OvmfPkg/CpuS3DataDxe: enable S3 resume after CPU hotplug

OvmfPkg/CpuS3DataDxe: enable S3 resume after CPU hotplug

During normal boot, CpuS3DataDxe allocates

- an empty CPU_REGISTER_TABLE entry in the
  "ACPI_CPU_DATA.PreSmmInitRegisterTable" array, and

- an empty CPU_REGISTER_TABLE entry in the "ACPI_CPU_DATA.RegisterTable"
  array,

for every CPU whose APIC ID CpuS3DataDxe can learn.

Currently EFI_MP_SERVICES_PROTOCOL is used for both determining the number
of CPUs -- the protocol reports the present-at-boot CPU count --, and for
retrieving the APIC IDs of those CPUs.

Consequently, if a CPU is hot-plugged at OS runtime, then S3 resume
breaks. That's because PiSmmCpuDxeSmm will not find the hot-added CPU's
APIC ID associated with any CPU_REGISTER_TABLE object, in the SMRAM copies
of either of the "RegisterTable" and "PreSmmInitRegisterTable" arrays. The
failure to match the hot-added CPU's APIC ID trips the ASSERT() in
SetRegister() [UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c].

If "PcdQ35SmramAtDefaultSmbase" is TRUE, then:

- prepare CPU_REGISTER_TABLE objects for all possible CPUs, not just the
  present-at-boot CPUs (PlatformPei stored the possible CPU count to
  "PcdCpuMaxLogicalProcessorNumber");

- use QEMU_CPUHP_CMD_GET_ARCH_ID for filling in the "InitialApicId" fields
  of the CPU_REGISTER_TABLE objects.

This provides full APIC ID coverage for PiSmmCpuDxeSmm during S3 resume,
accommodating CPUs hot-added at OS runtime.

This patch is best reviewed with

$ git show -b

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1512
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200226221156.29589-17-lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>