On 8/27/2025 7:04 AM, Daniel P. Berrangé 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@nvidia.com> --- 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>
We would expect separate FDs for each VFIO cdev (/dev/vfio/devices/vfioX) and a shared FD among the devices for /dev/iommu (the <iommufdId> value here). Agreed that we can turn this into a simple yes/no flag and put it under <driver>. I will note this for the next revision. Thanks, Nathan Chen