From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Subject: Re: [RFC PATCH] vfio/type1: Do not support IOMMUs that allow bypass Date: Fri, 16 Oct 2015 09:51:22 -0600 Message-ID: <1445010682.4059.508.camel@redhat.com> References: <20151015205046.28129.50479.stgit@gimli.home> <5621039F.50609@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, "eric.auger" To: Will Deacon Return-path: Received: from mx1.redhat.com ([209.132.183.28]:41169 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932178AbbJPPvX (ORCPT ); Fri, 16 Oct 2015 11:51:23 -0400 In-Reply-To: <5621039F.50609@linaro.org> Sender: kvm-owner@vger.kernel.org List-ID: On Fri, 2015-10-16 at 16:03 +0200, Eric Auger wrote: > Hi Alex, > On 10/15/2015 10:52 PM, Alex Williamson wrote: > > We can only provide isolation if DMA is forced through the IOMMU > > aperture. Don't allow type1 to be used if this is not the case. > > > > Signed-off-by: Alex Williamson > > --- > > > > Eric, I see a number of IOMMU drivers enable this, do the ones you > > care about for ARM set geometry.force_aperture? Thanks, > I am currently using arm-smmu.c. I don't see force_aperture being set. Hi Will, Would it be possible to add iommu_domain_geometry support to arm-smmu.c? In addition to this test to verify that DMA cannot bypass the IOMMU, I'd eventually like to pass the aperture information out through the VFIO API. Thanks, Alex > > drivers/vfio/vfio_iommu_type1.c | 12 ++++++++++++ > > 1 file changed, 12 insertions(+) > > > > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > > index 57d8c37..6afa9d4 100644 > > --- a/drivers/vfio/vfio_iommu_type1.c > > +++ b/drivers/vfio/vfio_iommu_type1.c > > @@ -728,6 +728,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data, > > struct vfio_group *group, *g; > > struct vfio_domain *domain, *d; > > struct bus_type *bus = NULL; > > + struct iommu_domain_geometry geometry; > > int ret; > > > > mutex_lock(&iommu->lock); > > @@ -762,6 +763,17 @@ static int vfio_iommu_type1_attach_group(void *iommu_data, > > goto out_free; > > } > > > > + /* > > + * If a domain does not force DMA within the aperture, devices are not > > + * isolated and type1 is not an appropriate IOMMU model. > > + */ > > + ret = iommu_domain_get_attr(domain->domain, > > + DOMAIN_ATTR_GEOMETRY, &geometry); > > + if (ret || !geometry.force_aperture) { > > + ret = -EPERM; > > + goto out_domain; > > + } > > + > > if (iommu->nesting) { > > int attr = 1; > > > > >