[libvirt] [RFC] Add iommu group commands

Hi, Currently, we need to assign the iommu group to guests manually. It needs to know the groups information. I think we can add some iommu group commands to provide users groups information. I can think of these commands as the following: #virsh group-list <--active> * list all the groups in the system with VFIO * --active: list the active groups which have been used by guests. #virsh group-devs <groupnum> * list the devices in the group. *If groupnum is not specified, it will list every groups' devices. # virsh group-dumpxml <groupnum> * dump the group's xml configuration. dumxml file for example: <iommuGroup number='1'> <address domain='0x0001' bus='0x40' slot='0x00' function='0x0'/> <address domain='0x0001' bus='0x40' slot='0x00' function='0x1'/> </iommuGroup> This information can also be got by #nodedev-dumpxml <device> But users still can't know all the groups and the devices in the group directly. Any suggestions? I want to add iommu symbol to the commands name, but it's too long. Thanks Li Zhang