> -----Original Message----- > From: Jason Wang [mailto:jasow...@redhat.com] > Sent: Thursday, February 16, 2017 1:44 PM > To: Liu, Yi L <yi.l....@intel.com>; Michael S. Tsirkin <m...@redhat.com>; > qemu- > de...@nongnu.org > Cc: Peter Maydell <peter.mayd...@linaro.org>; Eduardo Habkost > <ehabk...@redhat.com>; Peter Xu <pet...@redhat.com>; Paolo Bonzini > <pbonz...@redhat.com>; Richard Henderson <r...@twiddle.net>; Tian, Kevin > <kevin.t...@intel.com>; Lan, Tianyu <tianyu....@intel.com>; Alex Williamson > <alex.william...@redhat.com> > Subject: Re: [Qemu-devel] [PULL 08/41] intel_iommu: support device iotlb > descriptor > > > > On 2017年02月16日 13:36, Liu, Yi L wrote: > >> -----Original Message----- > >> From: Qemu-devel > >> [mailto:qemu-devel-bounces+yi.l.liu=intel....@nongnu.org] > >> On Behalf Of Michael S. Tsirkin > >> Sent: Tuesday, January 10, 2017 1:40 PM > >> To: qemu-devel@nongnu.org > >> Cc: Peter Maydell <peter.mayd...@linaro.org>; Eduardo Habkost > >> <ehabk...@redhat.com>; Jason Wang <jasow...@redhat.com>; Peter Xu > >> <pet...@redhat.com>; Paolo Bonzini <pbonz...@redhat.com>; Richard > >> Henderson <r...@twiddle.net> > >> Subject: [Qemu-devel] [PULL 08/41] intel_iommu: support device iotlb > >> descriptor > >> > >> From: Jason Wang <jasow...@redhat.com> > >> > >> This patch enables device IOTLB support for intel iommu. The major > >> work is to implement QI device IOTLB descriptor processing and notify > >> the device through iommu notifier. > >> > > Hi Jason/Michael, > > > > Recently Peter Xu's patch also touched intel-iommu emulation. His > > patch shadows second-level page table by capturing iotlb flush from > > guest. It would result in page table updating in host. Does this patch > > also use the same map/umap API provided by VFIO? > > Yes, it depends on the iommu notifier too. > > > If it is, then I think it would also update page table in host. It > > looks to be a duplicate update. Pls refer to the following snapshot > > captured from section 6.5.2.5 of vtd spec. > > > > "Since translation requests from a device may be serviced by hardware > > from the IOTLB, software must always request IOTLB invalidation > > (iotlb_inv_dsc) before requesting corresponding Device-TLB > > (dev_tlb_inv_dsc) invalidation." > > > > Maybe for device-iotlb, we need a separate API which just pass down > > the invalidate info without updating page table. Any thoughts? > > cc Alex. > > If we want ATS to be visible for guest (but I'm not sure if VFIO support > this), we > probably need another notifier or a new flag.
Jason, for assigned device, I think guest could see ATS if the assigned device supports ATS. I can see it when passthru iGPU. Regards, Yi L