Commit 74b5c5bf authored Jun 03, 2011 by Mike Waychison Committed by Avi Kivity Jun 06, 2011

KVM: Initialize kvm before registering the mmu notifier



It doesn't make sense to ever see a half-initialized kvm structure on
mmu notifier callbacks.  Previously, 85722cda changed the ordering to
ensure that the mmu_lock was initialized before mmu notifier
registration, but there is still a race where the mmu notifier could
come in and try accessing other portions of struct kvm before they are
intialized.

Solve this by moving the mmu notifier registration to occur after the
structure is completely initialized.

Google-Bug-Id: 452199
Signed-off-by: Mike Waychison <mikew@google.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

parent 221192bd

virt/kvm/kvm_main.c

+6 −5

Original line number	Diff line number	Diff line
		@@ -467,12 +467,8 @@ static struct kvm *kvm_create_vm(void)
		if (!kvm->buses[i])
		goto out_err;
		}
		spin_lock_init(&kvm->mmu_lock);

		r = kvm_init_mmu_notifier(kvm);
		if (r)
		goto out_err;

		spin_lock_init(&kvm->mmu_lock);
		kvm->mm = current->mm;
		atomic_inc(&kvm->mm->mm_count);
		kvm_eventfd_init(kvm);
		@@ -480,6 +476,11 @@ static struct kvm *kvm_create_vm(void)
		mutex_init(&kvm->irq_lock);
		mutex_init(&kvm->slots_lock);
		atomic_set(&kvm->users_count, 1);

		r = kvm_init_mmu_notifier(kvm);
		if (r)
		goto out_err;

		raw_spin_lock(&kvm_lock);
		list_add(&kvm->vm_list, &vm_list);
		raw_spin_unlock(&kvm_lock);

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