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Merge tag 'pull-vfio-20250715' of https://github.com/legoater/qemu into staging

Browse Source 
vfio queue:

* Fixed vfio-user issues reported by Coverity
* Tweaked VFIO migration with multifd to support aarch64
* Introduced a property to override a device PCI class code

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# gpg: Signature made Tue 15 Jul 2025 11:22:08 EDT
# gpg:                using RSA key A0F66548F04895EBFE6B0B6051A343C7CFFBECA1
# gpg: Good signature from "Cédric Le Goater <clg@redhat.com>" [full]
# gpg:                 aka "Cédric Le Goater <clg@kaod.org>" [full]
# Primary key fingerprint: A0F6 6548 F048 95EB FE6B  0B60 51A3 43C7 CFFB ECA1

* tag 'pull-vfio-20250715' of https://github.com/legoater/qemu:
  vfio/migration: Max in-flight VFIO device state buffers size limit
  vfio/migration: Add x-migration-load-config-after-iter VFIO property
  vfio/pci: Introduce x-pci-class-code option
  hw/vfio-user: fix use of uninitialized variable
  hw/vfio-user: wait for proxy close correctly
  hw/vfio: fix region fd initialization
  hw/vfio-user: add Cédric Le Goater as a maintainer

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Stefan Hajnoczi
2025-07-16 07:07:44 -04:00
parent 504632dcc6 300dcf58b7
commit f79afdf7da
16 changed files with 212 additions and 21 deletions
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docs/devel/migration/vfio.rst
+19
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@@ -247,3 +247,22 @@ The multifd VFIO device state transfer is controlled by
"x-migration-multifd-transfer" VFIO device property. This property defaults to
AUTO, which means that VFIO device state transfer via multifd channels is
attempted in configurations that otherwise support it.
Since the target QEMU needs to load device state buffers in-order it needs to
queue incoming buffers until they can be loaded into the device.
This means that a malicious QEMU source could theoretically cause the target
QEMU to allocate unlimited amounts of memory for such buffers-in-flight.
The "x-migration-max-queued-buffers-size" property allows capping the total size
of these VFIO device state buffers queued at the destination.
Because a malicious QEMU source causing OOM on the target is not expected to be
a realistic threat in most of VFIO live migration use cases and the right value
depends on the particular setup by default this queued buffers size limit is
disabled by setting it to UINT64_MAX.
Some host platforms (like ARM64) require that VFIO device config is loaded only
after all iterables were loaded, during non-iterables loading phase.
Such interlocking is controlled by "x-migration-load-config-after-iter" VFIO
device property, which in its default setting (AUTO) does so only on platforms
that actually require it.