From patchwork Fri Mar 18 17:42:57 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Robin Murphy X-Patchwork-Id: 12785715 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 19A64C433EF for ; Fri, 18 Mar 2022 17:43:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239729AbiCRRoa (ORCPT ); Fri, 18 Mar 2022 13:44:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41908 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239714AbiCRRo2 (ORCPT ); Fri, 18 Mar 2022 13:44:28 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id BE72E9F3A3; Fri, 18 Mar 2022 10:43:08 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8B36D1515; Fri, 18 Mar 2022 10:43:08 -0700 (PDT) Received: from e121345-lin.cambridge.arm.com (e121345-lin.cambridge.arm.com [10.1.196.40]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 254333F7B4; Fri, 18 Mar 2022 10:43:07 -0700 (PDT) From: Robin Murphy To: joro@8bytes.org, baolu.lu@linux.intel.com, andreas.noever@gmail.com, michael.jamet@intel.com, mika.westerberg@linux.intel.com, YehezkelShB@gmail.com Cc: iommu@lists.linux-foundation.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, mario.limonciello@amd.com, hch@lst.de Subject: [PATCH v2 1/2] iommu: Add capability for pre-boot DMA protection Date: Fri, 18 Mar 2022 17:42:57 +0000 Message-Id: <797c70d255f946c4d631f2ffc67f277cfe0cb97c.1647624084.git.robin.murphy@arm.com> X-Mailer: git-send-email 2.28.0.dirty In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org VT-d's dmar_platform_optin() actually represents a combination of properties fairly well standardised by Microsoft as "Pre-boot DMA Protection" and "Kernel DMA Protection"[1]. As such, we can provide interested consumers with an abstracted capability rather than driver-specific interfaces that won't scale. We name it for the former aspect since that's what external callers are most likely to be interested in; the latter is for the IOMMU layer to handle itself. Also use this as an opportunity to draw a line in the sand and add a new interface so as not to introduce any more callers of iommu_capable() which I also want to get rid of. For now it's a quick'n'dirty wrapper function, but will evolve to subsume the internal interface in future. [1] https://docs.microsoft.com/en-us/windows-hardware/design/device-experiences/oem-kernel-dma-protection Suggested-by: Christoph Hellwig Signed-off-by: Robin Murphy Reviewed-by: Christoph Hellwig --- v2: New patch drivers/iommu/intel/iommu.c | 2 ++ include/linux/iommu.h | 7 +++++++ 2 files changed, 9 insertions(+) diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index 0c7975848972..20d8e1f60068 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -4817,6 +4817,8 @@ static bool intel_iommu_capable(enum iommu_cap cap) return domain_update_iommu_snooping(NULL); if (cap == IOMMU_CAP_INTR_REMAP) return irq_remapping_enabled == 1; + if (cap == IOMMU_CAP_PRE_BOOT_PROTECTION) + return dmar_platform_optin(); return false; } diff --git a/include/linux/iommu.h b/include/linux/iommu.h index 4a25f8241207..e16d54e15fee 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -107,6 +107,8 @@ enum iommu_cap { transactions */ IOMMU_CAP_INTR_REMAP, /* IOMMU supports interrupt isolation */ IOMMU_CAP_NOEXEC, /* IOMMU_NOEXEC flag */ + IOMMU_CAP_PRE_BOOT_PROTECTION, /* Firmware says it used the IOMMU for + DMA protection and we should too */ }; /* These are the possible reserved region types */ @@ -1042,6 +1044,11 @@ static inline size_t iommu_map_sgtable(struct iommu_domain *domain, return iommu_map_sg(domain, iova, sgt->sgl, sgt->orig_nents, prot); } +static inline bool dev_iommu_capable(struct device *dev, enum iommu_cap cap) +{ + return device_iommu_mapped(dev) && iommu_capable(dev->bus, cap); +} + #ifdef CONFIG_IOMMU_DEBUGFS extern struct dentry *iommu_debugfs_dir; void iommu_debugfs_setup(void);