Hi all, it would be nice to get this into qemu 10.0. Without it, the
basic support for cpr-transfer already in 10.0 is much less interesting.
Soft feature freeze is 2024-03-12.
- Steve
On 2/14/2025 9:13 AM, Steve Sistare wrote:
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 5 to 14 are specific to legacy containers.
Patches 27 to 44 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
Steve Sistare (45):
MAINTAINERS: Add reviewer for CPR
migration: cpr helpers
migration: lower handler priority
vfio: vfio_find_ram_discard_listener
vfio/container: ram discard disable helper
vfio/container: reform vfio_connect_container cleanup
vfio/container: vfio_container_group_add
vfio/container: register container for cpr
vfio/container: preserve descriptors
vfio/container: export vfio_legacy_dma_map
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_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
vfio: return mr from vfio_get_xlat_addr
vfio: pass ramblock to vfio_container_dma_map
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: export iommufd_cdev_get_info_iova_range
vfio/iommufd: define hwpt constructors
vfio/iommufd: invariant device name
vfio/iommufd: fix cpr register
vfio/iommufd: register container for cpr
vfio/iommufd: preserve descriptors
vfio/iommufd: reconstruct device
vfio/iommufd: reconstruct hw_caps
vfio/iommufd: reconstruct hwpt
vfio/iommufd: change process
iommufd: preserve DMA mappings
vfio/container: delete old cpr register
MAINTAINERS | 12 ++
accel/kvm/kvm-all.c | 28 ++++
backends/iommufd.c | 83 ++++++++--
backends/trace-events | 2 +
hw/pci/msix.c | 2 +-
hw/pci/pci.c | 13 ++
hw/vfio/common.c | 91 ++++++++---
hw/vfio/container-base.c | 12 +-
hw/vfio/container.c | 216 +++++++++++++++++---------
hw/vfio/cpr-iommufd.c | 172 +++++++++++++++++++++
hw/vfio/cpr-legacy.c | 277 ++++++++++++++++++++++++++++++++++
hw/vfio/cpr.c | 176 +++++++++++++++++++--
hw/vfio/helpers.c | 20 +--
hw/vfio/iommufd.c | 139 +++++++++++++----
hw/vfio/meson.build | 4 +-
hw/vfio/pci.c | 194 ++++++++++++++++++------
hw/vfio/pci.h | 12 ++
hw/vfio/trace-events | 1 +
hw/virtio/vhost-vdpa.c | 8 +-
include/exec/cpu-common.h | 1 +
include/exec/memory.h | 6 +-
include/hw/pci/msix.h | 1 +
include/hw/vfio/vfio-common.h | 20 ++-
include/hw/vfio/vfio-container-base.h | 6 +-
include/hw/vfio/vfio-cpr.h | 69 +++++++++
include/migration/cpr.h | 10 ++
include/migration/vmstate.h | 6 +-
include/system/iommufd.h | 6 +
include/system/kvm.h | 1 +
migration/cpr-transfer.c | 18 +++
migration/cpr.c | 92 +++++++++++
migration/migration.c | 1 +
migration/savevm.c | 4 +-
system/memory.c | 19 +--
system/physmem.c | 5 +
35 files changed, 1490 insertions(+), 237 deletions(-)
create mode 100644 hw/vfio/cpr-iommufd.c
create mode 100644 hw/vfio/cpr-legacy.c
create mode 100644 include/hw/vfio/vfio-cpr.h
base-commit: de278e54aefed143526174335f8286f7437d20be
