From patchwork Tue May 26 22:17:35 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Ashok Raj X-Patchwork-Id: 11571457 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 17029739 for ; Tue, 26 May 2020 22:17:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0527E208DB for ; Tue, 26 May 2020 22:17:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391271AbgEZWRk (ORCPT ); Tue, 26 May 2020 18:17:40 -0400 Received: from mga04.intel.com ([192.55.52.120]:7297 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389638AbgEZWRk (ORCPT ); Tue, 26 May 2020 18:17:40 -0400 IronPort-SDR: L8MtWR+/i5iHSz4CbrtfAQ72Pvgc8uU2hUFyN1E9rHbkUEag+yr8k1vWGAGSymn4ol6tWEi298 UpxgaDrnjf6A== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 May 2020 15:17:39 -0700 IronPort-SDR: LQRNBHg29mtUm+BYhW/F0JYJJY+Cx1gdDil/ex+yWAzjp61fCcXcLRRNl6lMtygMxkLl6ENDcN YPLwPdtukCtQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,439,1583222400"; d="scan'208";a="468512269" Received: from otc-nc-03.jf.intel.com ([10.54.39.25]) by fmsmga006.fm.intel.com with ESMTP; 26 May 2020 15:17:39 -0700 From: Ashok Raj To: linux-pci@vger.kernel.org, Bjorn Helgaas , Joerg Roedel Cc: Ashok Raj , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Lu Baolu , Alex Williamson , Darrel Goeddel , Mark Scott , Romil Sharma Subject: [PATCH] iommu: Relax ACS requirement for Intel RCiEP devices. Date: Tue, 26 May 2020 15:17:35 -0700 Message-Id: <1590531455-19757-1-git-send-email-ashok.raj@intel.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org All Intel platforms guarantee that all root complex implementations must send transactions up to IOMMU for address translations. Hence for RCiEP devices that are Vendor ID Intel, can claim exception for lack of ACS support. 3.16 Root-Complex Peer to Peer Considerations When DMA remapping is enabled, peer-to-peer requests through the Root-Complex must be handled as follows: • The input address in the request is translated (through first-level, second-level or nested translation) to a host physical address (HPA). The address decoding for peer addresses must be done only on the translated HPA. Hardware implementations are free to further limit peer-to-peer accesses to specific host physical address regions (or to completely disallow peer-forwarding of translated requests). • Since address translation changes the contents (address field) of the PCI Express Transaction Layer Packet (TLP), for PCI Express peer-to-peer requests with ECRC, the Root-Complex hardware must use the new ECRC (re-computed with the translated address) if it decides to forward the TLP as a peer request. • Root-ports, and multi-function root-complex integrated endpoints, may support additional peerto-peer control features by supporting PCI Express Access Control Services (ACS) capability. Refer to ACS capability in PCI Express specifications for details. Since Linux didn't give special treatment to allow this exception, certain RCiEP MFD devices are getting grouped in a single iommu group. This doesn't permit a single device to be assigned to a guest for instance. In one vendor system: Device 14.x were grouped in a single IOMMU group. /sys/kernel/iommu_groups/5/devices/0000:00:14.0 /sys/kernel/iommu_groups/5/devices/0000:00:14.2 /sys/kernel/iommu_groups/5/devices/0000:00:14.3 After the patch: /sys/kernel/iommu_groups/5/devices/0000:00:14.0 /sys/kernel/iommu_groups/5/devices/0000:00:14.2 /sys/kernel/iommu_groups/6/devices/0000:00:14.3 <<< new group 14.0 and 14.2 are integrated devices, but legacy end points. Whereas 14.3 was a PCIe compliant RCiEP. 00:14.3 Network controller: Intel Corporation Device 9df0 (rev 30) Capabilities: [40] Express (v2) Root Complex Integrated Endpoint, MSI 00 This permits assigning this device to a guest VM. Fixes: f096c061f552 ("iommu: Rework iommu_group_get_for_pci_dev()") Signed-off-by: Ashok Raj To: Joerg Roedel To: Bjorn Helgaas Cc: linux-kernel@vger.kernel.org Cc: iommu@lists.linux-foundation.org Cc: Lu Baolu Cc: Alex Williamson Cc: Darrel Goeddel Cc: Mark Scott , Cc: Romil Sharma Cc: Ashok Raj Reviewed-by: Kuppuswamy Sathyanarayanan --- drivers/iommu/iommu.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 2b471419e26c..31b595dfedde 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -1187,7 +1187,18 @@ static struct iommu_group *get_pci_function_alias_group(struct pci_dev *pdev, struct pci_dev *tmp = NULL; struct iommu_group *group; - if (!pdev->multifunction || pci_acs_enabled(pdev, REQ_ACS_FLAGS)) + /* + * Intel VT-d Specification Section 3.16, Root-Complex Peer to Peer + * Considerations manadate that all transactions in RCiEP's and + * even Integrated MFD's *must* be sent up to the IOMMU. P2P is + * only possible on translated addresses. This gives enough + * guarantee that such devices can be forgiven for lack of ACS + * support. + */ + if (!pdev->multifunction || + (pdev->vendor == PCI_VENDOR_ID_INTEL && + pci_pcie_type(pdev) == PCI_EXP_TYPE_RC_END) || + pci_acs_enabled(pdev, REQ_ACS_FLAGS)) return NULL; for_each_pci_dev(tmp) {