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KVM: fix OOPS on flush_work

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The conversion done by commit 3706feacd0 ("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: 3706feacd0
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2016-10-26 13:35:56 +02:00
parent e1e575f6b0
commit 36343f6ea7
2 changed files with 25 additions and 3 deletions
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22
virt/kvm/eventfd.c
View File

@ -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

6
virt/kvm/kvm_main.c
View File

@ -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 @@ out_free_0a:
free_cpumask_var(cpus_hardware_enabled);
out_free_0:
kvm_irqfd_exit();
out_irqfd:
kvm_arch_exit();
out_fail:
return r;