> From: Lu Baolu <baolu...@linux.intel.com> > Sent: Thursday, April 21, 2022 7:36 PM > > This field make the requests snoop processor caches irrespective of > other attributes in the request or other fields in paging structure > entries used to translate the request.
I think you want to first point out the fact that SVA wants snoop cache instead of just talking about the effect of PGSNP. But thinking more I wonder why PGSNP is ever required. This is similar to DMA API case. x86 is already cache coherent for normal DMA (if not setting PCI no-snoop) and if the driver knows no-snoop is incompatible to SVA API then it should avoid triggering no-snoop traffic for SVA usage. In this case it is pointless for IOMMU driver to enable force-snooping. Even in the future certain platform allows no-snoop usage w/ SVA (I'm not sure how it works) this again should be reflected by additional SVA APIs for driver to explicitly manage. force-snoop should be enabled only in device assignment case IMHO, orthogonal to whether vSVA is actually used. Did I misunderstand the motivation here? > > Signed-off-by: Lu Baolu <baolu...@linux.intel.com> > --- > drivers/iommu/intel/svm.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c > index 23a38763c1d1..c720d1be992d 100644 > --- a/drivers/iommu/intel/svm.c > +++ b/drivers/iommu/intel/svm.c > @@ -391,9 +391,12 @@ static struct iommu_sva > *intel_svm_bind_mm(struct intel_iommu *iommu, > } > > /* Setup the pasid table: */ > - sflags = (flags & SVM_FLAG_SUPERVISOR_MODE) ? > - PASID_FLAG_SUPERVISOR_MODE : 0; > - sflags |= cpu_feature_enabled(X86_FEATURE_LA57) ? > PASID_FLAG_FL5LP : 0; > + sflags = PASID_FLAG_PAGE_SNOOP; > + if (flags & SVM_FLAG_SUPERVISOR_MODE) > + sflags |= PASID_FLAG_SUPERVISOR_MODE; > + if (cpu_feature_enabled(X86_FEATURE_LA57)) > + sflags |= PASID_FLAG_FL5LP; > + > spin_lock_irqsave(&iommu->lock, iflags); > ret = intel_pasid_setup_first_level(iommu, dev, mm->pgd, mm- > >pasid, > FLPT_DEFAULT_DID, sflags); > -- > 2.25.1 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
