Hi Baolu, On Sat, 1 Apr 2023 21:43:13 +0800, Baolu Lu <baolu.lu@xxxxxxxxxxxxxxx> wrote: > On 2023/4/1 7:11, 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 PASID number space. Non-zero value can be used in RID_PASID on > > Intel VT-d. > > > > For ARM, AMD and others that _always_ use 0 as RID_PASID, there is no > > impact in that SVA PASID allocation base is 1. > > > > With this change, devices do both DMA with PASID and SVA 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..cbb2670f88ca 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; > > > > + /* Reserved RID_PASID from the global namespace for legacy DMA > > */ > > + WARN_ON(iommu_alloc_global_pasid(PASID_RID2PASID, > > PASID_RID2PASID) != > > + PASID_RID2PASID); > > This looks odd. With the previous patch unchanged, > iommu_alloc_global_pasid() will always return IOMMU_PASID_INVALID if > CONFIG_IOMMU_SVA is not set. right, will move out of CONFIG_IOMMU_SVA. good point! Thanks, Jacob
