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

Liu, Yi L
2020-03-26T12:56:23Z

> From: Liu, Yi L <yi.l.liu@intel.com>
> Sent: Sunday, March 22, 2020 8:32 PM
> To: alex.williamson@redhat.com; eric.auger@redhat.com
> Subject: [PATCH v1 0/8] vfio: expose virtual Shared Virtual Addressing to VMs
>
> From: Liu Yi L <yi.l.liu@intel.com>
>
> 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