On 04/20/2010 06:54 PM, Marcelo Tosatti wrote:
The assigned device interrupt work handler calls kvm_set_irq, which
can sleep, for example, waiting for the ioapic mutex, from irq disabled
section.
https://bugzilla.kernel.org/show_bug.cgi?id=15725
Fix by dropping assigned_dev_lock (and re-enabling interrupts)
before invoking kvm_set_irq for the KVM_DEV_IRQ_HOST_MSIX case. Other
cases do not require the lock or interrupts disabled (a new work
instance will be queued in case of concurrent interrupt).
KVM-Stable-Tag.
Signed-off-by: Marcelo Tosatti<mtosa...@redhat.com>
diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
index 47ca447..7ac7bbe 100644
--- a/virt/kvm/assigned-dev.c
+++ b/virt/kvm/assigned-dev.c
@@ -64,24 +64,33 @@ static void kvm_assigned_dev_interrupt_work_handler(struct
work_struct *work)
interrupt_work);
kvm = assigned_dev->kvm;
- spin_lock_irq(&assigned_dev->assigned_dev_lock);
if (assigned_dev->irq_requested_type& KVM_DEV_IRQ_HOST_MSIX) {
struct kvm_guest_msix_entry *guest_entries =
assigned_dev->guest_msix_entries;
+
+ spin_lock_irq(&assigned_dev->assigned_dev_lock);
for (i = 0; i< assigned_dev->entries_nr; i++) {
if (!(guest_entries[i].flags&
KVM_ASSIGNED_MSIX_PENDING))
continue;
guest_entries[i].flags&= ~KVM_ASSIGNED_MSIX_PENDING;
+ /*
+ * If kvm_assigned_dev_intr sets pending for an
+ * entry smaller than this work instance is
+ * currently processing, a new work instance
+ * will be queued.
+ */
+ spin_unlock_irq(&assigned_dev->assigned_dev_lock);
What happens if assigned_dev->entries_nr is changed here?
kvm_set_irq(assigned_dev->kvm,
assigned_dev->irq_source_id,
guest_entries[i].vector, 1);
+ spin_lock_irq(&assigned_dev->assigned_dev_lock);
}
+ spin_unlock_irq(&assigned_dev->assigned_dev_lock);
} else
kvm_set_irq(assigned_dev->kvm, assigned_dev->irq_source_id,
assigned_dev->guest_irq, 1);
- spin_unlock_irq(&assigned_dev->assigned_dev_lock);
}
A less dangerous fix is to copy all vectors to be triggered into a local
array, drop the lock, and replay the array into kvm_set_irq(). The else
branch could do this as well.
--
error compiling committee.c: too many arguments to function
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