UPSTREAM: kvm: factor out core eventfd assign/deassign logic

[ Upstream commit 85da11ca587c8eb73993a1b503052391a73586f9 ]

This patch factors out core eventfd assign/deassign logic and leaves
the argument checking and bus index selection to callers.

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

Change-Id: I193d122f44b025b26ae8e5f838b1ecfdabb473a0
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 7642b3f109228718f1bf57c35210c9a36696a465
 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/1088095
1 file changed