> From: iommu-boun...@lists.linux-foundation.org [mailto:iommu- > boun...@lists.linux-foundation.org] On Behalf Of > sathyanarayanan.kuppusw...@linux.intel.com > Sent: Tuesday, February 12, 2019 5:51 AM > To: bhelg...@google.com; j...@8bytes.org; dw...@infradead.org > Cc: Raj, Ashok <ashok....@intel.com>; linux-...@vger.kernel.org; linux- > ker...@vger.kernel.org; Busch, Keith <keith.bu...@intel.com>; > iommu@lists.linux-foundation.org; Pan, Jacob jun > <jacob.jun....@intel.com> > Subject: [PATCH v2 2/2] iommu/vt-d: Enable PASID only if device expects > PASID in PRG Response. > > From: Kuppuswamy Sathyanarayanan > <sathyanarayanan.kuppusw...@linux.intel.com> > > In Intel IOMMU, if the Page Request Queue (PRQ) is full, it will > automatically respond to the device with a success message as a keep > alive. And when sending the success message, IOMMU will include PASID in > the Response Message when the Page Request has a PASID in Request > Message and It does not check against the PRG Response PASID > requirement > of the device before sending the response. Also, If the device receives the > PRG response with PASID when its not expecting it then the device behavior > is undefined. So enable PASID support only if device expects PASID in PRG > response message. > > Cc: Ashok Raj <ashok....@intel.com> > Cc: Jacob Pan <jacob.jun....@linux.intel.com> > Cc: Keith Busch <keith.bu...@intel.com> > Suggested-by: Ashok Raj <ashok....@intel.com> > Signed-off-by: Kuppuswamy Sathyanarayanan > <sathyanarayanan.kuppusw...@linux.intel.com> > --- > drivers/iommu/intel-iommu.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > 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. > > if (info->pri_supported && !pci_reset_pri(pdev) > && !pci_enable_pri(pdev, 32)) > -- > 2.20.1 > > _______________________________________________ > iommu mailing list > iommu@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/iommu _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
