From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Subject: [RFC PATCH] vfio/type1: Do not support IOMMUs that allow bypass Date: Thu, 15 Oct 2015 14:52:33 -0600 Message-ID: <20151015205046.28129.50479.stgit@gimli.home> 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@linaro.org To: alex.williamson@redhat.com Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org 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, 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;