OvmfPkg: define CPU_HOT_EJECT_DATA

Define CPU_HOT_EJECT_DATA and add PCD PcdCpuHotEjectDataAddress, which
will be used to share CPU ejection state between OvmfPkg/CpuHotPlugSmm
and PiSmmCpuDxeSmm.

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>
Message-Id: <20210312062656.2477515-6-ankur.a.arora@oracle.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

OvmfPkg/Include/Pcd/CpuHotEjectData.h

@@ -0,0 +1,60 @@
+/** @file
+  Definition for the CPU_HOT_EJECT_DATA structure, which shares
+  CPU hot-eject state between OVMF's SmmCpuFeaturesLib instance in
+  PiSmmCpuDxeSmm, and CpuHotplugSmm.
+
+  CPU_HOT_EJECT_DATA is allocated in SMRAM, and pointed-to by
+  PcdCpuHotEjectDataAddress.
+
+  PcdCpuHotEjectDataAddress is valid when SMM_REQUIRE is TRUE
+  and PcdCpuMaxLogicalProcessorNumber > 1.
+
+  Copyright (C) 2021, Oracle Corporation.
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#ifndef CPU_HOT_EJECT_DATA_H_
+#define CPU_HOT_EJECT_DATA_H_
+
+/**
+  CPU Hot-eject handler, called from SmmCpuFeaturesRendezvousExit()
+  on each CPU at exit from SMM.
+
+  @param[in] ProcessorNum      ProcessorNum denotes the CPU exiting SMM,
+                               and will be used as an index into
+                               CPU_HOT_EJECT_DATA->QemuSelectorMap. It is
+                               identical to the processor handle in
+                               EFI_SMM_CPU_SERVICE_PROTOCOL.
+**/
+typedef
+VOID
+(EFIAPI *CPU_HOT_EJECT_HANDLER) (
+  IN UINTN  ProcessorNum
+  );
+
+//
+// CPU_EJECT_QEMU_SELECTOR_INVALID marks CPUs not being ejected in
+// CPU_HOT_EJECT_DATA->QemuSelectorMap.
+//
+// QEMU CPU Selector is UINT32, so we choose an invalid value larger
+// than that type.
+//
+#define CPU_EJECT_QEMU_SELECTOR_INVALID       (MAX_UINT64)
+
+typedef struct {
+  //
+  // Maps ProcessorNum -> QemuSelector for pending hot-ejects
+  //
+  volatile UINT64 *QemuSelectorMap;
+  //
+  // Handler to do the CPU ejection
+  //
+  volatile CPU_HOT_EJECT_HANDLER Handler;
+  //
+  // Entries in the QemuSelectorMap
+  //
+  UINT32 ArrayLength;
+} CPU_HOT_EJECT_DATA;
+
+#endif // CPU_HOT_EJECT_DATA_H_

OvmfPkg/OvmfPkg.dec

@@ -352,6 +352,10 @@
   #  This PCD is only accessed if PcdSmmSmramRequire is TRUE (see below).
   gUefiOvmfPkgTokenSpaceGuid.PcdQ35SmramAtDefaultSmbase|FALSE|BOOLEAN|0x34
 
+  ## This PCD adds a communication channel between OVMF's SmmCpuFeaturesLib
+  #  instance in PiSmmCpuDxeSmm, and CpuHotplugSmm.
+  gUefiOvmfPkgTokenSpaceGuid.PcdCpuHotEjectDataAddress|0|UINT64|0x46
+
 [PcdsFeatureFlag]
   gUefiOvmfPkgTokenSpaceGuid.PcdQemuBootOrderPciTranslation|TRUE|BOOLEAN|0x1c
   gUefiOvmfPkgTokenSpaceGuid.PcdQemuBootOrderMmioTranslation|FALSE|BOOLEAN|0x1d