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Commit 36343f6e authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

KVM: fix OOPS on flush_work 



The conversion done by commit 3706feac ("KVM: Remove deprecated
create_singlethread_workqueue") is broken.  It flushes a single work
item &irqfd->shutdown instead of all of them, and even worse if there
is no irqfd on the list then you get a NULL pointer dereference.
Revert the virt/kvm/eventfd.c part of that patch; to avoid the
deprecated function, just allocate our own workqueue---it does
not even have to be unbound---with alloc_workqueue.

Fixes: 3706feac
Reviewed-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent e1e575f6

virt/kvm/eventfd.c

+19 −3
Original line number Diff line number Diff line
@@ -42,6 +42,7 @@ 


#ifdef CONFIG_HAVE_KVM_IRQFD



static struct workqueue_struct *irqfd_cleanup_wq;



static void

irqfd_inject(struct work_struct *work)
@@ -167,7 +168,7 @@ irqfd_deactivate(struct kvm_kernel_irqfd *irqfd) 


	list_del_init(&irqfd->list);



	schedule_work(&irqfd->shutdown);

	queue_work(irqfd_cleanup_wq, &irqfd->shutdown);

}



int __attribute__((weak)) kvm_arch_set_irq_inatomic(
@@ -554,7 +555,7 @@ kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args) 
	 * so that we guarantee there will not be any more interrupts on this

	 * gsi once this deassign function returns.

	 */

	flush_work(&irqfd->shutdown);

	flush_workqueue(irqfd_cleanup_wq);



	return 0;

}
@@ -591,7 +592,7 @@ kvm_irqfd_release(struct kvm *kvm) 
	 * Block until we know all outstanding shutdown jobs have completed

	 * since we do not take a kvm* reference.

	 */

	flush_work(&irqfd->shutdown);

	flush_workqueue(irqfd_cleanup_wq);



}
@@ -621,8 +622,23 @@ void kvm_irq_routing_update(struct kvm *kvm) 
	spin_unlock_irq(&kvm->irqfds.lock);

}



/*

 * create a host-wide workqueue for issuing deferred shutdown requests

 * aggregated from all vm* instances. We need our own isolated

 * queue to ease flushing work items when a VM exits.

 */

int kvm_irqfd_init(void)

{

	irqfd_cleanup_wq = alloc_workqueue("kvm-irqfd-cleanup", 0, 0);

	if (!irqfd_cleanup_wq)

		return -ENOMEM;



	return 0;

}



void kvm_irqfd_exit(void)

{

	destroy_workqueue(irqfd_cleanup_wq);

}

#endif

virt/kvm/kvm_main.c

+6 −0
Original line number Diff line number Diff line
@@ -3846,7 +3846,12 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, 
	 * kvm_arch_init makes sure there's at most one caller

	 * for architectures that support multiple implementations,

	 * like intel and amd on x86.

	 * kvm_arch_init must be called before kvm_irqfd_init to avoid creating

	 * conflicts in case kvm is already setup for another implementation.

	 */

	r = kvm_irqfd_init();

	if (r)

		goto out_irqfd;



	if (!zalloc_cpumask_var(&cpus_hardware_enabled, GFP_KERNEL)) {

		r = -ENOMEM;
@@ -3928,6 +3933,7 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, 
	free_cpumask_var(cpus_hardware_enabled);

out_free_0:

	kvm_irqfd_exit();

out_irqfd:

	kvm_arch_exit();

out_fail:

	return r;