[PATCHv4 00/14] x86/tdx: Add kexec support

["Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>]

The patchset adds bits and pieces to get kexec (and crashkernel) work on
TDX guest.

The last patch implements CPU offlining according to the approved ACPI
spec change poposal[1]. It unlocks kexec with all CPUs visible in the target
kernel. It requires BIOS-side enabling. If it missing we fallback to booting
2nd kernel with single CPU.

Please review. I would be glad for any feedback.

v4:
  - Fix build for !KEXEC_CORE;
  - Cleaner ATLERNATIVE use;
  - Update commit messages and comments;
  - Add Reviewed-bys;
v3:
  - Rework acpi_mp_crash_stop_other_cpus() to avoid invoking hotplug state
    machine;
  - Free page tables if reset vector setup failed;
  - Change asm_acpi_mp_play_dead() to pass reset vector and PGD as arguments;
  - Mark acpi_mp_* variables as static and __ro_after_init;
  - Use u32 for apicid;
  - Disable CPU offlining if reset vector setup failed;
  - Rename madt.S -> madt_playdead.S;
  - Mark tdx_kexec_unshare_mem() as static;
  - Rebase onto up-to-date tip/master;
  - Whitespace fixes;
  - Reorder patches;
  - Add Reviewed-bys;
  - Update comments and commit messages;
v2:
  - Rework how unsharing hook ups into kexec codepath;
  - Rework kvmclock_disable() fix based on Sean's;
  - s/cpu_hotplug_not_supported()/cpu_hotplug_disable_offlining()/;
  - use play_dead_common() to implement acpi_mp_play_dead();
  - cond_resched() in tdx_shared_memory_show();
  - s/target kernel/second kernel/;
  - Update commit messages and comments;

[1] https://lore.kernel.org/all/13356251.uLZWGnKmhe@kreacher

Kirill A. Shutemov (14):
  x86/acpi: Extract ACPI MADT wakeup code into a separate file
  x86/apic: Mark acpi_mp_wake_* variables as __ro_after_init
  cpu/hotplug: Add support for declaring CPU offlining not supported
  cpu/hotplug, x86/acpi: Disable CPU offlining for ACPI MADT wakeup
  x86/kvm: Do not try to disable kvmclock if it was not enabled
  x86/kexec: Keep CR4.MCE set during kexec for TDX guest
  x86/mm: Make x86_platform.guest.enc_status_change_*() return errno
  x86/mm: Return correct level from lookup_address() if pte is none
  x86/tdx: Account shared memory
  x86/tdx: Convert shared memory back to private on kexec
  x86/mm: Make e820_end_ram_pfn() cover E820_TYPE_ACPI ranges
  x86/acpi: Rename fields in acpi_madt_multiproc_wakeup structure
  x86/acpi: Do not attempt to bring up secondary CPUs in kexec case
  x86/acpi: Add support for CPU offlining for ACPI MADT wakeup method

 arch/x86/Kconfig                     |   7 +
 arch/x86/coco/core.c                 |   1 -
 arch/x86/coco/tdx/kexec.c            |   0
 arch/x86/coco/tdx/tdx.c              | 205 ++++++++++++++-
 arch/x86/hyperv/ivm.c                |   9 +-
 arch/x86/include/asm/acpi.h          |   5 +
 arch/x86/include/asm/pgtable_types.h |   1 +
 arch/x86/include/asm/smp.h           |   1 +
 arch/x86/include/asm/x86_init.h      |   5 +-
 arch/x86/kernel/acpi/Makefile        |  11 +-
 arch/x86/kernel/acpi/boot.c          |  86 +------
 arch/x86/kernel/acpi/madt_playdead.S |  21 ++
 arch/x86/kernel/acpi/madt_wakeup.c   | 363 +++++++++++++++++++++++++++
 arch/x86/kernel/crash.c              |   4 +
 arch/x86/kernel/e820.c               |   9 +-
 arch/x86/kernel/kvmclock.c           |  12 +-
 arch/x86/kernel/reboot.c             |  22 +-
 arch/x86/kernel/relocate_kernel_64.S |   3 +
 arch/x86/kernel/x86_init.c           |   4 +-
 arch/x86/mm/mem_encrypt_amd.c        |   8 +-
 arch/x86/mm/pat/set_memory.c         |  17 +-
 include/acpi/actbl2.h                |  19 +-
 include/linux/cc_platform.h          |  10 -
 include/linux/cpu.h                  |   2 +
 kernel/cpu.c                         |  12 +-
 25 files changed, 689 insertions(+), 148 deletions(-)
 create mode 100644 arch/x86/coco/tdx/kexec.c
 create mode 100644 arch/x86/kernel/acpi/madt_playdead.S
 create mode 100644 arch/x86/kernel/acpi/madt_wakeup.c

-- 
2.41.0