On Wed, Nov 13, 2024 at 07:18:42PM -0800, Nicolin Chen wrote: > > so the user would try to create vDevices with a given viommu_obj until > > failure, then it would allocate another viommu_obj for the failed device. > > is it? sounds reasonable. > > Yes. It is the same as previously dealing with a nesting parent: > test and allocate if fails. The virtual IOMMU driver in VMM can > keep a list of the vIOMMU objects for each device to test. The viommu object should be tied to the VMM's vIOMMU vHW object that it is paravirtualizing toward the VM. So we shouldn't be creating viommu objects on demand, it should be created when the vIOMMU is created, and the presumably the qemu command line will describe how to link vPCI/VFIO functions to vIOMMU instances. If they kernel won't allow the user's configuration then it should fail, IMHO. Some try-and-fail might be interesting to auto-provision vIOMMU's and provision vPCI functions. Though I suspect we will be providing information in other ioctls so something like libvirt can construct the correct configuration directly. Jason
