d88e0030c38ea65f4a40..ed22ce67782ef48b1148b5aac9868b1789a30e50 100644 (file)
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -683,6 +683,21 @@ FillExchangeInfoData (
   AsmReadIdtr ((IA32_DESCRIPTOR *) &ExchangeInfo->IdtrProfile);\r
 }\r
 \r
+/**\r
+  Helper function that waits until the finished AP count reaches the specified\r
+  limit, or the specified timeout elapses (whichever comes first).\r
+\r
+  @param[in] CpuMpData        Pointer to CPU MP Data.\r
+  @param[in] FinishedApLimit  The number of finished APs to wait for.\r
+  @param[in] TimeLimit        The number of microseconds to wait for.\r
+**/\r
+VOID\r
+TimedWaitForApFinish (\r
+  IN CPU_MP_DATA               *CpuMpData,\r
+  IN UINT32                    FinishedApLimit,\r
+  IN UINT32                    TimeLimit\r
+  );\r
+\r
 /**\r
   This function will be called by BSP to wakeup AP.\r
 \r
@@ -748,7 +763,11 @@ WakeUpAP (
       //\r
       // Wait for all potential APs waken up in one specified period\r
       //\r
-      MicroSecondDelay (PcdGet32(PcdCpuApInitTimeOutInMicroSeconds));\r
+      TimedWaitForApFinish (\r
+        CpuMpData,\r
+        PcdGet32 (PcdCpuMaxLogicalProcessorNumber) - 1,\r
+        PcdGet32 (PcdCpuApInitTimeOutInMicroSeconds)\r
+        );\r
     } else {\r
       //\r
       // Wait all APs waken up if this is not the 1st broadcast of SIPI\r
@@ -894,6 +913,58 @@ CheckTimeout (
   return FALSE;\r
 }\r
 \r
+/**\r
+  Helper function that waits until the finished AP count reaches the specified\r
+  limit, or the specified timeout elapses (whichever comes first).\r
+\r
+  @param[in] CpuMpData        Pointer to CPU MP Data.\r
+  @param[in] FinishedApLimit  The number of finished APs to wait for.\r
+  @param[in] TimeLimit        The number of microseconds to wait for.\r
+**/\r
+VOID\r
+TimedWaitForApFinish (\r
+  IN CPU_MP_DATA               *CpuMpData,\r
+  IN UINT32                    FinishedApLimit,\r
+  IN UINT32                    TimeLimit\r
+  )\r
+{\r
+  //\r
+  // CalculateTimeout() and CheckTimeout() consider a TimeLimit of 0\r
+  // "infinity", so check for (TimeLimit == 0) explicitly.\r
+  //\r
+  if (TimeLimit == 0) {\r
+    return;\r
+  }\r
+\r
+  CpuMpData->TotalTime = 0;\r
+  CpuMpData->ExpectedTime = CalculateTimeout (\r
+                              TimeLimit,\r
+                              &CpuMpData->CurrentTime\r
+                              );\r
+  while (CpuMpData->FinishedCount < FinishedApLimit &&\r
+         !CheckTimeout (\r
+            &CpuMpData->CurrentTime,\r
+            &CpuMpData->TotalTime,\r
+            CpuMpData->ExpectedTime\r
+            )) {\r
+    CpuPause ();\r
+  }\r
+\r
+  if (CpuMpData->FinishedCount >= FinishedApLimit) {\r
+    DEBUG ((\r
+      DEBUG_VERBOSE,\r
+      "%a: reached FinishedApLimit=%u in %Lu microseconds\n",\r
+      __FUNCTION__,\r
+      FinishedApLimit,\r
+      DivU64x64Remainder (\r
+        MultU64x32 (CpuMpData->TotalTime, 1000000),\r
+        GetPerformanceCounterProperties (NULL, NULL),\r
+        NULL\r
+        )\r
+      ));\r
+  }\r
+}\r
+\r
 /**\r
   Reset an AP to Idle state.\r
 \r