UPSTREAM: kvm: don't try to register to KVM_FAST_MMIO_BUS for non mmio eventfd

[ Upstream commit 8453fecbecae26edb3f278627376caab05d9a88d ]

We only want zero length mmio eventfd to be registered on
KVM_FAST_MMIO_BUS. So check this explicitly when arg->len is zero to
make sure this.

BUG=chromium:846515
TEST=build/boot on hana with USE=kvm_host

Change-Id: I419261d4ae576fcbef443e220e4266cf4cd839b6
Cc: stable@vger.kernel.org
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
(cherry picked from commit d758df24a58e5160270c74b467dfa6453fceb91b
 in https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/)
Signed-off-by: Sonny Rao <sonnyrao@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1088094
1 file changed