• Alex Williamson's avatar
    vfio/pci: Add ioeventfd support · 30656177
    Alex Williamson authored
    The ioeventfd here is actually irqfd handling of an ioeventfd such as
    supported in KVM.  A user is able to pre-program a device write to
    occur when the eventfd triggers.  This is yet another instance of
    eventfd-irqfd triggering between KVM and vfio.  The impetus for this
    is high frequency writes to pages which are virtualized in QEMU.
    Enabling this near-direct write path for selected registers within
    the virtualized page can improve performance and reduce overhead.
    Specifically this is initially targeted at NVIDIA graphics cards where
    the driver issues a write to an MMIO register within a virtualized
    region in order to allow the MSI interrupt to re-trigger.
    Reviewed-by: default avatarPeter Xu <peterx@redhat.com>
    Reviewed-by: default avatarAlexey Kardashevskiy <aik@ozlabs.ru>
    Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
    30656177
vfio_pci_rdwr.c 8.25 KB