Messages in this thread | | | Date | Wed, 27 Jun 2012 13:20:24 +0300 | From | "Michael S. Tsirkin" <> | Subject | Re: [PATCH] kvm: don't clear level from irqfd |
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On Wed, Jun 27, 2012 at 01:03:46PM +0300, Gleb Natapov wrote: > On Wed, Jun 27, 2012 at 12:13:43PM +0300, Michael S. Tsirkin wrote: > > irqfd sets and clears the level immediately. > > This used to be necessary for MSI interrupts but isn't anymore. > > > > Note! We never officially supported irqfd for level > > interrupts but it usually seemed to kind of work, > > and this change will break it. There are no known > > real users of that feature though - only old vfio prototypes. > > Removing this line will make it easier to add > > real support for level irqfds in the future. > > > Did we officially supported irqfd for ioapic/pic edge interrupts? > Because those will break to.
Hard to say - as Alex points out it was never documented. But at least they actually worked reliably. Hmm. One way to address this is to add kvm_trigger_irq which will trigger edge interrupts unconditionally.
Not sure it's worth it though.
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > > --- > > virt/kvm/eventfd.c | 1 - > > 1 file changed, 1 deletion(-) > > > > diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c > > index f59c1e8..4db6b01 100644 > > --- a/virt/kvm/eventfd.c > > +++ b/virt/kvm/eventfd.c > > @@ -68,7 +68,6 @@ irqfd_inject(struct work_struct *work) > > struct kvm *kvm = irqfd->kvm; > > > > kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1); > > - kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0); > > } > > > > /* > > -- > > MST > > -- > Gleb.
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