Re: [PATCH v3 00/13] VIRTIO-IOMMU/VFIO: Don't assume 64b IOVA space

[Eric Auger]

Hi Yanghang,

On 10/19/23 11:07, YangHang Liu wrote:
> The original issue I found : After starting a VM which has two ice PFs
> and a virtio-iommu device, qemu-kvm and VM guest dmesg throw lots of
> duplicate VFIO_MAP_DMA errors
>
> After testing with Eric's build, the  original issue is gone and the
> Tier1 regression test against ice PF and virtio iommu device gets PASS
> as well.
>
> Tested-by: Yanghang Liu <yanghliu@redhat.com>

Thank you for testing!

Eric
>
>
> On Wed, Oct 18, 2023 at 9:45 PM Michael S. Tsirkin <mst@redhat.com> wrote:
>> On Wed, Oct 11, 2023 at 07:52:16PM +0200, Eric Auger wrote:
>>> This applies on top of vfio-next:
>>> https://github.com/legoater/qemu/, vfio-next branch
>> virtio things make sense
>>
>> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
>>
>> let me know how you want to merge all this.
>>
>>
>>
>>> On x86, when assigning VFIO-PCI devices protected with virtio-iommu
>>> we encounter the case where the guest tries to map IOVAs beyond 48b
>>> whereas the physical VTD IOMMU only supports 48b. This ends up with
>>> VFIO_MAP_DMA failures at qemu level because at kernel level,
>>> vfio_iommu_iova_dma_valid() check returns false on vfio_map_do_map().
>>>
>>> This is due to the fact the virtio-iommu currently unconditionally
>>> exposes an IOVA range of 64b through its config input range fields.
>>>
>>> This series removes this assumption by retrieving the usable IOVA
>>> regions through the VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE UAPI when
>>> a VFIO device is attached. This info is communicated to the
>>> virtio-iommu memory region, transformed into the inversed info, ie.
>>> the host reserved IOVA regions. Then those latter are combined with the
>>> reserved IOVA regions set though the virtio-iommu reserved-regions
>>> property. That way, the guest virtio-iommu driver, unchanged, is
>>> able to probe the whole set of reserved regions and prevent any IOVA
>>> belonging to those ranges from beeing used, achieving the original goal.
>>>
>>> Best Regards
>>>
>>> Eric
>>>
>>> This series can be found at:
>>> https://github.com/eauger/qemu/tree/vfio-next-iommu_geometry-v3
>>>
>>> History:
>>> v2 -> v3:
>>> - rebase on top of vfio-next (including iommufd prereq)
>>> - take into account IOVA range info capability may not be offered by
>>>   old kernel and use nr_iovas = -1 to encode that [Alex]
>>> - use GList * everywhere instead of arrays (in the range_inverse_array)
>>>   with the benefice it sorts ranges retrieved from the kernel which are
>>>   not garanteed to be sorted. Rework the tests accordingly [Alex]
>>> - Make sure resv_regions GList is build before the probe() [Jean]
>>>   per device list is first populated with prop resv regions on
>>>   IOMMUDevice creation and then rebuilt on set_iova()
>>> - Add a warning if set_iova builds a valid list after probe was
>>>   called [Jean]
>>> - Build host windows on top of IOVA valid ranges if this info can
>>>   be retrieved from the kernel. As many windows are created as
>>>   valid ranges
>>> v1 -> v2:
>>> - Remove "[PATCH 12/13] virtio-iommu: Resize memory region according
>>>   to the max iova info" which causes way too much trouble: trigger
>>>   a coredump in vhost, causes duplication of IOMMU notifiers causing
>>>   EEXIST vfio_dma_map errors, ... This looks like a bad usage of the
>>>   memory API so I prefer removing this from this series. So I was
>>>   also obliged to remove the vfio_find_hostwin() check in the case
>>>   of an IOMMU.
>>> - Let range_inverse_array() take low/high args instead of hardcoding
>>>   0, UINT64_MAX which both complexifies the algo and the tests.
>>> - Move range function description in header.
>>> - Check that if set_iova_ranges is called several times, new resv
>>>   regions are included in previous ones
>>>
>>> Eric Auger (13):
>>>   memory: Let ReservedRegion use Range
>>>   memory: Introduce memory_region_iommu_set_iova_ranges
>>>   vfio: Collect container iova range info
>>>   virtio-iommu: Rename reserved_regions into prop_resv_regions
>>>   range: Make range_compare() public
>>>   util/reserved-region: Add new ReservedRegion helpers
>>>   virtio-iommu: Introduce per IOMMUDevice reserved regions
>>>   range: Introduce range_inverse_array()
>>>   virtio-iommu: Record whether a probe request has been issued
>>>   virtio-iommu: Implement set_iova_ranges() callback
>>>   virtio-iommu: Consolidate host reserved regions and property set ones
>>>   test: Add some tests for range and resv-mem helpers
>>>   vfio: Remove 64-bit IOVA address space assumption
>>>
>>>  include/exec/memory.h            |  34 +++-
>>>  include/hw/vfio/vfio-common.h    |   2 +
>>>  include/hw/virtio/virtio-iommu.h |   7 +-
>>>  include/qemu/range.h             |  14 ++
>>>  include/qemu/reserved-region.h   |  32 ++++
>>>  hw/core/qdev-properties-system.c |   9 +-
>>>  hw/vfio/common.c                 |  23 ++-
>>>  hw/vfio/container.c              |  67 ++++++-
>>>  hw/virtio/virtio-iommu-pci.c     |   8 +-
>>>  hw/virtio/virtio-iommu.c         | 155 +++++++++++++--
>>>  system/memory.c                  |  13 ++
>>>  tests/unit/test-resv-mem.c       | 318 +++++++++++++++++++++++++++++++
>>>  util/range.c                     |  61 +++++-
>>>  util/reserved-region.c           |  91 +++++++++
>>>  hw/virtio/trace-events           |   1 +
>>>  tests/unit/meson.build           |   1 +
>>>  util/meson.build                 |   1 +
>>>  17 files changed, 791 insertions(+), 46 deletions(-)
>>>  create mode 100644 include/qemu/reserved-region.h
>>>  create mode 100644 tests/unit/test-resv-mem.c
>>>  create mode 100644 util/reserved-region.c
>>>
>>> --
>>> 2.41.0
>>