On Wed, Jan 14, 2026 at 13:18:51 +0100, Peter Krempa via Devel wrote:
> On Wed, Jan 14, 2026 at 10:42:02 +0000, Tejus GK wrote:
> > This API allows callers to pass and store file descriptors inside libvirt
> > using a hash table, with a provided "name" serving as the key. The stored
> > file descriptors can be queried and reused later, enabling use cases such as
> > FD-based live migration.
> >
> > Signed-off-by: Tejus GK <[email protected]>
> > ---
> > include/libvirt/libvirt-domain.h | 9 +++++
> > src/driver-hypervisor.h | 7 ++++
> > src/libvirt-domain.c | 62 +++++++++++++++++++++++++++++
> > src/libvirt_public.syms | 5 +++
> > src/qemu/qemu_conf.h | 4 ++
> > src/qemu/qemu_driver.c | 41 +++++++++++++++++++
> > src/remote/remote_daemon_dispatch.c | 36 +++++++++++++++++
> > src/remote/remote_driver.c | 22 ++++++++++
> > src/remote/remote_protocol.x | 12 +++++-
> > 9 files changed, 197 insertions(+), 1 deletion(-)
>
> [...]
>
> > diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c
> > index 74c70a0a43..7e194f7193 100644
> > --- a/src/libvirt-domain.c
> > +++ b/src/libvirt-domain.c
> > @@ -14269,3 +14269,65 @@ virDomainDelThrottleGroup(virDomainPtr dom,
> > virDispatchError(dom->conn);
> > return -1;
> > }
> > +
> > +
> > +/**
> > + * virDomainFDStore:
> > + * @conn: a connection object
> > + * @name: name for the file descriptor group
> > + * @nfds: number of fds in @fds
> > + * @fds: file descriptors to store
> > + *
> > + * Store the FDs in @fds with @conn under @name. The FDs persist unitl
> > + * explicitly consumed (e.g. during a live migration) or until libvirt
> > + * shuts down/ restarts.
> > + *
> > + * Unlike virDomainFDAssociate, this does not require a domain to exist
> > + * at the time of storing the FDs.
> > + *
> > + * Returns 0 on success, -1 on error.
> > + *
> > + * Since: 12.0.0
> > + */
>
> This looks identical to as long as you are about to use the FD with a VM
> object:
Looking at the usage in the code it seems to be in a place which has
@domain available, so no new API should be required for this usage.
>
> /**
> * virDomainFDAssociate:
> * @domain: a domain object
> * @name: name for the file descriptor group
> * @nfds: number of fds in @fds
> * @fds: file descriptors to associate with domain
> * @flags: optional flags; bitwise-OR of supported virDomainFDAssociateFlags
> *
> * Associate the FDs in @fd with @domain under @name. The FDs are associated
> as
> * long as the connection used to associated exists and are disposed of
> * afterwards. FD may still be kept open by the hypervisor for as long as it's
> * needed.
> *
> * Security labelling (e.g. via the selinux) may be applied on the passed FDs
> * when required for usage by the VM. By default libvirt does not restore the
> * seclabels on the FDs afterwards to avoid keeping it open unnecessarily.
> *
> * Restoring of the security label can be requested by passing either
> * VIR_DOMAIN_FD_ASSOCIATE_SECLABEL_RESTORE for a best-effort attempt to
> restore
> * the security label after use.
> * Requesting the restore of security label will require that the file
> * descriptors are kept open for the whole time they are used by the
> hypervisor,
> * or other additional overhead.
> *
> * In certain cases usage of the fd group would imply read-only access.
> Passing
> * VIR_DOMAIN_FD_ASSOCIATE_SECLABEL_WRITABLE in @flags ensures that a writable
> * security label is picked in case when the file represented by the fds may
> * be used in write mode.
> *
> * Returns 0 on success, -1 on error.
> *
> * Since: 9.0.0
> */
> int
> virDomainFDAssociate(virDomainPtr domain,
> const char *name,
> unsigned int nfds,
> int *fds,
> unsigned int flags)
>
>
> > + int
> > + virDomainFDStore(virConnectPtr conn,
> > + const char *name,
> > + unsigned int nfds,
> > + int *fds)
> > + {
> > + int rc;
> > +
> > + VIR_DEBUG("conn=%p, name='%s', nfds=%u, fds=%p",
> > + conn, name, nfds, fds);
>
