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

Usama Arif
2023-03-21T19:41:59Z

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(-)

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2.25.1