> From: Jason Wang [mailto:jasowang@xxxxxxxxxx] > Sent: Thursday, October 31, 2019 12:33 PM > > > On 2019/10/25 下午6:12, Tian, Kevin wrote: > >> From: Jason Wang [mailto:jasowang@xxxxxxxxxx] > >> Sent: Friday, October 25, 2019 5:49 PM > >> > >> > >> On 2019/10/24 下午8:34, Liu Yi L wrote: > >>> Shared virtual address (SVA), a.k.a, Shared virtual memory (SVM) on > Intel > >>> platforms allow address space sharing between device DMA and > >> applications. > >> > >> > >> Interesting, so the below figure demonstrates the case of VM. I wonder > >> how much differences if we compare it with doing SVM between device > >> and > >> an ordinary process (e.g dpdk)? > >> > >> Thanks > > One difference is that ordinary process requires only stage-1 translation, > > while VM requires nested translation. > > > A silly question, then I believe there's no need for VFIO DMA API in > this case consider the page table is shared between MMU and IOMMU? > yes, only need to intercept guest iotlb invalidation request on stage-1 translation and then forward to IOMMU through new VFIO API. Existing VFIO DMA API applies to only the stage-2 translation (GPA->HPA) here. Thanks Kevin
