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authorPaolo Bonzini <pbonzini@redhat.com>2016-03-21 10:15:25 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-04-12 09:08:34 -0700
commit4e2fa4bbbac1c2e198e4c980d451c9ec568ae798 (patch)
treebc50b66b49525fba5fe27cb47ab9807e2271f8ad /virt
parent49f0cbfc3e73108c319c3d3cc5fe04587d96b654 (diff)
downloadlinux-linaro-stable-4e2fa4bbbac1c2e198e4c980d451c9ec568ae798.tar.gz
KVM: fix spin_lock_init order on x86
commit e9ad4ec8379ad1ba6f68b8ca1c26b50b5ae0a327 upstream. 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. Reported-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/kvm_main.c21
1 files changed, 11 insertions, 10 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 7338e30421d8..fefbf2d148ef 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -547,6 +547,16 @@ static struct kvm *kvm_create_vm(unsigned long type)
if (!kvm)
return ERR_PTR(-ENOMEM);
+ spin_lock_init(&kvm->mmu_lock);
+ atomic_inc(&current->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;
@@ -579,16 +589,6 @@ 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;
@@ -613,6 +613,7 @@ 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);
}