Merge tag 'migration-20230206-pull-request' of into staging

Migration Pull request

In this try
- rebase to latest upstream
- same than previous patch
- fix compilation on non linux (userfaultfd.h) (me)
- query-migrationthreads (jiang)
- fix race on reading MultiFDPages_t.block (zhenzhong)
- fix flush of zero copy page send reuest  (zhenzhong)

Please apply.

Previous try:
It includes:
- David Hildenbrand fixes for virtio-men
- David Gilbert canary to detect problems
- Fix for rdma return values (Fiona)
- Peter Xu uffd_open fixes
- Peter Xu show right downtime for postcopy
- manish.mishra msg fix fixes
- my vfio changes.

Please apply.

# iQIzBAABCAAdFiEEGJn/jt6/WMzuA0uC9IfvGFhy1yMFAmPhobYACgkQ9IfvGFhy
# 1yMNaA/9EHDPqrI1HL/VkJG4nNOOsQR7RbburXEberZOzvLjnqpjUD3Ls9qV6rx+
# ieHa5T4imYJFk72Wa5vx4r1/dCjtJD2W6jg5+/0nTvYAHrs1U1VRqpuTr0HiXdbJ
# ZLLCnW5eDyO3eMaOX0MUkgHgL0FNkc/Lq5ViCTFsMu9O9xMuDLLdAC3cdvslKuOu
# X1gKByr9jT817Y9e36amYmRaJKC6Cr/PIekNVFu12HBW79pPusLX8KWEf4RBw4HR
# sPwTvMCR/BwZ0+2Lppan60G5rt/ZxDu40oU7y+RHlfWqevl4hDM84/nhjMvEgzc5
# a4Ahe2ERGLwwnC8z3l7v9+pEzSGzDoPcnRGvZcpUpk68wTDtxd5Bdq8CwmNUfL07
# VzWcYpH0yvmwjBba9jfn9fAVgnG5rVp558XcYLIII3wEToty3UDtm43wSdj2CGr6
# cu+IPAp+n/I5G9SRYBTU9ozJz45ttnEe0hxUtZ4I3MuhzHi1VEDAqTWM/X0LyS41
# TB3Y5B2KKpJYbPyZEH4nyTeetR2k7alTFzahCgKqVfOgL0nJx54petjS1K+B1P72
# g6lhP9WnQ33W+M8S7J/aGEaDJd1lFyFB2Rdjn2ZZnASH/fR9j0mFmXWvulXtjFNp
# Sfim3887+Iv4Uzw4VWEe3mM5Ypi/Ba2CmuTjy/pM08Ey8X1Qs5o=
# =ZQbR
# gpg: Signature made Tue 07 Feb 2023 00:56:22 GMT
# gpg:                using RSA key 1899FF8EDEBF58CCEE034B82F487EF185872D723
# gpg: Good signature from "Juan Quintela <>" [full]
# gpg:                 aka "Juan Quintela <>" [full]
# Primary key fingerprint: 1899 FF8E DEBF 58CC EE03  4B82 F487 EF18 5872 D723

* tag 'migration-20230206-pull-request' of (30 commits)
  migration: save/delete migration thread info
  migration: Introduce interface query-migrationthreads
  multifd: Fix flush of zero copy page send request
  multifd: Fix a race on reading MultiFDPages_t.block
  migration: check magic value for deciding the mapping of channels
  io: Add support for MSG_PEEK for socket channel
  migration/dirtyrate: Show sample pages only in page-sampling mode
  migration: Perform vmsd structure check during tests
  migration: Add canary to VMSTATE_END_OF_LIST
  migration/rdma: fix return value for qio_channel_rdma_{readv,writev}
  migration: Show downtime during postcopy phase
  virtio-mem: Proper support for preallocation with migration
  virtio-mem: Migrate immutable properties early
  virtio-mem: Fail if a memory backend with "prealloc=on" is specified
  migration/ram: Factor out check for advised postcopy
  migration/vmstate: Introduce VMSTATE_WITH_TMP_TEST() and VMSTATE_BITMAP_TEST()
  migration/savevm: Allow immutable device state to be migrated early (i.e., before RAM)
  migration/savevm: Prepare vmdesc json writer in qemu_savevm_state_setup()
  migration/savevm: Move more savevm handling into vmstate_save()
  migration/ram: Optimize ram_write_tracking_start() for RamDiscardManager

Signed-off-by: Peter Maydell <>