On Thu, Aug 14, 2025 at 07:54:12PM -0700, Nathan Chen via Devel wrote: > Implement iommufdId attribute for hostdev devices that > can be used to specify associated iommufd object when > launching a qemu VM. > > Signed-off-by: Nathan Chen <nathanc@xxxxxxxxxx> > --- > docs/formatdomain.rst | 9 +++++++++ > src/conf/domain_conf.c | 20 ++++++++++++++++++++ > src/conf/domain_conf.h | 1 + > src/conf/schemas/domaincommon.rng | 9 +++++++++ > src/qemu/qemu_command.c | 14 ++++++++++++++ > 5 files changed, 53 insertions(+) > > diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst > index 2558df18ef..e2b9be16c9 100644 > --- a/docs/formatdomain.rst > +++ b/docs/formatdomain.rst > @@ -4581,6 +4581,7 @@ or: > </source> > <boot order='1'/> > <rom bar='on' file='/etc/fake/boot.bin'/> > + <iommufdId>iommufd0</iommufdId> IIUC, the only place that is used is in the QEMU command line as an 'id' value. I'm sure we've discussed this before, but could you remind me - are we expecting every <hostdev> to have a separate iommufd FD, or are we expecting the same FD for all, or both/either ? ie we turn this into a simple yes/no flag ? If not, then we can probably turn this into a simple index value to express the uniqueness / sharing characteristics, without exposing the QEMU ID string concept directly. Either way, we can probably stuff this under <driver> rather than creating a new element eg <driver .... iommufd=yes|no> or <driver .... iommufdIndex="NNNN"/> depending on the answer to the previous Q> > </hostdev> > </devices> > ... > @@ -4829,6 +4830,14 @@ or: > device; if PCI ROM loading is disabled through this attribute, attempts to > tweak the loading process further using the ``bar`` or ``file`` attributes > will be rejected. :since:`Since 4.3.0 (QEMU and KVM only)`. > +``iommufdId`` > + The ``iommufdId`` element is used to specify using the iommufd interface to > + propagate DMA mappings to the kernel, instead of legacy VFIO. When the > + element is present, an iommufd object with its ID specified by ``iommufdId`` > + will be created by the resulting qemu command. Libvirt will open the > + /dev/iommu and VFIO device cdev, passing the associated file descriptor > + numbers to the qemu command. > + > ``address`` > The ``address`` element for USB devices has a ``bus`` and ``device`` > attribute to specify the USB bus and device number the device appears at on With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
