On 17.03.24 09:37, Keqian Zhu via wrote:
For vCPU being hotplugged, qemu_init_vcpu() is called. In this
function, we set vcpu state as stopped, and then wait vcpu thread
to be created.
As the vcpu state is stopped, it will inform us it has been created
and then wait on halt_cond. After we has realized vcpu object, we
will resume the vcpu thread.
However, during we wait vcpu thread to be created, the bql is
unlocked, and other thread is allowed to call resume_all_vcpus(),
which will resume the un-realized vcpu.
This fixes the issue by filter out un-realized vcpu during
resume_all_vcpus().
Similar question: is there a reproducer?
How could we currently hotplug a VCPU, and while it is being created,
see pause_all_vcpus()/resume_all_vcpus() getting claled.
If I am not getting this wrong, there seems to be some other mechanism
missing that makes sure that this cannot happen. Dropping the BQL
half-way through creating a VCPU might be the problem.
--
Cheers,
David / dhildenb
