From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anup Patel Subject: [PATCH 4/5] vfio: Allow No-IOMMU mode for IOMMUs with bypass capability Date: Wed, 19 Jul 2017 15:03:57 +0530 Message-ID: <1500456838-18405-5-git-send-email-anup.patel@broadcom.com> References: <1500456838-18405-1-git-send-email-anup.patel@broadcom.com> Return-path: In-Reply-To: <1500456838-18405-1-git-send-email-anup.patel@broadcom.com> Sender: linux-kernel-owner@vger.kernel.org To: Will Deacon , Robin Murphy , Joerg Roedel , Baptiste Reynal , Alex Williamson Cc: Scott Branden , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, iommu@lists.linux-foundation.org, kvm@vger.kernel.org, bcm-kernel-feedback-list@broadcom.com, Anup Patel List-Id: iommu@lists.linux-foundation.org Not allowing No-IOMMU mode for devices already having iommu_ops on their bus is little conservative. We now have IOMMU (such as ARM SMMU) which can bypass transcations for which IOMMU domain is not configured hence No-IOMMU mode should not be allowed when iommu_ops are available and IOMMU_CAP_BYPASS is not available. Signed-off-by: Anup Patel --- drivers/vfio/vfio.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index 330d505..61f3807 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -124,11 +124,18 @@ struct iommu_group *vfio_iommu_group_get(struct device *dev) #ifdef CONFIG_VFIO_NOIOMMU /* * With noiommu enabled, an IOMMU group will be created for a device - * that doesn't already have one and doesn't have an iommu_ops on their - * bus. We set iommudata simply to be able to identify these groups + * that: + * 1. Doesn't already have IOMMU group + * 2. Doesn't have an iommu_ops on their bus + * 3. Doesn't have transaction bypass capability if iommu_ops + * is available on their bus + * + * We set iommudata simply to be able to identify these groups * as special use and for reclamation later. */ - if (group || !noiommu || iommu_present(dev->bus)) + if (group || !noiommu || + (iommu_present(dev->bus) && + !iommu_capable(dev->bus, IOMMU_CAP_BYPASS))) return group; group = iommu_group_alloc(); -- 2.7.4