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KVM: Drop hack that "manually" informs lockdep of kvm->lock vs. vcpu->mutex

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Now that KVM takes vcpu->mutex inside kvm->lock when creating a vCPU, drop
the hack to manually inform lockdep of the kvm->lock => vcpu->mutex
ordering.

This effectively reverts commit 42a90008f8 ("KVM: Ensure lockdep knows
about kvm->lock vs. vcpu->mutex ordering rule").

Cc: Oliver Upton <oliver.upton@linux.dev>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20241009150455.1057573-7-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2024-10-09 08:04:55 -07:00
parent e53dc37f5a
commit 01528db67f
1 changed files with 2 additions and 7 deletions
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9
virt/kvm/kvm_main.c
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@ -4116,12 +4116,6 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, unsigned long id)
mutex_lock(&kvm->lock); mutex_lock(&kvm->lock);
#ifdef CONFIG_LOCKDEP
/* Ensure that lockdep knows vcpu->mutex is taken *inside* kvm->lock */
mutex_lock(&vcpu->mutex);
mutex_unlock(&vcpu->mutex);
#endif
if (kvm_get_vcpu_by_id(kvm, id)) { if (kvm_get_vcpu_by_id(kvm, id)) {
r = -EEXIST; r = -EEXIST;
goto unlock_vcpu_destroy; goto unlock_vcpu_destroy;
@ -4138,7 +4132,8 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, unsigned long id)
* so that userspace can't invoke vCPU ioctl()s until the vCPU is fully * so that userspace can't invoke vCPU ioctl()s until the vCPU is fully
* visible (per online_vcpus), e.g. so that KVM doesn't get tricked * visible (per online_vcpus), e.g. so that KVM doesn't get tricked
* into a NULL-pointer dereference because KVM thinks the _current_ * into a NULL-pointer dereference because KVM thinks the _current_
* vCPU doesn't exist. * vCPU doesn't exist. As a bonus, taking vcpu->mutex ensures lockdep
* knows it's taken *inside* kvm->lock.
*/ */
mutex_lock(&vcpu->mutex); mutex_lock(&vcpu->mutex);
kvm_get_kvm(kvm); kvm_get_kvm(kvm);