Messages in this thread | | | Date | Tue, 28 Mar 2023 13:20:19 +0800 | Subject | Re: [PATCH v2 4/8] iommu/vt-d: Reserve RID_PASID from global SVA PASID space | From | Baolu Lu <> |
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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.
> > 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@linux.intel.com> > --- > 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.
> + /* 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
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