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[Qemu-arm] [RFC v3 0/8] KVM PCI/MSI passthrough with mach-virt

From: Eric Auger
Subject: [Qemu-arm] [RFC v3 0/8] KVM PCI/MSI passthrough with mach-virt
Date: Thu, 6 Oct 2016 09:50:36 +0000

On ARM, MSI transactions emitted by passthrough'ed devices are translated
by the IOMMU.  So the host must allocate IOVAs and map them to the host
MSI frame physical addresses. Those IOVAs must be allocated within safe
GPA slots, unused by the guest.

The QEMU VFIO device retrieves the size if the IOVA window needed by the
host using a new VFIO IOMMU type capability chain API. This window is
allocated on guest address space withing the platform bus memory container.
This latter acts as a pool of usable GPA and comes with its own GPA allocator.
The memory region is tagged as "reserved_iova". The vfio_listener_region_add
callback is in charge of passing the window characteristics to the kernel
through an extended VFIO_IOMMU_MAP_DMA ioctl.

Best Regards


The series depends on the not yet upstream kernel series:
[PATCH v13 00/15] KVM PCIe/MSI passthrough on ARM/ARM64



RFCv2 -> RFC v3:
- IOVA aperture size is not arbitrary anymore. It is retrieved from the host
  usig VFIO IOMMU type capability chain API
- GPEX related patches removed since the warning is not seen anymore

RFC v1 -> RFC v2:
- now uses platform bus MMIO for mapping reserved IOVA region; hence the
  new patch file:
  "hw: platform-bus: enable to map any memory region onto the platform-bus"

Eric Auger (8):
  linux-headers: Partial update for MSI IOVA handling
  hw: vfio: common: vfio_get_iommu_type1_info
  hw: vfio: common: Introduce vfio_register_msi_iova
  memory: Add reserved_iova region type
  memory: memory_region_find_by_name
  hw: platform-bus: Enable to map any memory region onto the
  hw: vfio: common: vfio_prepare_msi_mapping
  hw: vfio: common: Adapt vfio_listeners for reserved_iova region

 hw/core/platform-bus.c     |  27 ++++---
 hw/vfio/common.c           | 175 +++++++++++++++++++++++++++++++++++++++------
 include/exec/memory.h      |  40 +++++++++++
 include/hw/platform-bus.h  |   7 ++
 linux-headers/linux/vfio.h |  48 +++++++++++--
 memory.c                   |  27 +++++++
 6 files changed, 288 insertions(+), 36 deletions(-)


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