[PATCH v7 05/10] OvmfPkg/CpuHotplugSmm: define CPU_HOT_EJECT_DATA

["Ankur Arora" <ankur.a.arora@oracle.com>]

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>
---

Notes:
    Addresses the following review comments in v6:
     (1) Dropped modifications to LibraryClasses in OvmfPkg.dec
     (2,3) Cleanup comments around PCD PcdCpuHotEjectDataAddress.
     (4) Move PCD PcdCpuHotEjectDataAddress declaration in CpuHotplugSmm.inf
      to a patch-7 where it actually gets used.
     (5a,5b) Change the comment in the top block to use Laszlo's language.
      Also detail when the PCD would contain a valid value.
     (6) Move Library/CpuHotEjectData.h to Pcd/CpuHotEjectData.h
     (7,15,16) Fixup guard macro to be C namespace compliant. Also fixup the
      comment style near the endif guard.
     (8-10) Rename CPU_HOT_EJECT_FN to a more EDK2 compliant style. Also add
      a comment block and fix spacing.
     () Rename ApicIdMap -> QemuSelectorMap while keeping the type as UINT64.
      Related to a comment in patch-8 ("... add worker to do CPU ejection".)
     (11a,11b) Rename CPU_EJECT_INVALID to CPU_EJECT_QEMU_SELECTOR_INVALID
      and add a comment about it.
     () Remove CPU_EJECT_WORKER based on review comment on a patch 8.
     (12,14) Remove CPU_HOT_EJECT_DATA fields Revision and Reserved.
      Reorder CPU_HOT_EJECT_DATA to minimize internal padding
      and ensure elements are properly aligned.
     (13a,13b) Change CpuIndex->ApicId map to ProcessorNum -> QemuSelector
     () Make CPU_HOT_EJECT_HANDLER->Handler,
      CPU_HOT_EJECT_HANDLER->QemuSelectorMap volatile.

 OvmfPkg/OvmfPkg.dec                   |  4 +++
 OvmfPkg/Include/Pcd/CpuHotEjectData.h | 52 +++++++++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+)
 create mode 100644 OvmfPkg/Include/Pcd/CpuHotEjectData.h

diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
index 4348bb45c64a..9629707020ba 100644
--- a/OvmfPkg/OvmfPkg.dec
+++ b/OvmfPkg/OvmfPkg.dec
@@ -352,6 +352,10 @@ [PcdsDynamic, PcdsDynamicEx]
   #  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
diff --git a/OvmfPkg/Include/Pcd/CpuHotEjectData.h b/OvmfPkg/Include/Pcd/CpuHotEjectData.h
new file mode 100644
index 000000000000..024a92726869
--- /dev/null
+++ b/OvmfPkg/Include/Pcd/CpuHotEjectData.h
@@ -0,0 +1,52 @@
+/** @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 MaxNumberOfCpus > 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 {
+  volatile UINT64       *QemuSelectorMap; // Maps ProcessorNum -> QemuSelector
+                                          // for pending hot-ejects
+  volatile CPU_HOT_EJECT_HANDLER Handler; // Handler to do the CPU ejection
+  UINT32                ArrayLength;      // Entries in the QemuSelectorMap
+} CPU_HOT_EJECT_DATA;
+
+#endif // CPU_HOT_EJECT_DATA_H_
-- 
2.9.3