On 2023/12/15 11:32, Nicolin Chen wrote:
On Fri, Dec 15, 2023 at 03:04:44AM +0000, Tian, Kevin wrote:
From: Nicolin Chen nicolinc@nvidia.com Sent: Friday, December 15, 2023 10:28 AM On Fri, Dec 15, 2023 at 01:50:07AM +0000, Tian, Kevin wrote:
From: Liu, Yi L yi.l.liu@intel.com Sent: Thursday, December 14, 2023 7:27 PM
On 2023/11/17 21:18, Yi Liu wrote:> This adds the data structure for flushing iotlb for the nested domain
+struct iommu_hwpt_vtd_s1_invalidate {
__aligned_u64 addr;__aligned_u64 npages;__u32 flags;__u32 __reserved;__u32 error;__u32 dev_id;+};
dev_id is used to report the failed device, userspace should be able to
map
it to a vRID, and inject it to VM as part of ITE/ICE error.
and for this error reporting case what we actually require is the reverse map i.e. pRID->vRID. Not sure whether we can leverage the same RID mapping uAPI as for ARM/AMD but ignore viommu_id and then store vRID under device_domain_info. a bit tricky on life cycle management and also incompatible with SIOV...
One thing that I am not very clear here: since both vRID and dev_id are given by the VMM, shouldn't it already know the mapping if the point is to translate (pRID->)dev_id->vRID?
it's true for current Qemu.
but there is plan to support Qemu accepting a fd passed by Libvirt. In that case Qemu even doesn't see the sysfs path hence is not aware of pRID. otherwise yes we could leave the translation to VMM instead.
I think I misread Yi's narrative: dev_id is a working approach for VMM to convert to a vRID, while he is asking for a better alternative :)
In concept, dev_id works, but in reality we have problem to get a dev_id for a given device in intel iommu driver, hence I'm asking for help here. :)