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 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 11BAFCEACEF for ; Mon, 17 Nov 2025 09:42:16 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vKvjR-0006zH-J5; Mon, 17 Nov 2025 04:41:10 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vKvig-0005o0-44 for qemu-devel@nongnu.org; Mon, 17 Nov 2025 04:40:24 -0500 Received: from mgamail.intel.com ([192.198.163.9]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vKvie-0006Kp-7i for qemu-devel@nongnu.org; Mon, 17 Nov 2025 04:40:21 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1763372420; x=1794908420; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=s8x4SQJsqM3hIZ73DiLwWQChJ2mlRt/MJGgdnOThySk=; b=PNHtgrgyWanr8skw3YaU40LSDOINyJLkChmTG095PclTw9y38cIU2Xtz JnYKrQ3Vyp34UlgQ3+EzpzjHXjdnzYU4EbJReWXBXQvpO2Bs+lC/qzA6J iYcRh2GOvWVcT/1U7ZkZ2f/9kJ8B36O7y84smaC/zIWR/KYpHN4lPKxm4 9eWKDzvfc2/CxGlVlJRWPGzQ9tc/vcdtUNq/pkJzC5FsK2urnXhEpcca6 op6JQyAHM9B2q/GiIFye71LKnwruhFFuohZ/moULjiVgNxsp8Wqh8yfc/ J0eS9ZKkspiqBn6luvRMrvtbgtg6iFkyDfUisvcFhRLXpN6Xd1d08p9BZ Q==; X-CSE-ConnectionGUID: ZcR/AkDmSa2sIY3iqm4lFQ== X-CSE-MsgGUID: J95K7EoiT4G435SEltmNVQ== X-IronPort-AV: E=McAfee;i="6800,10657,11615"; a="76046121" X-IronPort-AV: E=Sophos;i="6.19,311,1754982000"; d="scan'208";a="76046121" Received: from fmviesa007.fm.intel.com ([10.60.135.147]) by fmvoesa103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Nov 2025 01:40:03 -0800 X-CSE-ConnectionGUID: D2ghcJ9iQnaxSeUxm0hfuQ== X-CSE-MsgGUID: u3tAczwUTdC1t6TTk9eR/g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.19,311,1754982000"; d="scan'208";a="190071021" Received: from unknown (HELO gnr-sp-2s-612.sh.intel.com) ([10.112.230.229]) by fmviesa007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Nov 2025 01:39:59 -0800 From: Zhenzhong Duan To: qemu-devel@nongnu.org Cc: alex@shazbot.org, clg@redhat.com, eric.auger@redhat.com, mst@redhat.com, jasowang@redhat.com, peterx@redhat.com, ddutile@redhat.com, jgg@nvidia.com, nicolinc@nvidia.com, skolothumtho@nvidia.com, joao.m.martins@oracle.com, clement.mathieu--drif@eviden.com, kevin.tian@intel.com, yi.l.liu@intel.com, chao.p.peng@intel.com, Zhenzhong Duan Subject: [PATCH v8 23/23] docs/devel: Add IOMMUFD nesting documentation Date: Mon, 17 Nov 2025 04:37:26 -0500 Message-ID: <20251117093729.1121324-24-zhenzhong.duan@intel.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20251117093729.1121324-1-zhenzhong.duan@intel.com> References: <20251117093729.1121324-1-zhenzhong.duan@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=192.198.163.9; envelope-from=zhenzhong.duan@intel.com; helo=mgamail.intel.com X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Add documentation about using IOMMUFD backed VFIO device with intel_iommu with x-flts=on. Suggested-by: Yi Liu Signed-off-by: Zhenzhong Duan Reviewed-by: Eric Auger --- docs/devel/vfio-iommufd.rst | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/docs/devel/vfio-iommufd.rst b/docs/devel/vfio-iommufd.rst index 3d1c11f175..474549903e 100644 --- a/docs/devel/vfio-iommufd.rst +++ b/docs/devel/vfio-iommufd.rst @@ -164,3 +164,28 @@ RAM discarding for mdev. ``vfio-ap`` and ``vfio-ccw`` devices don't have same issue as their backend devices are always mdev and RAM discarding is force enabled. + +Usage with intel_iommu featuring x-flts=on +------------------------------------- + +Only IOMMUFD backed VFIO device is supported when intel_iommu is configured +with x-flts=on, for legacy container backed VFIO device, below error shows: + +.. code-block:: none + + qemu-system-x86_64: -device vfio-pci,host=0000:02:00.0: vfio 0000:02:00.0: Failed to set vIOMMU: Need IOMMUFD backend when x-flts=on + +VFIO device under PCI bridge is unsupported, use PCIE bridge if necessary, +otherwise below error shows: + +.. code-block:: none + + qemu-system-x86_64: -device vfio-pci,host=0000:02:00.0,bus=bridge1,iommufd=iommufd0: vfio 0000:02:00.0: Failed to set vIOMMU: Host device downstream to a PCI bridge is unsupported when x-flts=on + +If host IOMMU has ERRATA_772415_SPR17, kexec or reboot from "intel_iommu=on,sm_on" +to "intel_iommu=on,sm_off" in guest is also unsupported. Configure scalable mode +off as below if it's not needed by guest. + +.. code-block:: bash + + -device intel-iommu,x-scalable-mode=off -- 2.47.1