> From: Jason Wang <jasowang@xxxxxxxxxx> > Sent: Monday, September 14, 2020 12:20 PM > > On 2020/9/10 下午6:45, Liu Yi L wrote: > > Shared Virtual Addressing (SVA), a.k.a, Shared Virtual Memory (SVM) on > > Intel platforms allows address space sharing between device DMA and > > applications. SVA can reduce programming complexity and enhance > security. > > > > This VFIO series is intended to expose SVA usage to VMs. i.e. Sharing > > guest application address space with passthru devices. This is called > > vSVA in this series. The whole vSVA enabling requires QEMU/VFIO/IOMMU > > changes. For IOMMU and QEMU changes, they are in separate series (listed > > in the "Related series"). > > > > The high-level architecture for SVA virtualization is as below, the key > > design of vSVA support is to utilize the dual-stage IOMMU translation ( > > also known as IOMMU nesting translation) capability in host IOMMU. > > > > > > .-------------. .---------------------------. > > | vIOMMU | | Guest process CR3, FL only| > > | | '---------------------------' > > .----------------/ > > | PASID Entry |--- PASID cache flush - > > '-------------' | > > | | V > > | | CR3 in GPA > > '-------------' > > Guest > > ------| Shadow |--------------------------|-------- > > v v v > > Host > > .-------------. .----------------------. > > | pIOMMU | | Bind FL for GVA-GPA | > > | | '----------------------' > > .----------------/ | > > | PASID Entry | V (Nested xlate) > > '----------------\.------------------------------. > > | ||SL for GPA-HPA, default domain| > > | | '------------------------------' > > '-------------' > > Where: > > - FL = First level/stage one page tables > > - SL = Second level/stage two page tables > > > > Patch Overview: > > 1. reports IOMMU nesting info to userspace ( patch 0001, 0002, 0003, > 0015 , 0016) > > 2. vfio support for PASID allocation and free for VMs (patch 0004, 0005, > 0007) > > 3. a fix to a revisit in intel iommu driver (patch 0006) > > 4. vfio support for binding guest page table to host (patch 0008, 0009, > 0010) > > 5. vfio support for IOMMU cache invalidation from VMs (patch 0011) > > 6. vfio support for vSVA usage on IOMMU-backed mdevs (patch 0012) > > 7. expose PASID capability to VM (patch 0013) > > 8. add doc for VFIO dual stage control (patch 0014) > > > If it's possible, I would suggest a generic uAPI instead of a VFIO > specific one. > > Jason suggest something like /dev/sva. There will be a lot of other > subsystems that could benefit from this (e.g vDPA). > Just be curious. When does vDPA subsystem plan to support vSVA and when could one expect a SVA-capable vDPA device in market? Thanks Kevin
