• Alex Williamson's avatar
    KVM: Add resampling irqfds for level triggered interrupts · 7a84428a
    Alex Williamson authored
    To emulate level triggered interrupts, add a resample option to
    KVM_IRQFD.  When specified, a new resamplefd is provided that notifies
    the user when the irqchip has been resampled by the VM.  This may, for
    instance, indicate an EOI.  Also in this mode, posting of an interrupt
    through an irqfd only asserts the interrupt.  On resampling, the
    interrupt is automatically de-asserted prior to user notification.
    This enables level triggered interrupts to be posted and re-enabled
    from vfio with no userspace intervention.
    All resampling irqfds can make use of a single irq source ID, so we
    reserve a new one for this interface.
    Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
    Signed-off-by: default avatarAvi Kivity <avi@redhat.com>