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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 0D0F5C433DF for ; Tue, 26 May 2020 23:07:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DFE032078C for ; Tue, 26 May 2020 23:07:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="DGE/PK5P" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391188AbgEZXHY (ORCPT ); Tue, 26 May 2020 19:07:24 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:32551 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2404484AbgEZXHY (ORCPT ); Tue, 26 May 2020 19:07:24 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1590534442; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=z/cPDNnfZwS0saAPWel+OCX7+QFUn/80dLbmwhQAzY0=; b=DGE/PK5PCGhpMETXVTAdZF73maXyN+vC/QqWWm3aMvssmQTIYbQux2AhSvxqrG/LABLK57 IHUVm0RPdiZ+2Qbr/Y7M/3Z0URGRntMn8vyfnO374Rif3dL7FMBDcURdtdz1RGoLqVQN2D rVYNZ5iS5i66d69hEaDSS95v88rBcEk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-265-_XID7VbqOomQugx1txeZ1A-1; Tue, 26 May 2020 19:07:18 -0400 X-MC-Unique: _XID7VbqOomQugx1txeZ1A-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id BFA28107ACCD; Tue, 26 May 2020 23:07:16 +0000 (UTC) Received: from x1.home (ovpn-112-195.phx2.redhat.com [10.3.112.195]) by smtp.corp.redhat.com (Postfix) with ESMTP id CA6A460C47; Tue, 26 May 2020 23:07:15 +0000 (UTC) Date: Tue, 26 May 2020 17:07:15 -0600 From: Alex Williamson To: Ashok Raj Cc: linux-pci@vger.kernel.org, Bjorn Helgaas , Joerg Roedel , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Lu Baolu , Darrel Goeddel , Mark Scott , Romil Sharma Subject: Re: [PATCH] iommu: Relax ACS requirement for Intel RCiEP devices. Message-ID: <20200526170715.18c0ee98@x1.home> In-Reply-To: <1590531455-19757-1-git-send-email-ashok.raj@intel.com> References: <1590531455-19757-1-git-send-email-ashok.raj@intel.com> Organization: Red Hat MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Tue, 26 May 2020 15:17:35 -0700 Ashok Raj wrote: > 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. >=20 >=20 > 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: > =E2=80=A2 The input address in the request is translated (through first-l= evel, > 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). > =E2=80=A2 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. > =E2=80=A2 Root-ports, and multi-function root-complex integrated endpoint= s, may > support additional peerto-peer control features by supporting PCI Expre= ss > Access Control Services (ACS) capability. Refer to ACS capability in > PCI Express specifications for details. >=20 > 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. >=20 > In one vendor system: Device 14.x were grouped in a single IOMMU group. >=20 > /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 >=20 > 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 >=20 > 14.0 and 14.2 are integrated devices, but legacy end points. > Whereas 14.3 was a PCIe compliant RCiEP. >=20 > 00:14.3 Network controller: Intel Corporation Device 9df0 (rev 30) > Capabilities: [40] Express (v2) Root Complex Integrated Endpoint, MSI 00 >=20 > This permits assigning this device to a guest VM. >=20 > 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 > --- > drivers/iommu/iommu.c | 13 ++++++++++++- > 1 file changed, 12 insertions(+), 1 deletion(-) >=20 > 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 =3D NULL; > struct iommu_group *group; > =20 > - 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 =3D=3D PCI_VENDOR_ID_INTEL && > + pci_pcie_type(pdev) =3D=3D PCI_EXP_TYPE_RC_END) || > + pci_acs_enabled(pdev, REQ_ACS_FLAGS)) > return NULL; > =20 > for_each_pci_dev(tmp) { Hi Ashok, As this is an Intel/VT-d standard, not a PCIe standard, why not implement this in pci_dev_specific_acs_enabled() with all the other quirks? Thanks, Alex