When new MSI-X vectors are enabled we need to disable MSI-X and
re-enable it with the correct number of vectors. That means we need
to reprogram the eventfd triggers for each vector. Prior to f4d45d47
vector->use tracked whether a vector was masked or unmasked and we
could always pick the KVM path when available for unmasked vectors.
Now vfio doesn't track mask state itself and vector->use and virq
remains configured even for masked vectors. Therefore we need to ask
the MSI-X code whether a vector is masked in order to select the
correct signaling path. As noted in the comment, MSI relies on
hardware to handle masking.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Cc: qemu-stable@nongnu.org # QEMU 2.1
c048be5cc9