[PATCHv12,00/19] x86/tdx: Add kexec support

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.

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

v12:
  - Drop 'crash' argument from x86_guest::enc_kexec_begin();
  - Rework CR4 setting in identity_mapped();
  - Fix comments and commit message.
  - Add review tags;
v11:
  - Rebased onto current tip/master;
  - Rename CONFIG_X86_ACPI_MADT_WAKEUP to CONFIG_ACPI_MADT_WAKEUP;
  - Drop CC_ATTR_GUEST_MEM_ENCRYPT checks around x86_platform.guest.enc_kexec_*
    callbacks;
  - Rename x86_platform.guest.enc_kexec_* callbacks;
  - Report error code in case of vmm call fail in __set_memory_enc_pgtable();
  - Update commit messages and comments;
  - Add Reviewed-bys;
v10:
  - Rebased to current tip/master;
  - Preserve CR4.MCE instead of setting it unconditionally;
  - Fix build error in Hyper-V code after rebase;
  - Include Ashish's patch for real;
v9:
  - Rebased;
  - Keep page tables that maps E820_TYPE_ACPI (Ashish);
  - Ack/Reviewed/Tested-bys from Sathya, Kai, Tao;
  - Minor printk() message adjustments;
v8:
  - Rework serialization of around conversion memory back to private;
  - Print ACPI_MADT_TYPE_MULTIPROC_WAKEUP in acpi_table_print_madt_entry();
  - Drop debugfs interface to dump info on shared memory;
  - Adjust comments and commit messages;
  - Reviewed-bys by Baoquan, Dave and Thomas;
v7:
  - Call enc_kexec_stop_conversion() and enc_kexec_unshare_mem() after shutting
    down IO-APIC, lapic and hpet. It meets AMD requirements.
  - Minor style changes;
  - Add Acked/Reviewed-bys;
v6:
  - Rebased to v6.8-rc1;
  - Provide default noop callbacks from .enc_kexec_stop_conversion and
    .enc_kexec_unshare_mem;
  - Split off patch that introduces .enc_kexec_* callbacks;
  - asm_acpi_mp_play_dead(): program CR3 directly from RSI, no MOV to RAX
    required;
  - Restructure how smp_ops.stop_this_cpu() hooked up in crash_nmi_callback();
  - kvmclock patch got merged via KVM tree;
v5:
  - Rename smp_ops.crash_play_dead to smp_ops.stop_this_cpu and use it in
    stop_this_cpu();
  - Split off enc_kexec_stop_conversion() from enc_kexec_unshare_mem();
  - Introduce kernel_ident_mapping_free();
  - Add explicit include for alternatives and stringify.
  - Add barrier() after setting conversion_allowed to false;
  - Mark cpu_hotplug_offline_disabled __ro_after_init;
  - Print error if failed to hand over CPU to BIOS;
  - Update comments and commit messages;
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;

Ashish Kalra (1):
  x86/mm: Do not zap page table entries mapping unaccepted memory table
    during kdump.

Borislav Petkov (1):
  x86/relocate_kernel: Use named labels for less confusion

Kirill A. Shutemov (17):
  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/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/mm: Add callbacks to prepare encrypted memory for kexec
  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/smp: Add smp_ops.stop_this_cpu() callback
  x86/mm: Introduce kernel_ident_mapping_free()
  x86/acpi: Add support for CPU offlining for ACPI MADT wakeup method
  ACPI: tables: Print MULTIPROC_WAKEUP when MADT is parsed

 arch/x86/Kconfig                     |   7 +
 arch/x86/coco/core.c                 |   1 -
 arch/x86/coco/tdx/tdx.c              | 121 ++++++++++-
 arch/x86/hyperv/ivm.c                |  22 +-
 arch/x86/include/asm/acpi.h          |   7 +
 arch/x86/include/asm/init.h          |   3 +
 arch/x86/include/asm/pgtable.h       |   5 +
 arch/x86/include/asm/pgtable_types.h |   1 +
 arch/x86/include/asm/set_memory.h    |   3 +
 arch/x86/include/asm/smp.h           |   1 +
 arch/x86/include/asm/x86_init.h      |  14 +-
 arch/x86/kernel/acpi/Makefile        |   1 +
 arch/x86/kernel/acpi/boot.c          |  86 +-------
 arch/x86/kernel/acpi/madt_playdead.S |  28 +++
 arch/x86/kernel/acpi/madt_wakeup.c   | 292 +++++++++++++++++++++++++++
 arch/x86/kernel/crash.c              |  12 ++
 arch/x86/kernel/e820.c               |   9 +-
 arch/x86/kernel/process.c            |   7 +
 arch/x86/kernel/reboot.c             |  18 ++
 arch/x86/kernel/relocate_kernel_64.S |  24 ++-
 arch/x86/kernel/x86_init.c           |   8 +-
 arch/x86/mm/ident_map.c              |  73 +++++++
 arch/x86/mm/init_64.c                |  16 +-
 arch/x86/mm/mem_encrypt_amd.c        |   8 +-
 arch/x86/mm/pat/set_memory.c         |  75 +++++--
 drivers/acpi/tables.c                |  14 ++
 include/acpi/actbl2.h                |  19 +-
 include/linux/cc_platform.h          |  10 -
 include/linux/cpuhplock.h            |   2 +
 kernel/cpu.c                         |  12 +-
 30 files changed, 733 insertions(+), 166 deletions(-)
 create mode 100644 arch/x86/kernel/acpi/madt_playdead.S
 create mode 100644 arch/x86/kernel/acpi/madt_wakeup.c