Hi folks,
Running kvm-unit-tests with Linux 5.3.0-rc2 on Kunpeng 920, we will get
the following fail info:
[...]
FAIL psci (4 tests, 1 unexpected failures)
[...]
and
[...]
INFO: unexpected cpu_on return value: caller=CPU9, ret=-2
FAIL: cpu-on
SUMMARY: 4 tests, 1 unexpected failures
I think this is an issue had been fixed once by commit 6c7a5dce22b3
("KVM: arm/arm64: fix races in kvm_psci_vcpu_on"), which makes use of
kvm->lock mutex to fix the race between two PSCI_CPU_ON calls - one
does reset on the MPIDR register whilst another reads it.
But commit 358b28f09f0 ("arm/arm64: KVM: Allow a VCPU to fully reset
itself") later moves the reset work into check_vcpu_requests(), by
making a KVM_REQ_VCPU_RESET request in PSCI code. Thus the reset work
has not been protected by kvm->lock mutex anymore, and the race shows up
again...
Do we need a fix for this issue? At least achieve a mutex execution
between the reset of MPIDR and kvm_mpidr_to_vcpu()?
Thanks,
zenghui
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