[PATCH V5 00/38] Live update: vfio and iommufd

[Steve Sistare <steven.sistare@oracle.com>]

Support vfio and iommufd devices with the cpr-transfer live migration mode.
Devices that do not support live migration can still support cpr-transfer,
allowing live update to a new version of QEMU on the same host, with no loss
of guest connectivity.

No user-visible interfaces are added.

For legacy containers:

Pass vfio device descriptors to new QEMU.  In new QEMU, during vfio_realize,
skip the ioctls that configure the device, because it is already configured.

Use VFIO_DMA_UNMAP_FLAG_VADDR to abandon the old VA's for DMA mapped
regions, and use VFIO_DMA_MAP_FLAG_VADDR to register the new VA in new
QEMU and update the locked memory accounting.  The physical pages remain
pinned, because the descriptor of the device that locked them remains open,
so DMA to those pages continues without interruption.  Mediated devices are
not supported, however, because they require the VA to always be valid, and
there is a brief window where no VA is registered.

Save the MSI message area as part of vfio-pci vmstate, and pass the interrupt
and notifier eventfd's to new QEMU.  New QEMU loads the MSI data, then the
vfio-pci post_load handler finds the eventfds in CPR state, rebuilds vector
data structures, and attaches the interrupts to the new KVM instance.  This
logic also applies to iommufd containers.

For iommufd containers:

Use IOMMU_IOAS_MAP_FILE to register memory regions for DMA when they are
backed by a file (including a memfd), so DMA mappings do not depend on VA,
which can differ after live update.  This allows mediated devices to be
supported.

Pass the iommufd and vfio device descriptors from old to new QEMU.  In new
QEMU, during vfio_realize, skip the ioctls that configure the device, because
it is already configured.

In new QEMU, call ioctl(IOMMU_IOAS_CHANGE_PROCESS) to update mm ownership and
locked memory accounting.

Patches 3 to 8 are specific to legacy containers.
Patches 21 to 36 are specific to iommufd containers.
The remainder apply to both.

Changes from previous versions:
  * V1 of this series contains minor changes from the "Live update: vfio" and
    "Live update: iommufd" series, mainly bug fixes and refactored patches.

Changes in V2:
  * refactored various vfio code snippets into new cpr helpers
  * refactored vfio struct members into cpr-specific structures
  * refactored various small changes into their own patches
  * split complex patches.  Notably:
    - split "refactor for cpr" into 5 patches
    - split "reconstruct device" into 4 patches
  * refactored vfio_connect_container using helpers and made its
    error recovery more robust.
  * moved vfio pci msi/vector/intx cpr functions to cpr.c
  * renamed "reused" to cpr_reused and cpr.reused
  * squashed vfio_cpr_[un]register_container to their call sites
  * simplified iommu_type setting after cpr
  * added cpr_open_fd and cpr_is_incoming helpers
  * removed changes from vfio_legacy_dma_map, and instead temporarily
    override dma_map and dma_unmap ops.
  * deleted error_report and returned Error to callers where possible.
  * simplified the memory_get_xlat_addr interface
  * fixed flags passed to iommufd_backend_alloc_hwpt
  * defined MIG_PRI_UNINITIALIZED
  * added maintainers

Changes in V3:
  * removed cleanup patches that were already pulled
  * rebased to latest master

Changes in V4:
  * added SPDX-License-Identifier
  * patch "vfio/container: preserve descriptors"
    - rewrote search loop in vfio_container_connect
    - do not return pfd from vfio_cpr_container_match
    - add helper for VFIO_GROUP_GET_DEVICE_FD
  * deleted patch "export vfio_legacy_dma_map"
  * patch "vfio/container: restore DMA vaddr"
    - deleted redundant error_report from vfio_legacy_cpr_dma_map
    - save old dma_map function
  * patch "vfio-pci: skip reset during cpr"
    - use cpr_is_incoming instead of cpr_reused
  * renamed err -> local_err in all new code
  * patch "export MSI functions"
    -  renamed with vfio_pci prefix, and defined wrappers for low level
       routines instead of exporting them.
  * patch "close kvm after cpr"
    - fixed build error for !CONFIG_KVM
  * added the cpr_resave_fd helper
  * dropped patch "pass ramblock to vfio_container_dma_map", relying on
    "pass MemoryRegion" from the vfio-user series instead.
  * deleted "reused" variables, replaced with cpr_is_incoming()
  * renamed cpr_needed_for_reuse -> cpr_incoming_needed
  * rewrote patch "pci: skip reset during cpr"
  * rebased to latest master

  for iommufd:
    * deleted redundant error_report from iommufd_backend_map_file_dma
    * added interface doc for dma_map_file
    * check return value of cpr_open_fd
    * deleted "export iommufd_cdev_get_info_iova_range"
    * deleted "reconstruct device"
    * deleted "reconstruct hw_caps"
    * deleted "define hwpt constructors"
    * separated cpr registration for iommufd be and vfio container
    * correctly attach to multiple containers per iommufd using ioas_id
    * simplified "reconstruct hwpt" by matching against hwpt_id.
    * added patch "add vfio_device_free_name"

