KVM: arm64: vgic: Don't acquire its_lock before config_lock
authorOliver Upton <oliver.upton@linux.dev>
Wed, 12 Apr 2023 06:27:33 +0000 (06:27 +0000)
committerMarc Zyngier <maz@kernel.org>
Wed, 12 Apr 2023 12:50:18 +0000 (13:50 +0100)
commit49e5d16b6fc003407a33a9961b4bcbb970bd1c76
treed4ce3d7a2374ae4ec7fa15edcf784b9fda4e0a1e
parentf00327731131d1b5aa6a1aa9f50bcf8d620ace4c
KVM: arm64: vgic: Don't acquire its_lock before config_lock

commit f00327731131 ("KVM: arm64: Use config_lock to protect vgic
state") was meant to rectify a longstanding lock ordering issue in KVM
where the kvm->lock is taken while holding vcpu->mutex. As it so
happens, the aforementioned commit introduced yet another locking issue
by acquiring the its_lock before acquiring the config lock.

This is obviously wrong, especially considering that the lock ordering
is well documented in vgic.c. Reshuffle the locks once more to take the
config_lock before the its_lock. While at it, sprinkle in the lockdep
hinting that has become popular as of late to keep lockdep apprised of
our ordering.

Cc: stable@vger.kernel.org
Fixes: f00327731131 ("KVM: arm64: Use config_lock to protect vgic state")
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230412062733.988229-1-oliver.upton@linux.dev
arch/arm64/kvm/vgic/vgic-its.c