Jon Kohler 76e2dae01a qemu: fix switchover-ack regression for old qemu
When enabling switchover-ack on qemu from libvirt, the .party value
was set to both source and target; however, qemuMigrationParamsCheck()
only takes that into account to validate that the remote side of the
migration supports the flag if it is marked optional or auto/always on.

In the case of switchover-ack, when enabled on only the dst and not
the src, the migration will fail if the src qemu does not support
switchover-ack, as the dst qemu will issue a switchover-ack msg:
qemu/migration/savevm.c ->
  loadvm_process_command ->
    migrate_send_rp_switchover_ack(mis) ->
      migrate_send_rp_message(mis, MIG_RP_MSG_SWITCHOVER_ACK, 0, NULL)

Since the src qemu doesn't understand messages with header_type ==
MIG_RP_MSG_SWITCHOVER_ACK, qemu will kill the migration with error:
  qemu-kvm: RP: Received invalid message 0x0007 length 0x0000
  qemu-kvm: Unable to write to socket: Bad file descriptor

Looking at the original commit [1] for optional migration capabilities,
it seems that the spirit of optional handling was to enhance a given
existing capability where possible. Given that switchover-ack
exclusively depends on return-path, adding it as optional to that cap
feels right.

[1] 61e34b08568 ("qemu: Add support for optional migration capabilities")

Fixes: 1cc7737f69e ("qemu: add support for qemu switchover-ack")

Signed-off-by: Jon Kohler <jon@nutanix.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Avihai Horon <avihaih@nvidia.com>
Cc: Jiri Denemark <jdenemar@redhat.com>
Cc: Markus Armbruster <armbru@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: YangHang Liu <yanghliu@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
2024-06-28 08:50:12 +02:00
..
2024-02-26 11:03:51 +01:00
2024-06-25 14:46:03 +02:00
2024-06-19 12:15:26 +02:00
2024-06-21 09:56:57 +02:00
2024-06-19 14:28:38 +02:00

       libvirt library code README
       ===========================

The directory provides the bulk of the libvirt codebase. Everything
except for the libvirtd daemon and client tools. The build uses a
large number of libtool convenience libraries - one for each child
directory, and then links them together for the final libvirt.so,
although some bits get linked directly to libvirtd daemon instead.

The files directly in this directory are supporting the public API
entry points & data structures.

There are two core shared modules to be aware of:

 * util/  - a collection of shared APIs that can be used by any
            code. This directory is always in the include path
            for all things built

 * conf/  - APIs for parsing / manipulating all the official XML
            files used by the public API. This directory is only
            in the include path for driver implementation modules

 * vmx/   - VMware VMX config handling (used by esx/ and vmware/)


Then there are the hypervisor implementations:

 * bhyve         - bhyve - The BSD Hypervisor
 * esx/          - VMware ESX and GSX support using vSphere API over SOAP
 * hyperv/       - Microsoft Hyper-V support using WinRM
 * lxc/          - Linux Native Containers
 * openvz/       - OpenVZ containers using cli tools
 * qemu/         - QEMU / KVM using qemu CLI/monitor
 * remote/       - Generic libvirt native RPC client
 * test/         - A "mock" driver for testing
 * vbox/         - Virtual Box using native API
 * vmware/       - VMware Workstation and Player using the vmrun tool
 * xen/          - Xen using hypercalls, XenD SEXPR & XenStore


Finally some secondary drivers that are shared for several HVs.
Currently these are used by LXC, OpenVZ, QEMU and Xen drivers.
The ESX, Hyper-V, Remote, Test & VirtualBox drivers all
implement the secondary drivers directly

 * cpu/          - CPU feature management
 * interface/    - Host network interface management
 * network/      - Virtual NAT networking
 * nwfilter/     - Network traffic filtering rules
 * node_device/  - Host device enumeration
 * secret/       - Secret management
 * security/     - Mandatory access control drivers
 * storage/      - Storage management drivers


Since both the hypervisor and secondary drivers can be built as
dlopen()able modules, it is *FORBIDDEN* to have build dependencies
between these directories. Drivers are only allowed to depend on
the public API, and the internal APIs in the util/ and conf/
directories