>-----Original Message----- >From: Jason Wang <jasow...@redhat.com> >Subject: Re: [PATCH v3 15/17] intel_iommu: Modify x-scalable-mode to be >string option to expose scalable modern mode > >On Fri, Sep 27, 2024 at 2:39 PM Duan, Zhenzhong ><zhenzhong.d...@intel.com> wrote: >> >> >> >> >-----Original Message----- >> >From: Jason Wang <jasow...@redhat.com> >> >Subject: Re: [PATCH v3 15/17] intel_iommu: Modify x-scalable-mode to >be >> >string option to expose scalable modern mode >> > >> >On Wed, Sep 11, 2024 at 1:27 PM Zhenzhong Duan >> ><zhenzhong.d...@intel.com> wrote: >> >> >> >> From: Yi Liu <yi.l....@intel.com> >> >> >> >> Intel VT-d 3.0 introduces scalable mode, and it has a bunch of >capabilities >> >> related to scalable mode translation, thus there are multiple >combinations. >> >> While this vIOMMU implementation wants to simplify it for user by >> >providing >> >> typical combinations. User could config it by "x-scalable-mode" option. >The >> >> usage is as below: >> >> >> >> "-device intel-iommu,x-scalable-mode=["legacy"|"modern"|"off"]" >> >> >> >> - "legacy": gives support for stage-2 page table >> >> - "modern": gives support for stage-1 page table >> >> - "off": no scalable mode support >> >> - any other string, will throw error >> > >> >Those we had "x" prefix but I wonder if this is the best option for >> >enabling scalable-modern mode since the "on" is illegal after this >> >change. >> >> Yes, I was thinking "x" means not stable user interface yet. >> But I do agree with you it's better to keep stable user interface whenever >possible. >> >> > >> >Maybe it's better to just have an "x-fls". Or if we considering the >> >scalable mode is kind of complete, it's time to get rid of "x" prefix. >> >> Ah, I thought this is a question only maintainers and reviewers can decide >if it's complete. >> If no voice on that, I'd like to add "x-fls" as you suggested and keep x- >scalable-mode unchanged. > >A question here: > >Are there any other major features that are still lacking for scalable >mode? If not, maybe we can get rid of the "x" prefix?
We don't support stage-1 and stage-2 coexist emulation and nested translation emulation through stage-1 and stage-2 yet. Currently we only support either stage-1 or stage-2 in scalable mode, one reason is supporting stage1 is enough for current usage, the other reason is to simplify the nesting series https://github.com/yiliu1765/qemu/tree/zhenzhong/iommufd_nesting_rfcv2 for review. Thanks Zhenzhong
