Re: [PATCH] KVM: arm64: Fix circular locking dependency
From: Oliver Upton
Date: Tue Jan 23 2024 - 12:35:50 EST
On Tue, Jan 23, 2024 at 04:48:19PM +0000, Sebastian Ene wrote:
> The rule inside kvm enforces that the vcpu->mutex is taken *inside*
> kvm->lock. The rule is violated by the pkvm_create_hyp_vm which acquires
^~~~~~~~~~~~~~~~~~
nit: always suffix function names with '()'
> the kvm->lock while already holding the vcpu->mutex lock from
> kvm_vcpu_ioctl. Follow the rule by taking the config lock while getting the
> VM handle and make sure that this is cleaned on VM destroy under the
> same lock.
It is always better to describe a lock in terms of what data it
protects, the critical section(s) are rather obvious here.
Avoid the circular locking dependency altogether by protecting the hyp
vm handle with the config_lock, much like we already do for other
forms of VM-scoped data.
> Signed-off-by: Sebastian Ene <sebastianene@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
nitpicks aside, this looks fine.
Reviewed-by: Oliver Upton <oliver.upton@xxxxxxxxx>
--
Thanks,
Oliver