Hi Baolu, On Tue, 28 Mar 2023 13:20:19 +0800, Baolu Lu <baolu.lu@xxxxxxxxxxxxxxx> wrote: > On 3/28/23 7:21 AM, Jacob Pan wrote: > > On VT-d platforms, RID_PASID is used for DMA request without PASID. We > > should not treat RID_PASID special instead let it be allocated from the > > global SVA PASID number space. > > It's same to AMD and ARM SMMUv3, right? They also need an explicit > reservation of PASID 0. > yes, all IOMMU drivers need to do that. I will give it a try but might need help to place the call. > > > > Consequently, for devices also do DMA with PASID, drivers will not worry > > about conflicts when it comes to allocating PASIDs for in-kernel DMA. > > > > Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx> > > --- > > drivers/iommu/intel/iommu.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c > > index 9f737ef55463..61c06f7ad8f7 100644 > > --- a/drivers/iommu/intel/iommu.c > > +++ b/drivers/iommu/intel/iommu.c > > @@ -3956,6 +3956,10 @@ int __init intel_iommu_init(void) > > > > intel_iommu_enabled = 1; > > > > +#ifdef CONFIG_INTEL_IOMMU_SVM > > Do we really need this #ifdef? IOMMU_SVA is selected by INTEL_IOMMU_SVM, > right? So if CONFIG_INTEL_IOMMU_SVM is not set, > iommu_sva_reserve_pasid() is just a dumb. > good catch! will remove > > + /* Reserved RID_PASID from the global namespace for legacy DMA > > */ > > + iommu_sva_reserve_pasid(PASID_RID2PASID, PASID_RID2PASID); > > +#endif > > return 0; > > > > out_free_dmar: > > Best regards, > baolu Thanks, Jacob
