Hi Kevin, On Thu, 2 Mar 2023 09:43:03 +0000, "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote: > > From: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx> > > Sent: Thursday, March 2, 2023 9:00 AM > > > > Global PASID allocation is under IOMMU SVA code since it is the primary > > use case. However, some architecture such as VT-d, global PASIDs are > > necessary for its internal use of DMA API with PASID. > > No, global PASID is not a VT-d restriction. It's from ENQCMD/S hence a > device requirement. I meant VT-d based platforms, it is kind of intertwined in that ENQCMDS does not restrict RIDPASID!=DMA PASID, vt-d does. Without this restriction, there wouldn't be a need for this patch. Let me reword. > > > > This patch introduces SVA APIs to reserve and release global PASIDs. > > > > Link: https://lore.kernel.org/all/20230301235646.2692846-4- > > jacob.jun.pan@xxxxxxxxxxxxxxx/ > > Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx> > > --- > > drivers/iommu/iommu-sva.c | 25 +++++++++++++++++++++++++ > > include/linux/iommu.h | 14 ++++++++++++++ > > 2 files changed, 39 insertions(+) > > > > diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c > > index 8c92a145e15d..cfdeafde88a9 100644 > > --- a/drivers/iommu/iommu-sva.c > > +++ b/drivers/iommu/iommu-sva.c > > @@ -149,6 +149,31 @@ u32 iommu_sva_get_pasid(struct iommu_sva > > *handle) > > } > > EXPORT_SYMBOL_GPL(iommu_sva_get_pasid); > > > > +ioasid_t iommu_sva_reserve_pasid(ioasid_t min, ioasid_t max) > > +{ > > + int ret; > > + > > + if (min == IOMMU_PASID_INVALID || max == > > IOMMU_PASID_INVALID || > > + min == 0 || max < min) > > + return IOMMU_PASID_INVALID; > > + > > + ret = ida_alloc_range(&iommu_global_pasid_ida, min, max, > > GFP_KERNEL); > > + if (ret < 0) > > + return IOMMU_PASID_INVALID; > > + > > + return ret; > > +} > > +EXPORT_SYMBOL_GPL(iommu_sva_reserve_pasid); > > + > > I'm not sure it's the right way. It's not related to SVA. > > We should move iommu_global_pasid_ida to iomm.c and then have > another interface for allocation. > > Above is pretty generic so probably a general one like: > > ioasid_t iommu_allocate_global_pasid(struct device *dev) > > internally it can use [1, dev->iommu->max_pasids] as min/max instead > of passed in from the caller. sounds good to me, will do. Thanks, Jacob
