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

Liu, Yi L
2020-03-22T12:26:53Z

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

Regards,
Yi Liu

Changelog:
- RFC v1 -> Patch v1:
a) Address comments to the PASID request(alloc/free) path
b) Report PASID alloc/free availabitiy to user-space
c) Add a vfio_iommu_type1 parameter to support pasid quota tuning
d) Adjusted to latest ioasid code implementation. e.g. remove the
code for tracking the allocated PASIDs as latest ioasid code
will track it, VFIO could use ioasid_free_set() to free all
PASIDs.

- RFC v2 -> v3:
a) Refine the whole patchset to fit the roughly parts in this series
b) Adds complete vfio PASID management framework. e.g. pasid alloc,
free, reclaim in VM crash/down and per-VM PASID quota to prevent
PASID abuse.
c) Adds IOMMU uAPI version check and page table format check to ensure
version compatibility and hardware compatibility.
d) Adds vSVA vfio support for IOMMU-backed mdevs.

- RFC v1 -> v2:
Dropped vfio: VFIO_IOMMU_ATTACH/DETACH_PASID_TABLE.

Liu Yi L (8):
vfio: Add VFIO_IOMMU_PASID_REQUEST(alloc/free)
vfio/type1: Add vfio_iommu_type1 parameter for quota tuning
vfio/type1: Report PASID alloc/free support to userspace
vfio: Check nesting iommu uAPI version
vfio/type1: Report 1st-level/stage-1 format to userspace
vfio/type1: Bind guest page tables to host
vfio/type1: Add VFIO_IOMMU_CACHE_INVALIDATE
vfio/type1: Add vSVA support for IOMMU-backed mdevs

drivers/vfio/vfio.c | 136 +++++++++++++
drivers/vfio/vfio_iommu_type1.c | 419 ++++++++++++++++++++++++++++++++++++++++
include/linux/vfio.h | 21 ++
include/uapi/linux/vfio.h | 127 ++++++++++++
4 files changed, 703 insertions(+)

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2.7.4