[Bug 210213] New: vCPUs >= 64 can't be online and hotplugged in some scenarios

[Bug 210213] New: vCPUs >= 64 can't be online and hotplugged in some scenarios

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=210213

            Bug ID: 210213
           Summary: vCPUs >= 64 can't be online and hotplugged in some
                    scenarios
           Product: Virtualization
           Version: unspecified
    Kernel Version: 5.10-rc4
          Hardware: x86-64
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: kvm
          Assignee: virtualization_kvm@kernel-bugs.osdl.org
          Reporter: zelin.deng@linux.alibaba.com
        Regression: No

Created attachment 293685
  --> https://bugzilla.kernel.org/attachment.cgi?id=293685&action=edit
Here is a workaround to fix this issue

In VM, if no-kvmclock-vsyscall is set, lscpu shows online 0-63 vcpus are online
vcpus >= 64 are offline and if we attempting to hotplug them, they will return
-ENOMEM.
This issue also happened in VM which are on TSC unstable host.
 bash-14295 [040] .... 64209.953702: cpuhp_enter: cpu: 0064 target: 199 step: 
64 (kvmclock_setup_percpu)
            bash-14295 [040] .... 64209.953702: cpuhp_exit:  cpu: 0064  state: 
64 step:  64 ret: -12
----------------------------

[root@iZwz9208df47apaoyvbmm3Z processor]# cat /sys/kernel/debug/tracing/trace
# tracer: nop
#
# entries-in-buffer/entries-written: 166/166   #P:49
#
#                              _-----=> irqs-off
#                             / _----=> need-resched
#                            | / _---=> hardirq/softirq
#                            || / _--=> preempt-depth
#                            ||| /     delay
#           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
#              | |       |   ||||       |         |
            bash-14295 [040] .... 64209.953675: cpuhp_enter: cpu: 0064 target:
199 step:   1 (smpboot_create_threads)
            bash-14295 [040] .... 64209.953676: cpuhp_exit:  cpu: 0064  state: 
 1 step:   1 ret: 0
            bash-14295 [040] .... 64209.953676: cpuhp_enter: cpu: 0064 target:
199 step:   2 (perf_event_init_cpu)
            bash-14295 [040] .... 64209.953677: cpuhp_exit:  cpu: 0064  state: 
 2 step:   2 ret: 0
            bash-14295 [040] .... 64209.953678: cpuhp_enter: cpu: 0064 target:
199 step:  35 (workqueue_prepare_cpu)
            bash-14295 [040] .... 64209.953678: cpuhp_exit:  cpu: 0064  state: 
35 step:  35 ret: 0
            bash-14295 [040] .... 64209.953678: cpuhp_enter: cpu: 0064 target:
199 step:  37 (hrtimers_prepare_cpu)
            bash-14295 [040] .... 64209.953679: cpuhp_exit:  cpu: 0064  state: 
37 step:  37 ret: 0
            bash-14295 [040] .... 64209.953679: cpuhp_enter: cpu: 0064 target:
199 step:  40 (smpcfd_prepare_cpu)
            bash-14295 [040] .... 64209.953692: cpuhp_exit:  cpu: 0064  state: 
40 step:  40 ret: 0
            bash-14295 [040] .... 64209.953693: cpuhp_enter: cpu: 0064 target:
199 step:  41 (relay_prepare_cpu)
            bash-14295 [040] .... 64209.953693: cpuhp_exit:  cpu: 0064  state: 
41 step:  41 ret: 0
            bash-14295 [040] .... 64209.953693: cpuhp_enter: cpu: 0064 target:
199 step:  44 (rcutree_prepare_cpu)
            bash-14295 [040] .... 64209.953694: cpuhp_exit:  cpu: 0064  state: 
44 step:  44 ret: 0
            bash-14295 [040] .... 64209.953694: cpuhp_enter: cpu: 0064 target:
199 step:  53 (topology_add_dev)
            bash-14295 [040] .... 64209.953699: cpuhp_exit:  cpu: 0064  state: 
53 step:  53 ret: 0
            bash-14295 [040] .... 64209.953700: cpuhp_multi_enter: cpu: 0064
target: 199 step:  56 (trace_rb_cpu_prepare)
            bash-14295 [040] .... 64209.953700: cpuhp_exit:  cpu: 0064  state: 
56 step:  56 ret: 0
            bash-14295 [040] .... 64209.953700: cpuhp_multi_enter: cpu: 0064
target: 199 step:  56 (trace_rb_cpu_prepare)
            bash-14295 [040] .... 64209.953700: cpuhp_exit:  cpu: 0064  state: 
56 step:  56 ret: 0
            bash-14295 [040] .... 64209.953701: cpuhp_multi_enter: cpu: 0064
target: 199 step:  56 (trace_rb_cpu_prepare)
            bash-14295 [040] .... 64209.953701: cpuhp_exit:  cpu: 0064  state: 
56 step:  56 ret: 0
            bash-14295 [040] .... 64209.953701: cpuhp_enter: cpu: 0064 target:
199 step:  62 (timers_prepare_cpu)
            bash-14295 [040] .... 64209.953701: cpuhp_exit:  cpu: 0064  state: 
62 step:  62 ret: 0
            bash-14295 [040] .... 64209.953702: cpuhp_enter: cpu: 0064 target:
199 step:  64 (kvmclock_setup_percpu)
            bash-14295 [040] .... 64209.953702: cpuhp_exit:  cpu: 0064  state: 
64 step:  64 ret: -12

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