[PATCH v16 0/8] Parallel CPU bringup for x86_64

[Usama Arif <usama.arif@bytedance.com>]

This version includes the following changes over v15:
- Roll back to CPUHP_OFFLINE on failure in parallel bringup case.
- Release trampoline_lock earlier, just before setup_gdt.
- Rebase to x86/apic, Linux 6.3-rc3 with no change in boot time
  improvement over v15.
  (This already has some of the commits from v15 merged).

Thanks,
Usama

Changes across versions:
v2: Cut it back to just INIT/SIPI/SIPI in parallel for now, nothing more
v3: Clean up x2apic patch, add MTRR optimisation, lock topology update
    in preparation for more parallelisation.
v4: Fixes to the real mode parallelisation patch spotted by SeanC, to
    avoid scribbling on initial_gs in common_cpu_up(), and to allow all
    24 bits of the physical X2APIC ID to be used. That patch still needs
    a Signed-off-by from its original author, who once claimed not to
    remember writing it at all. But now we've fixed it, hopefully he'll
    admit it now :)
v5: rebase to v6.1 and remeasure performance, disable parallel bringup
    for AMD CPUs.
v6: rebase to v6.2-rc6, disabled parallel boot on amd as a cpu bug and
    reused timer calibration for secondary CPUs.
v7: [David Woodhouse] iterate over all possible CPUs to find any existing
    cluster mask in alloc_clustermask. (patch 1/9)
    Keep parallel AMD support enabled in AMD, using APIC ID in CPUID leaf
    0x0B (for x2APIC mode) or CPUID leaf 0x01 where 8 bits are sufficient.
    Included sanity checks for APIC id from 0x0B. (patch 6/9)
    Removed patch for reusing timer calibration for secondary CPUs.
    commit message and code improvements.
v8: Fix CPU0 hotplug by setting up the initial_gs, initial_stack and
    early_gdt_descr.
    Drop trampoline lock and bail if APIC ID not found in find_cpunr.
    Code comments improved and debug prints added.
v9: Drop patch to avoid repeated saves of MTRR at boot time.
    rebased and retested at v6.2-rc8.
    added kernel doc for no_parallel_bringup and made do_parallel_bringup
    __ro_after_init.
v10: Fixed suspend/resume not working with parallel smpboot.
     rebased and retested to 6.2.
     fixed checkpatch errors.
v11: Added patches from Brian Gerst to remove the global variables initial_gs,
     initial_stack, and early_gdt_descr from the 64-bit boot code
     (https://lore.kernel.org/all/20230222221301.245890-1-brgerst@gmail.com/).
v12: Fixed compilation errors, acquire tr_lock for every stack setup in
     trampoline_64.S.
     Rearranged commits for a cleaner git history.
v13: Fix build error with CONFIG_FORCE_NR_CPUS.
     Commit message improved, typos fixed and extra comments added.
v14: Enable parallel bringup for SEV-ES guests.
v15: use vendor parallel_smp when platform has CC_ATTR_GUEST_STATE_ENCRYPT.
     Call smpboot_restore_warm_reset_vector incase any of the steps in
     native_cpu_up fail.
     Reset stale stack and kasan unpoison in bringup_cpu
     Release trampoline_lock a bit earlier.
v16: Roll back to CPUHP_OFFLINE on failure in parallel bringup case.
     Release trampoline_lock earlier, just before setup_gdt.
     Rebase to x86/apic (Linux 6.3-rc3).

 
David Woodhouse (8):
  cpu/hotplug: Move idle_thread_get() to <linux/smpboot.h>
  cpu/hotplug: Reset task stack state in _cpu_up()
  cpu/hotplug: Add dynamic parallel bringup states before
    CPUHP_BRINGUP_CPU
  x86/smpboot: Split up native_cpu_up into separate phases and document
    them
  x86/smpboot: Support parallel startup of secondary CPUs
  x86/smpboot: Send INIT/SIPI/SIPI to secondary CPUs in parallel
  x86/smpboot: Serialize topology updates for secondary bringup
  x86/smpboot: Allow parallel bringup for SEV-ES

 .../admin-guide/kernel-parameters.txt         |   3 +
 arch/x86/coco/core.c                          |   5 +
 arch/x86/include/asm/coco.h                   |   1 +
 arch/x86/include/asm/cpu.h                    |   1 +
 arch/x86/include/asm/realmode.h               |   3 +
 arch/x86/include/asm/sev-common.h             |   3 +
 arch/x86/include/asm/smp.h                    |  13 +-
 arch/x86/include/asm/topology.h               |   2 -
 arch/x86/kernel/acpi/sleep.c                  |   9 +-
 arch/x86/kernel/apic/apic.c                   |   2 +-
 arch/x86/kernel/cpu/common.c                  |   6 +-
 arch/x86/kernel/cpu/topology.c                |   3 +-
 arch/x86/kernel/head_64.S                     |  97 +++++
 arch/x86/kernel/smpboot.c                     | 344 +++++++++++++-----
 arch/x86/realmode/init.c                      |   3 +
 arch/x86/realmode/rm/trampoline_64.S          |  27 +-
 arch/x86/xen/smp_pv.c                         |   4 +-
 include/linux/cpuhotplug.h                    |   2 +
 include/linux/smpboot.h                       |   7 +
 kernel/cpu.c                                  |  61 +++-
 kernel/smpboot.h                              |   2 -
 21 files changed, 481 insertions(+), 117 deletions(-)

-- 
2.25.1