On Wed, Feb 13, 2019 at 12:26:33AM -0800, Tian, Kevin wrote: > > > > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c > > index 1457f931218e..af2e4a011787 100644 > > --- a/drivers/iommu/intel-iommu.c > > +++ b/drivers/iommu/intel-iommu.c > > @@ -1399,7 +1399,8 @@ static void iommu_enable_dev_iotlb(struct > > device_domain_info *info) > > undefined. So always enable PASID support on devices which > > have it, even if we can't yet know if we're ever going to > > use it. */ > > - if (info->pasid_supported && !pci_enable_pasid(pdev, info- > > >pasid_supported & ~1)) > > + if (info->pasid_supported && pci_prg_resp_pasid_required(pdev) > > && > > + !pci_enable_pasid(pdev, info->pasid_supported & ~1)) > > info->pasid_enabled = 1; > > Above logic looks problematic. As Dave commented in another thread, > PRI and PASID are orthogonal capabilities. Especially with introduction > of VT-d scalable mode, PASID will be used alone even w/o PRI... > > Why not doing the check when PRI is actually enabled? At that point > you can fail the request if above condition is false. > That makes sense.
