Messages in this thread | ![/](/images/icornerl.gif) | | Date | Fri, 15 Dec 2023 12:01:19 +0800 | Subject | Re: [PATCH v7 1/3] iommufd: Add data structure for Intel VT-d stage-1 cache invalidation | From | Yi Liu <> |
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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. :)
-- Regards, Yi Liu
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