Add mmu_vcpu_valid_gen for each vcpu

Add mmu_vcpu_valid_gen for each vcpu and change is_obsolete_sp(), if the value
of vcpu->mmu_vcpu_valid_gen added, all the mmu pages related to this vcpu will
be invalic.

Signed-off-by: Arthur Chunqi Li <yzt356@gmail.com>
Optimization of the sync in tm_commit

Keep kicking off vcpus in tm_commit.

Signed-off-by: Arthur Chunqi Li <yzt356@gmail.com>
Add new type unsync preemption

Add a new type of profiling: unsync preemption. This is related to
the unsync model of TM.

Signed-off-by: Arthur Chunqi Li <yzt356@gmail.com>