[RFC,XEN,v3,0/5] IOMMU subsystem redesign and PV-IOMMU interface

Message

Teddy Astie July 11, 2024, 2:04 p.m. UTC

This work has been presented at Xen Summit 2024 during the
  IOMMU paravirtualization and Xen IOMMU subsystem rework
design session.

Operating systems may want to have access to a IOMMU in order to do DMA
protection or implement certain features (e.g VFIO on Linux).

VFIO support is mandatory for framework such as SPDK, which can be useful to
implement an alternative storage backend for virtual machines [1].

In this patch series, we introduce in Xen the ability to manage several
contexts per domain and provide a new hypercall interface to allow guests
to manage IOMMU contexts.

The VT-d driver is updated to support these new features.

[1] Using SPDK with the Xen hypervisor - FOSDEM 2023

---
Changed in v2 :
* fixed Xen crash when dumping IOMMU contexts (using X debug key)
with DomUs without IOMMU
* s/dettach/detach/
* removed some unused includes
* fix dangling devices in contexts with detach

Changed in v3 :
* lock entirely map/unmap in hypercall
* prevent IOMMU operations on dying contexts (fix race condition)
* iommu_check_context+iommu_get_context -> iommu_get_context and check for NULL

Teddy Astie (5):
  docs/designs: Add a design document for PV-IOMMU
  docs/designs: Add a design document for IOMMU subsystem redesign
  IOMMU: Introduce redesigned IOMMU subsystem
  VT-d: Port IOMMU driver to new subsystem
  xen/public: Introduce PV-IOMMU hypercall interface
---

 docs/designs/iommu-contexts.md       |  398 +++++++
 docs/designs/pv-iommu.md             |  105 ++
 xen/arch/x86/domain.c                |    2 +-
 xen/arch/x86/include/asm/arena.h     |   54 +
 xen/arch/x86/include/asm/iommu.h     |   44 +-
 xen/arch/x86/include/asm/pci.h       |   17 -
 xen/arch/x86/mm/p2m-ept.c            |    2 +-
 xen/arch/x86/pv/dom0_build.c         |    4 +-
 xen/arch/x86/tboot.c                 |    4 +-
 xen/common/Makefile                  |    1 +
 xen/common/memory.c                  |    4 +-
 xen/common/pv-iommu.c                |  328 ++++++
 xen/drivers/passthrough/Kconfig      |   14 +
 xen/drivers/passthrough/Makefile     |    3 +
 xen/drivers/passthrough/context.c    |  649 +++++++++++
 xen/drivers/passthrough/iommu.c      |  337 ++----
 xen/drivers/passthrough/pci.c        |   49 +-
 xen/drivers/passthrough/quarantine.c |   49 +
 xen/drivers/passthrough/vtd/Makefile |    2 +-
 xen/drivers/passthrough/vtd/extern.h |   14 +-
 xen/drivers/passthrough/vtd/iommu.c  | 1557 +++++++++++---------------
 xen/drivers/passthrough/vtd/quirks.c |   21 +-
 xen/drivers/passthrough/x86/Makefile |    1 +
 xen/drivers/passthrough/x86/arena.c  |  157 +++
 xen/drivers/passthrough/x86/iommu.c  |  104 +-
 xen/include/hypercall-defs.c         |    6 +
 xen/include/public/pv-iommu.h        |  114 ++
 xen/include/public/xen.h             |    1 +
 xen/include/xen/iommu.h              |  120 +-
 xen/include/xen/pci.h                |    3 +
 30 files changed, 2855 insertions(+), 1309 deletions(-)
 create mode 100644 docs/designs/iommu-contexts.md
 create mode 100644 docs/designs/pv-iommu.md
 create mode 100644 xen/arch/x86/include/asm/arena.h
 create mode 100644 xen/common/pv-iommu.c
 create mode 100644 xen/drivers/passthrough/context.c
 create mode 100644 xen/drivers/passthrough/quarantine.c
 create mode 100644 xen/drivers/passthrough/x86/arena.c
 create mode 100644 xen/include/public/pv-iommu.h