From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6B3DAC433E1 for ; Sat, 4 Jul 2020 11:20:04 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 47BE020890 for ; Sat, 4 Jul 2020 11:20:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 47BE020890 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id 2A77387526; Sat, 4 Jul 2020 11:20:04 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id a48ZMXUaP6Mb; Sat, 4 Jul 2020 11:20:02 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by fraxinus.osuosl.org (Postfix) with ESMTP id 80EDB87534; Sat, 4 Jul 2020 11:20:02 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 7AA32C08A2; Sat, 4 Jul 2020 11:20:02 +0000 (UTC) Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) by lists.linuxfoundation.org (Postfix) with ESMTP id 7E1B3C088C for ; Sat, 4 Jul 2020 11:19:59 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id 601A689165 for ; Sat, 4 Jul 2020 11:19:59 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id ekw+jfb8ikHN for ; Sat, 4 Jul 2020 11:19:56 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by hemlock.osuosl.org (Postfix) with ESMTPS id C47BF8915B for ; Sat, 4 Jul 2020 11:19:55 +0000 (UTC) IronPort-SDR: Uas2spG/aE+cXp1qciu3IbUZ3iYWVXTsVb0+rtiFe5ySAXfA/9PwISSgQO/X73mll9URgEf8b3 IEGSLIcnrEfw== X-IronPort-AV: E=McAfee;i="6000,8403,9671"; a="134701887" X-IronPort-AV: E=Sophos;i="5.75,311,1589266800"; d="scan'208";a="134701887" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Jul 2020 04:19:53 -0700 IronPort-SDR: 9ess/Q65IBDgo99jWabfvxAds5WhlV+NMNJ7L7LmwJ8KqDhfjcr3BsuG2M8Gdfw1sYRBWmu3Sq P0GV72cmwauQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,311,1589266800"; d="scan'208";a="282521460" Received: from jacob-builder.jf.intel.com ([10.7.199.155]) by orsmga006.jf.intel.com with ESMTP; 04 Jul 2020 04:19:53 -0700 From: Liu Yi L To: alex.williamson@redhat.com, eric.auger@redhat.com, baolu.lu@linux.intel.com, joro@8bytes.org Subject: [PATCH v4 14/15] vfio: Document dual stage control Date: Sat, 4 Jul 2020 04:26:28 -0700 Message-Id: <1593861989-35920-15-git-send-email-yi.l.liu@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1593861989-35920-1-git-send-email-yi.l.liu@intel.com> References: <1593861989-35920-1-git-send-email-yi.l.liu@intel.com> Cc: jean-philippe@linaro.org, kevin.tian@intel.com, ashok.raj@intel.com, kvm@vger.kernel.org, stefanha@gmail.com, jun.j.tian@intel.com, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, yi.y.sun@intel.com, hao.wu@intel.com X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" From: Eric Auger The VFIO API was enhanced to support nested stage control: a bunch of new iotcls and usage guideline. Let's document the process to follow to set up nested mode. Cc: Kevin Tian CC: Jacob Pan Cc: Alex Williamson Cc: Eric Auger Cc: Jean-Philippe Brucker Cc: Joerg Roedel Cc: Lu Baolu Reviewed-by: Stefan Hajnoczi Signed-off-by: Eric Auger Signed-off-by: Liu Yi L --- v3 -> v4: *) add review-by from Stefan Hajnoczi v2 -> v3: *) address comments from Stefan Hajnoczi v1 -> v2: *) new in v2, compared with Eric's original version, pasid table bind and fault reporting is removed as this series doesn't cover them. Original version from Eric. https://lkml.org/lkml/2020/3/20/700 --- Documentation/driver-api/vfio.rst | 67 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 67 insertions(+) diff --git a/Documentation/driver-api/vfio.rst b/Documentation/driver-api/vfio.rst index f1a4d3c..0672c45 100644 --- a/Documentation/driver-api/vfio.rst +++ b/Documentation/driver-api/vfio.rst @@ -239,6 +239,73 @@ group and can access them as follows:: /* Gratuitous device reset and go... */ ioctl(device, VFIO_DEVICE_RESET); +IOMMU Dual Stage Control +------------------------ + +Some IOMMUs support 2 stages/levels of translation. Stage corresponds to +the ARM terminology while level corresponds to Intel's VTD terminology. +In the following text we use either without distinction. + +This is useful when the guest is exposed with a virtual IOMMU and some +devices are assigned to the guest through VFIO. Then the guest OS can use +stage 1 (GIOVA -> GPA or GVA->GPA), while the hypervisor uses stage 2 for +VM isolation (GPA -> HPA). + +Under dual stage translation, the guest gets ownership of the stage 1 page +tables and also owns stage 1 configuration structures. The hypervisor owns +the root configuration structure (for security reason), including stage 2 +configuration. This works as long as configuration structures and page table +formats are compatible between the virtual IOMMU and the physical IOMMU. + +Assuming the HW supports it, this nested mode is selected by choosing the +VFIO_TYPE1_NESTING_IOMMU type through: + + ioctl(container, VFIO_SET_IOMMU, VFIO_TYPE1_NESTING_IOMMU); + +This forces the hypervisor to use the stage 2, leaving stage 1 available +for guest usage. The guest stage 1 format depends on IOMMU vendor, and +it is the same with the nesting configuration method. User space should +check the format and configuration method after setting nesting type by +using: + + ioctl(container->fd, VFIO_IOMMU_GET_INFO, &nesting_info); + +Details can be found in Documentation/userspace-api/iommu.rst. For Intel +VT-d, each stage 1 page table is bound to host by: + + nesting_op->flags = VFIO_IOMMU_NESTING_OP_BIND_PGTBL; + memcpy(&nesting_op->data, &bind_data, sizeof(bind_data)); + ioctl(container->fd, VFIO_IOMMU_NESTING_OP, nesting_op); + +As mentioned above, guest OS may use stage 1 for GIOVA->GPA or GVA->GPA. +GVA->GPA page tables are available when PASID (Process Address Space ID) +is exposed to guest. e.g. guest with PASID-capable devices assigned. For +such page table binding, the bind_data should include PASID info, which +is allocated by guest itself or by host. This depends on hardware vendor. +e.g. Intel VT-d requires to allocate PASID from host. This requirement is +defined by the Virtual Command Support in VT-d 3.0 spec, guest software +running on VT-d should allocate PASID from host kernel. To allocate PASID +from host, user space should check the IOMMU_NESTING_FEAT_SYSWIDE_PASID +bit of the nesting info reported from host kernel. VFIO reports the nesting +info by VFIO_IOMMU_GET_INFO. User space could allocate PASID from host by: + + req.flags = VFIO_IOMMU_ALLOC_PASID; + ioctl(container, VFIO_IOMMU_PASID_REQUEST, &req); + +With first stage/level page table bound to host, it allows to combine the +guest stage 1 translation along with the hypervisor stage 2 translation to +get final address. + +When the guest invalidates stage 1 related caches, invalidations must be +forwarded to the host through + + nesting_op->flags = VFIO_IOMMU_NESTING_OP_CACHE_INVLD; + memcpy(&nesting_op->data, &inv_data, sizeof(inv_data)); + ioctl(container->fd, VFIO_IOMMU_NESTING_OP, nesting_op); + +Those invalidations can happen at various granularity levels, page, context, +... + VFIO User API ------------------------------------------------------------------------------- -- 2.7.4 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu