| Message ID | 20230407180554.2784285-5-jacob.jun.pan@linux.intel.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Re-enable IDXD kernel workqueue under DMA API | expand |
On 4/8/23 2:05 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 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@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..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); How about moving above line up a bit? For example, at least before iommu_device_register(). This is the starting point where device drivers may want global PASIDs. Best regards, baolu
Hi Baolu, On Mon, 10 Apr 2023 09:59:45 +0800, Baolu Lu <baolu.lu@linux.intel.com> wrote: > On 4/8/23 2:05 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 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@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..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); > > How about moving above line up a bit? For example, at least before > iommu_device_register(). This is the starting point where device drivers > may want global PASIDs. > makes sense will do. Thanks, Jacob
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); + return 0; out_free_dmar:
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@linux.intel.com> --- drivers/iommu/intel/iommu.c | 4 ++++ 1 file changed, 4 insertions(+)