> From: Baolu Lu <baolu.lu@xxxxxxxxxxxxxxx> > Sent: Thursday, August 18, 2022 7:13 PM > >> rtaddr_reg = dmar_readq(iommu->reg + DMAR_RTADDR_REG); > >> - ext = !!(rtaddr_reg & DMA_RTADDR_RTT); > >> - new_ext = !!ecap_ecs(iommu->ecap); > >> + ext = !!(rtaddr_reg & DMA_RTADDR_SMT); > >> + new_ext = !!ecap_smts(iommu->ecap); > > > > should be !!sm_supported() > > Not really. The IOMMU was setup by the previous kernel. Here we just > check whether the scalable mode was enabled there. You want to compare whether old kernel and new kernel enable the same mode. ecap_smts is only about the capability. only sm_supported() can tell the mode which is actually used by the new kernel. > > > > >> > >> /* > >> * The RTT bit can only be changed when translation is disabled, > >> @@ -2747,6 +2705,10 @@ static int copy_translation_tables(struct > >> intel_iommu *iommu) > >> if (new_ext != ext) > >> return -EINVAL; > >> > >> + iommu->copied_tables = bitmap_zalloc(BIT_ULL(16), GFP_KERNEL); > >> + if (!iommu->copied_tables) > >> + return -ENOMEM; > >> + > >> old_rt_phys = rtaddr_reg & VTD_PAGE_MASK; > >> if (!old_rt_phys) > >> return -EINVAL; > > > > Out of curiosity. What is the rationale that we copy root table and > > context tables but not pasid tables? > > We only copy the context table and reconstruct it when the default > domain is attached. Before that, there's no need to reconstruct the > pasid table, hence it's safe to use the previous pasid tables. > I still didn't get why context table must be reconstructed but not pasid table...
