Re: [RFC v2 00/22] intel_iommu: expose Shared Virtual Addressing to VM

[Jason Wang <jasowang@redhat.com>]

On 2019/10/24 下午8:34, Liu Yi L wrote:
> Shared virtual address (SVA), a.k.a, Shared virtual memory (SVM) on Intel
> platforms allow address space sharing between device DMA and applications.


Interesting, so the below figure demonstrates the case of VM. I wonder 
how much differences if we compare it with doing SVM between device and 
an ordinary process (e.g dpdk)?

Thanks


> SVA can reduce programming complexity and enhance security.
> This series is intended to expose SVA capability to VMs. i.e. shared guest
> application address space with passthru devices. The whole SVA virtualization
> requires QEMU/VFIO/IOMMU changes. This series includes the QEMU changes, for
> VFIO and IOMMU changes, they are in separate series (listed in the "Related
> series").
>
> The high-level architecture for SVA virtualization is as below:
>
>      .-------------.  .---------------------------.
>      |   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 upstream patches are divided into three phases:
>      1. Common APIs and PCI device direct assignment
>      2. Page Request Services (PRS) support
>      3. Mediated device assignment
>
> This RFC patchset is aiming for the phase 1. Works together with the VT-d
> driver[1] changes and VFIO changes[2].
>
> Related series:
> [1] [PATCH v6 00/10] Nested Shared Virtual Address (SVA) VT-d support:
> https://lkml.org/lkml/2019/10/22/953
> <This series is based on this kernel series from Jacob Pan>
>
> [2] [RFC v2 0/3] vfio: support Shared Virtual Addressing from Yi Liu
>
> There are roughly four parts:
>   1. Introduce IOMMUContext as abstract layer between vIOMMU emulator and
>      VFIO to avoid direct calling between the two
>   2. Passdown PASID allocation and free to host
>   3. Passdown guest PASID binding to host
>   4. Passdown guest IOMMU cache invalidation to host
>
> The full set can be found in below link:
> https://github.com/luxis1999/qemu.git: sva_vtd_v6_qemu_rfc_v2
>
> Changelog:
> 	- RFC v1 -> v2:
> 	  Introduce IOMMUContext to abstract the connection between VFIO
> 	  and vIOMMU emulator, which is a replacement of the PCIPASIDOps
> 	  in RFC v1. Modify x-scalable-mode to be string option instead of
> 	  adding a new option as RFC v1 did. Refined the pasid cache management
> 	  and addressed the TODOs mentioned in RFC v1.
> 	  RFC v1: https://patchwork.kernel.org/cover/11033657/
>
> Eric Auger (1):
>    update-linux-headers: Import iommu.h
>
> Liu Yi L (20):
>    header update VFIO/IOMMU vSVA APIs against 5.4.0-rc3+
>    intel_iommu: modify x-scalable-mode to be string option
>    vfio/common: add iommu_ctx_notifier in container
>    hw/pci: modify pci_setup_iommu() to set PCIIOMMUOps
>    hw/pci: introduce pci_device_iommu_context()
>    intel_iommu: provide get_iommu_context() callback
>    vfio/pci: add iommu_context notifier for pasid alloc/free
>    intel_iommu: add virtual command capability support
>    intel_iommu: process pasid cache invalidation
>    intel_iommu: add present bit check for pasid table entries
>    intel_iommu: add PASID cache management infrastructure
>    vfio/pci: add iommu_context notifier for pasid bind/unbind
>    intel_iommu: bind/unbind guest page table to host
>    intel_iommu: replay guest pasid bindings to host
>    intel_iommu: replay pasid binds after context cache invalidation
>    intel_iommu: do not passdown pasid bind for PASID #0
>    vfio/pci: add iommu_context notifier for PASID-based iotlb flush
>    intel_iommu: process PASID-based iotlb invalidation
>    intel_iommu: propagate PASID-based iotlb invalidation to host
>    intel_iommu: process PASID-based Device-TLB invalidation
>
> Peter Xu (1):
>    hw/iommu: introduce IOMMUContext
>
>   hw/Makefile.objs                |    1 +
>   hw/alpha/typhoon.c              |    6 +-
>   hw/arm/smmu-common.c            |    6 +-
>   hw/hppa/dino.c                  |    6 +-
>   hw/i386/amd_iommu.c             |    6 +-
>   hw/i386/intel_iommu.c           | 1249 +++++++++++++++++++++++++++++++++++++--
>   hw/i386/intel_iommu_internal.h  |  109 ++++
>   hw/i386/trace-events            |    6 +
>   hw/iommu/Makefile.objs          |    1 +
>   hw/iommu/iommu.c                |   66 +++
>   hw/pci-host/designware.c        |    6 +-
>   hw/pci-host/ppce500.c           |    6 +-
>   hw/pci-host/prep.c              |    6 +-
>   hw/pci-host/sabre.c             |    6 +-
>   hw/pci/pci.c                    |   27 +-
>   hw/ppc/ppc440_pcix.c            |    6 +-
>   hw/ppc/spapr_pci.c              |    6 +-
>   hw/s390x/s390-pci-bus.c         |    8 +-
>   hw/vfio/common.c                |   10 +
>   hw/vfio/pci.c                   |  149 +++++
>   include/hw/i386/intel_iommu.h   |   58 +-
>   include/hw/iommu/iommu.h        |  113 ++++
>   include/hw/pci/pci.h            |   13 +-
>   include/hw/pci/pci_bus.h        |    2 +-
>   include/hw/vfio/vfio-common.h   |    9 +
>   linux-headers/linux/iommu.h     |  324 ++++++++++
>   linux-headers/linux/vfio.h      |   83 +++
>   scripts/update-linux-headers.sh |    2 +-
>   28 files changed, 2232 insertions(+), 58 deletions(-)
>   create mode 100644 hw/iommu/Makefile.objs
>   create mode 100644 hw/iommu/iommu.c
>   create mode 100644 include/hw/iommu/iommu.h
>   create mode 100644 linux-headers/linux/iommu.h
>