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author | Paolo Bonzini <pbonzini@redhat.com> | 2016-03-21 09:15:25 (GMT) |
---|---|---|
committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-03-22 11:02:51 (GMT) |
commit | e9ad4ec8379ad1ba6f68b8ca1c26b50b5ae0a327 (patch) | |
tree | a7116afd39ef9f6758f9b75b6386c8d7d2f0f6eb /virt/kvm | |
parent | 31217db720186edc7ae3c4354e5fa5848bb28358 (diff) | |
download | linux-e9ad4ec8379ad1ba6f68b8ca1c26b50b5ae0a327.tar.xz |
KVM: fix spin_lock_init order on x86
Moving the initialization earlier is needed in 4.6 because
kvm_arch_init_vm is now using mmu_lock, causing lockdep to
complain:
[ 284.440294] INFO: trying to register non-static key.
[ 284.445259] the code is fine but needs lockdep annotation.
[ 284.450736] turning off the locking correctness validator.
...
[ 284.528318] [<ffffffff810aecc3>] lock_acquire+0xd3/0x240
[ 284.533733] [<ffffffffa0305aa0>] ? kvm_page_track_register_notifier+0x20/0x60 [kvm]
[ 284.541467] [<ffffffff81715581>] _raw_spin_lock+0x41/0x80
[ 284.546960] [<ffffffffa0305aa0>] ? kvm_page_track_register_notifier+0x20/0x60 [kvm]
[ 284.554707] [<ffffffffa0305aa0>] kvm_page_track_register_notifier+0x20/0x60 [kvm]
[ 284.562281] [<ffffffffa02ece70>] kvm_mmu_init_vm+0x20/0x30 [kvm]
[ 284.568381] [<ffffffffa02dbf7a>] kvm_arch_init_vm+0x1ea/0x200 [kvm]
[ 284.574740] [<ffffffffa02bff3f>] kvm_dev_ioctl+0xbf/0x4d0 [kvm]
However, it also helps fixing a preexisting problem, which is why this
patch is also good for stable kernels: kvm_create_vm was incrementing
current->mm->mm_count but not decrementing it at the out_err label (in
case kvm_init_mmu_notifier failed). The new initialization order makes
it possible to add the required mmdrop without adding a new error label.
Cc: stable@vger.kernel.org
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt/kvm')
-rw-r--r-- | virt/kvm/kvm_main.c | 21 |
1 files changed, 11 insertions, 10 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 99ee4b1..db021c3 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -536,6 +536,16 @@ static struct kvm *kvm_create_vm(unsigned long type) if (!kvm) return ERR_PTR(-ENOMEM); + spin_lock_init(&kvm->mmu_lock); + atomic_inc(¤t->mm->mm_count); + kvm->mm = current->mm; + kvm_eventfd_init(kvm); + mutex_init(&kvm->lock); + mutex_init(&kvm->irq_lock); + mutex_init(&kvm->slots_lock); + atomic_set(&kvm->users_count, 1); + INIT_LIST_HEAD(&kvm->devices); + r = kvm_arch_init_vm(kvm, type); if (r) goto out_err_no_disable; @@ -568,16 +578,6 @@ static struct kvm *kvm_create_vm(unsigned long type) goto out_err; } - spin_lock_init(&kvm->mmu_lock); - kvm->mm = current->mm; - atomic_inc(&kvm->mm->mm_count); - kvm_eventfd_init(kvm); - mutex_init(&kvm->lock); - mutex_init(&kvm->irq_lock); - mutex_init(&kvm->slots_lock); - atomic_set(&kvm->users_count, 1); - INIT_LIST_HEAD(&kvm->devices); - r = kvm_init_mmu_notifier(kvm); if (r) goto out_err; @@ -602,6 +602,7 @@ out_err_no_disable: for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) kvm_free_memslots(kvm, kvm->memslots[i]); kvm_arch_free_vm(kvm); + mmdrop(current->mm); return ERR_PTR(r); } |