[v3,0/5] s390x/pci: Accomodate vfio DMA limiting

Message

Matthew Rosato Sept. 15, 2020, 7:14 p.m. UTC

Kernel commit 492855939bdb added a limit to the number of outstanding DMA
requests for a type1 vfio container.  However, lazy unmapping in s390 can 
in fact cause quite a large number of outstanding DMA requests to build up
prior to being purged, potentially the entire guest DMA space.  This
results in unexpected 'VFIO_MAP_DMA failed: No space left on device'
conditions seen in QEMU.

This patchset adds support to qemu to retrieve the number of allowable DMA
requests via the VFIO_IOMMU_GET_INFO ioctl.  The patches are separated into
vfio hits which add support for reading in VFIO_IOMMU_GET_INFO capability
chains and getting the per-container dma_avail value, and s390 hits to 
track DMA usage on a per-container basis.

Associated kernel patch:
https://marc.info/?l=kvm&m=160019703922812&w=2

Changes from v2:
- Patch 1 (new): Added a placeholder linux-headers sync
- Patch 2: Re-arranged so that this patch that adds a shared routine for
  finding info capabilities is first
- Patch 3: Adjusted vfio_get_info_dma_avail() logic to be able to return
  true when the capability exists but the caller did not provide a buffer
  on input.
- Patch 4 (new): Introduce hw/s390x/s390-pci-vfio.* to better-separate PCI
  emulation code from code that interfaces with vfio
- Patch 4: s/s390_sync_dma_avail/s390_pci_update_dma_avail/ - Since it's
  now moved into a different file it can't be static so I added '_pci'.
- Patch 4: Use g_autofree as suggested - drop the goto/out as a result
- Patch 4+5: Added asserts() in a few locations per suggestion
- Patch 5: lowercase inline function names
- Patch 5: fix dma_avail initialization in rpcit_service_call() and ensure
  we still allow unmaps to call s390_pci_update_iotlb when dma_avail == 0

Matthew Rosato (5):
  linux-headers: update against 5.9-rc5
  vfio: Create shared routine for scanning info capabilities
  vfio: Find DMA available capability
  s390x/pci: Add routine to get the vfio dma available count
  s390x/pci: Honor DMA limits set by vfio

 hw/s390x/meson.build                               |   1 +
 hw/s390x/s390-pci-bus.c                            |  56 ++++++++-
 hw/s390x/s390-pci-bus.h                            |   9 ++
 hw/s390x/s390-pci-inst.c                           |  34 ++++-
 hw/s390x/s390-pci-inst.h                           |   3 +
 hw/s390x/s390-pci-vfio.c                           |  54 ++++++++
 hw/s390x/s390-pci-vfio.h                           |  17 +++
 hw/vfio/common.c                                   |  52 ++++++--
 include/hw/vfio/vfio-common.h                      |   2 +
 include/standard-headers/drm/drm_fourcc.h          | 140 +++++++++++++++++++++
 include/standard-headers/linux/ethtool.h           |  87 +++++++++++++
 include/standard-headers/linux/input-event-codes.h |   3 +-
 include/standard-headers/linux/vhost_types.h       |  11 ++
 include/standard-headers/linux/virtio_9p.h         |   4 +-
 include/standard-headers/linux/virtio_blk.h        |  26 ++--
 include/standard-headers/linux/virtio_config.h     |   8 +-
 include/standard-headers/linux/virtio_console.h    |   8 +-
 include/standard-headers/linux/virtio_net.h        |   6 +-
 include/standard-headers/linux/virtio_scsi.h       |  20 +--
 linux-headers/asm-generic/unistd.h                 |   6 +-
 linux-headers/asm-mips/unistd_n32.h                |   1 +
 linux-headers/asm-mips/unistd_n64.h                |   1 +
 linux-headers/asm-mips/unistd_o32.h                |   1 +
 linux-headers/asm-powerpc/kvm.h                    |   5 +
 linux-headers/asm-powerpc/unistd_32.h              |   1 +
 linux-headers/asm-powerpc/unistd_64.h              |   1 +
 linux-headers/asm-s390/kvm.h                       |   7 +-
 linux-headers/asm-s390/unistd_32.h                 |   1 +
 linux-headers/asm-s390/unistd_64.h                 |   1 +
 linux-headers/asm-x86/unistd_32.h                  |   1 +
 linux-headers/asm-x86/unistd_64.h                  |   1 +
 linux-headers/asm-x86/unistd_x32.h                 |   1 +
 linux-headers/linux/kvm.h                          |  10 +-
 linux-headers/linux/vfio.h                         |  18 ++-
 linux-headers/linux/vhost.h                        |   2 +
 35 files changed, 537 insertions(+), 62 deletions(-)
 create mode 100644 hw/s390x/s390-pci-vfio.c
 create mode 100644 hw/s390x/s390-pci-vfio.h