diff options
| author | Oliver Upton <oliver.upton@linux.dev> | 2023-04-12 06:27:33 +0000 |
|---|---|---|
| committer | Marc Zyngier <maz@kernel.org> | 2023-04-12 13:50:18 +0100 |
| commit | 49e5d16b6fc003407a33a9961b4bcbb970bd1c76 (patch) | |
| tree | d4ce3d7a2374ae4ec7fa15edcf784b9fda4e0a1e /arch/arm64/kvm | |
| parent | f00327731131d1b5aa6a1aa9f50bcf8d620ace4c (diff) | |
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
Diffstat (limited to 'arch/arm64/kvm')
| -rw-r--r-- | arch/arm64/kvm/vgic/vgic-its.c | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c index 7713cd06104e..750e51e3779a 100644 --- a/arch/arm64/kvm/vgic/vgic-its.c +++ b/arch/arm64/kvm/vgic/vgic-its.c @@ -1958,6 +1958,16 @@ static int vgic_its_create(struct kvm_device *dev, u32 type) mutex_init(&its->its_lock); mutex_init(&its->cmd_lock); + /* Yep, even more trickery for lock ordering... */ +#ifdef CONFIG_LOCKDEP + mutex_lock(&dev->kvm->arch.config_lock); + mutex_lock(&its->cmd_lock); + mutex_lock(&its->its_lock); + mutex_unlock(&its->its_lock); + mutex_unlock(&its->cmd_lock); + mutex_unlock(&dev->kvm->arch.config_lock); +#endif + its->vgic_its_base = VGIC_ADDR_UNDEF; INIT_LIST_HEAD(&its->device_list); @@ -2752,15 +2762,14 @@ static int vgic_its_ctrl(struct kvm *kvm, struct vgic_its *its, u64 attr) return 0; mutex_lock(&kvm->lock); - mutex_lock(&its->its_lock); if (!lock_all_vcpus(kvm)) { - mutex_unlock(&its->its_lock); mutex_unlock(&kvm->lock); return -EBUSY; } mutex_lock(&kvm->arch.config_lock); + mutex_lock(&its->its_lock); switch (attr) { case KVM_DEV_ARM_ITS_CTRL_RESET: @@ -2774,9 +2783,9 @@ static int vgic_its_ctrl(struct kvm *kvm, struct vgic_its *its, u64 attr) break; } + mutex_unlock(&its->its_lock); mutex_unlock(&kvm->arch.config_lock); unlock_all_vcpus(kvm); - mutex_unlock(&its->its_lock); mutex_unlock(&kvm->lock); return ret; } |