RE: [PATCH v1 0/8] vfio: expose virtual Shared Virtual Addressing to VMs

[Liu, Yi L]

> From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
> Sent: Sunday, March 22, 2020 8:32 PM
> To: alex.williamson@xxxxxxxxxx; eric.auger@xxxxxxxxxx
> Subject: [PATCH v1 0/8] vfio: expose virtual Shared Virtual Addressing to VMs
> 
> From: Liu Yi L <yi.l.liu@xxxxxxxxx>
> 
> 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
> 
> There are roughly four parts in this patchset which are
> corresponding to the basic vSVA support for PCI device
> assignment
>  1. vfio support for PASID allocation and free for VMs
>  2. vfio support for guest page table binding request from VMs
>  3. vfio support for IOMMU cache invalidation from VMs
>  4. vfio support for vSVA usage on IOMMU-backed mdevs
> 
> The complete vSVA kernel upstream patches are divided into three phases:
>     1. Common APIs and PCI device direct assignment
>     2. IOMMU-backed Mediated Device assignment
>     3. Page Request Services (PRS) support
> 
> This patchset is aiming for the phase 1 and phase 2, and based on Jacob's
> below series.
> [PATCH V10 00/11] Nested Shared Virtual Address (SVA) VT-d support:
> https://lkml.org/lkml/2020/3/20/1172
> 
> Complete set for current vSVA can be found in below branch.
> https://github.com/luxis1999/linux-vsva.git: vsva-linux-5.6-rc6
> 
> The corresponding QEMU patch series is as below, complete QEMU set can be
> found in below branch.
> [PATCH v1 00/22] intel_iommu: expose Shared Virtual Addressing to VMs
> complete QEMU set can be found in below link:
> https://github.com/luxis1999/qemu.git: sva_vtd_v10_v1

The ioasid extension is in the below link.

https://lkml.org/lkml/2020/3/25/874

Regards,
Yi Liu