On 2020/3/30 下午12:24, 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 QEMU 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.
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
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 QEMU patchset is aiming for the phase 1 and phase 2. It is based
on the two kernel series below.
[1] [PATCH V10 00/11] Nested Shared Virtual Address (SVA) VT-d support:
https://lkml.org/lkml/2020/3/20/1172
[2] [PATCH v1 0/8] vfio: expose virtual Shared Virtual Addressing to VMs
https://lkml.org/lkml/2020/3/22/116
There are roughly two parts:
1. Introduce HostIOMMUContext as abstract of host IOMMU. It provides explicit
method for vIOMMU emulators to communicate with host IOMMU. e.g. propagate
guest page table binding to host IOMMU to setup dual-stage DMA translation
in host IOMMU and flush iommu iotlb.
2. Setup dual-stage IOMMU translation for Intel vIOMMU. Includes
- Check IOMMU uAPI version compatibility and VFIO Nesting capabilities which
includes hardware compatibility (stage 1 format) and VFIO_PASID_REQ
availability. This is preparation for setting up dual-stage DMA translation
in host IOMMU.
- Propagate guest PASID allocation and free request to host.
- Propagate guest page table binding to host to setup dual-stage IOMMU DMA
translation in host IOMMU.
- Propagate guest IOMMU cache invalidation to host to ensure iotlb
correctness.
The complete QEMU set can be found in below link:
https://github.com/luxis1999/qemu.git: sva_vtd_v10_v2
Hi Yi:
I could not find the branch there.
Thanks
