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From: "Ankur Arora" <ankur.a.arora@oracle.com>
To: devel@edk2.groups.io
Cc: lersek@redhat.com, imammedo@redhat.com,
	boris.ostrovsky@oracle.com,
	Ankur Arora <ankur.a.arora@oracle.com>,
	Eric Dong <eric.dong@intel.com>, Ray Ni <ray.ni@intel.com>,
	Rahul Kumar <rahul1.kumar@intel.com>,
	Aaron Young <aaron.young@oracle.com>
Subject: [PATCH v2 06/10] UefiCpuPkg/PiSmmCpuDxeSmm: initialize IsBsp
Date: Thu,  7 Jan 2021 11:55:11 -0800	[thread overview]
Message-ID: <20210107195515.106158-7-ankur.a.arora@oracle.com> (raw)
In-Reply-To: <20210107195515.106158-1-ankur.a.arora@oracle.com>

Initialize IsBsp early to ensure that this variable reflects the BSP
status correctly.

Also replace this check:
  if (mSmmMpSyncData->BspIndex == (UINT32)CpuIndex)

with:
  if (IsBsp)

Note that there's a window of time when these two diverge, when the BSP,
at exit from BSPHandler(), resets mSmmMpSyncData->BspIndex.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Rahul Kumar <rahul1.kumar@intel.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>
---
 UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
index 4bcd217917d7..e7ea44eb86fc 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
@@ -1565,7 +1565,12 @@ SmiRendezvous (
 {
   EFI_STATUS                     Status;
   BOOLEAN                        ValidSmi;
-  BOOLEAN                        IsBsp;
+
+  //
+  // IsBsp starts out as false. Once a CPU gets elected as BSP,
+  // it will transition its value to true.
+  //
+  BOOLEAN                        IsBsp = FALSE;
   BOOLEAN                        BspInProgress;
   UINTN                          Index;
   UINTN                          Cr2;
@@ -1656,7 +1661,6 @@ SmiRendezvous (
       //
       // Elect BSP
       //
-      IsBsp = FALSE;
       if (FeaturePcdGet (PcdCpuSmmEnableBspElection)) {
         if (!mSmmMpSyncData->SwitchBsp || mSmmMpSyncData->CandidateBsp[CpuIndex]) {
           //
@@ -1679,6 +1683,8 @@ SmiRendezvous (
               (UINT32)-1,
               (UINT32)CpuIndex
               );
+
+            IsBsp = mSmmMpSyncData->BspIndex == (UINT32)CpuIndex;
           }
         }
       }
@@ -1686,7 +1692,7 @@ SmiRendezvous (
       //
       // "mSmmMpSyncData->BspIndex == CpuIndex" means this is the BSP
       //
-      if (mSmmMpSyncData->BspIndex == CpuIndex) {
+      if (IsBsp) {
 
         //
         // Clear last request for SwitchBsp.
-- 
2.9.3


  parent reply	other threads:[~2021-01-07 19:55 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-07 19:55 [PATCH v2 00/10] support CPU hot-unplug Ankur Arora
2021-01-07 19:55 ` [PATCH v2 01/10] OvmfPkg/CpuHotplugSmm: move CPU Hotplug into PlugCpus() Ankur Arora
2021-01-07 19:55 ` [PATCH v2 02/10] OvmfPkg/CpuHotplugSmm: handle Hot-unplug events Ankur Arora
2021-01-07 19:55 ` [PATCH v2 03/10] OvmfPkg/CpuHotplugSmm: add Qemu CpuStatus helper Ankur Arora
2021-01-07 19:55 ` [PATCH v2 04/10] OvmfPkg/CpuHotplugSmm: handle CPU hot-unplug Ankur Arora
2021-01-07 19:55 ` [PATCH v2 05/10] MdePkg: add MmRegisterShutdownInterface() Ankur Arora
2021-01-07 20:48   ` [edk2-devel] " Laszlo Ersek
2021-01-07 21:00     ` Laszlo Ersek
2021-01-07 21:19     ` Ankur Arora
2021-01-07 21:50       ` Laszlo Ersek
2021-01-07 21:45     ` Laszlo Ersek
2021-01-07 23:42       ` Ankur Arora
2021-01-07 19:55 ` Ankur Arora [this message]
2021-01-07 19:55 ` [PATCH v2 07/10] UefiCpuPkg/SmmCpuFeaturesLib: add IsBsp as a param to SmmCpuFeaturesRendezvousExit() Ankur Arora
2021-01-07 19:55 ` [PATCH v2 08/10] OvmfCpuPkg/CpuHotplug: add a hot-unplug handler called at SMI exit Ankur Arora
2021-01-07 19:55 ` [PATCH v2 09/10] OvmfPkg/SmmControl2Dxe: negotiate ICH9_LPC_SMI_F_CPU_HOT_UNPLUG Ankur Arora
2021-01-07 19:55 ` [PATCH v2 10/10] MdePkg: use CpuPause() in CpuDeadLoop() Ankur Arora
2021-01-07 22:30   ` [edk2-devel] " Michael D Kinney
2021-01-07 23:43     ` Ankur Arora

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