Changes in V5:
  * dropped: vfio/pci: vfio_pci_put_device on failure
  * added: "vfio: doc changes for cpr"
  * deleted unnecessary include of vfio-cpr.h
  * fixed compilation for !CONFIG_VFIO and !CONFIG_IOMMUFD
  * misc minor changes
  * Added RB's, rebased to master

Steve Sistare (38):
  migration: cpr helpers
  migration: lower handler priority
  vfio/container: register container for cpr
  vfio/container: preserve descriptors
  vfio/container: discard old DMA vaddr
  vfio/container: restore DMA vaddr
  vfio/container: mdev cpr blocker
  vfio/container: recover from unmap-all-vaddr failure
  pci: export msix_is_pending
  pci: skip reset during cpr
  vfio-pci: skip reset during cpr
  vfio/pci: vfio_pci_vector_init
  vfio/pci: vfio_notifier_init
  vfio/pci: pass vector to virq functions
  vfio/pci: vfio_notifier_init cpr parameters
  vfio/pci: vfio_notifier_cleanup
  vfio/pci: export MSI functions
  vfio-pci: preserve MSI
  vfio-pci: preserve INTx
  migration: close kvm after cpr
  migration: cpr_get_fd_param helper
  backends/iommufd: iommufd_backend_map_file_dma
  backends/iommufd: change process ioctl
  physmem: qemu_ram_get_fd_offset
  vfio/iommufd: use IOMMU_IOAS_MAP_FILE
  vfio/iommufd: invariant device name
  vfio/iommufd: add vfio_device_free_name
  vfio/iommufd: device name blocker
  vfio/iommufd: register container for cpr
  migration: vfio cpr state hook
  vfio/iommufd: cpr state
  vfio/iommufd: preserve descriptors
  vfio/iommufd: reconstruct device
  vfio/iommufd: reconstruct hwpt
  vfio/iommufd: change process
  iommufd: preserve DMA mappings
  vfio/container: delete old cpr register
  vfio: doc changes for cpr

 docs/devel/migration/CPR.rst          |   5 +-
 qapi/migration.json                   |   6 +-
 hw/vfio/pci.h                         |  10 ++
 include/exec/cpu-common.h             |   1 +
 include/hw/pci/msix.h                 |   1 +
 include/hw/pci/pci_device.h           |   3 +
 include/hw/vfio/vfio-container-base.h |  18 +++
 include/hw/vfio/vfio-container.h      |   2 +
 include/hw/vfio/vfio-cpr.h            |  66 +++++++-
 include/hw/vfio/vfio-device.h         |   5 +
 include/migration/cpr.h               |  21 +++
 include/migration/vmstate.h           |   6 +-
 include/system/iommufd.h              |   7 +
 include/system/kvm.h                  |   1 +
 accel/kvm/kvm-all.c                   |  32 ++++
 accel/stubs/kvm-stub.c                |   5 +
 backends/iommufd.c                    | 101 +++++++++++-
 hw/pci/msix.c                         |   2 +-
 hw/pci/pci.c                          |   5 +
 hw/vfio/ap.c                          |   2 +-
 hw/vfio/ccw.c                         |   2 +-
 hw/vfio/container-base.c              |   9 ++
 hw/vfio/container.c                   |  97 +++++++++---
 hw/vfio/cpr-iommufd.c                 | 220 ++++++++++++++++++++++++++
 hw/vfio/cpr-legacy.c                  | 287 ++++++++++++++++++++++++++++++++++
 hw/vfio/cpr.c                         | 159 +++++++++++++++++--
 hw/vfio/device.c                      |  40 +++--
 hw/vfio/helpers.c                     |  10 ++
 hw/vfio/iommufd-stubs.c               |  18 +++
 hw/vfio/iommufd.c                     |  81 ++++++++--
 hw/vfio/listener.c                    |  19 ++-
 hw/vfio/pci.c                         | 231 ++++++++++++++++++++-------
 hw/vfio/platform.c                    |   2 +-
 hw/vfio/vfio-stubs.c                  |  13 ++
 migration/cpr-transfer.c              |  18 +++
 migration/cpr.c                       |  95 +++++++++--
 migration/migration.c                 |   1 +
 migration/savevm.c                    |   4 +-
 system/physmem.c                      |   5 +
 backends/trace-events                 |   2 +
 hw/vfio/meson.build                   |   5 +
 41 files changed, 1482 insertions(+), 135 deletions(-)
 create mode 100644 hw/vfio/cpr-iommufd.c
 create mode 100644 hw/vfio/cpr-legacy.c
 create mode 100644 hw/vfio/iommufd-stubs.c
 create mode 100644 hw/vfio/vfio-stubs.c

base-commit: bc98ffdc7577e55ab8373c579c28fe24d600c40f
-- 
1.8.3.1