From patchwork Mon Aug 13 18:19:46 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Myron Stowe X-Patchwork-Id: 10564623 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D6CC115A6 for ; Mon, 13 Aug 2018 18:19:49 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D05E128E48 for ; Mon, 13 Aug 2018 18:19:49 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C45FF29617; Mon, 13 Aug 2018 18:19:49 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5FD4928E48 for ; Mon, 13 Aug 2018 18:19:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729988AbeHMVDI (ORCPT ); Mon, 13 Aug 2018 17:03:08 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:59530 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729858AbeHMVDI (ORCPT ); Mon, 13 Aug 2018 17:03:08 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 04F264023461; Mon, 13 Aug 2018 18:19:46 +0000 (UTC) Received: from tak.stowe (ovpn-120-77.rdu2.redhat.com [10.10.120.77]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6C3E02142F20; Mon, 13 Aug 2018 18:19:46 +0000 (UTC) Subject: [PATCH 2/2] PCI: Match Root Port's MPS to endpoint's MPSS as necessary From: Myron Stowe To: bhelgaas@google.com, linux-pci@vger.kernel.org Cc: keith.busch@intel.com, jdmason@kudzu.us, okaya@kernel.org Date: Mon, 13 Aug 2018 12:19:46 -0600 Message-ID: <20180813181946.105655.94535.stgit@tak.stowe> In-Reply-To: <20180813181931.105655.22182.stgit@tak.stowe> References: <20180813181931.105655.22182.stgit@tak.stowe> User-Agent: StGit/0.18 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Mon, 13 Aug 2018 18:19:47 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Mon, 13 Aug 2018 18:19:47 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'myron.stowe@redhat.com' RCPT:'' Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP In commit 27d868b5e6cf ("PCI: Set MPS to match upstream bridge"), we made sure every device's MPS setting matches its upstream bridge, making it more likely that a hot-added device will work in a system with an optimized MPS configuration. Recently I've started encountering systems where the endpoint device's MPSS capability is less than its Root Port's current MPS value, thus the endpoint is not capable of matching its upstream bridge's MPS setting (see: bugzilla via "Link:" below). This leaves the system vulnerable - the upstream Root Port could respond with larger sized TLPs than the device can handle, and the device will consider them to be 'Malformed'. One could use the "pci=pcie_bus_safe" kernel parameter to resolve the issue, but, it both forces a user to have to supply a kernel parameter to get the system to function reliable, and may end up limiting MPS settings of other, non-related, sub-topologies which could benefit from maintaining their larger values. This patch augments Keith's approach to include tuning down a Root Port's MPS setting when its hot-added endpoint device is not capable of matching it. Link: https://bugzilla.kernel.org/show_bug.cgi?id=200527 Cc: Keith Busch Cc: Sinan Kaya Cc: Dongdong Liu Acked-by: Jon Mason Signed-off-by: Myron Stowe --- drivers/pci/probe.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index b285786..a1a243e 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1725,7 +1725,7 @@ int pci_setup_device(struct pci_dev *dev) static void pci_configure_mps(struct pci_dev *dev) { struct pci_dev *bridge = pci_upstream_bridge(dev); - int mps, p_mps, rc; + int mps, mpss, p_mps, rc; if (!pci_is_pcie(dev) || !bridge || !pci_is_pcie(bridge)) return; @@ -1753,6 +1753,14 @@ static void pci_configure_mps(struct pci_dev *dev) if (pcie_bus_config != PCIE_BUS_DEFAULT) return; + mpss = 128 << dev->pcie_mpss; + if (mpss < p_mps && pci_pcie_type(bridge) == PCI_EXP_TYPE_ROOT_PORT) { + pcie_set_mps(bridge, mpss); + pci_info(dev, "Upstream bridge's Max Payload Size set to %d (was %d, max %d)\n", + mpss, p_mps, 128 << bridge->pcie_mpss); + p_mps = pcie_get_mps(bridge); + } + rc = pcie_set_mps(dev, p_mps); if (rc) { pci_warn(dev, "can't set Max Payload Size to %d; if necessary, use \"pci=pcie_bus_safe\" and report a bug\n", @@ -1761,7 +1769,7 @@ static void pci_configure_mps(struct pci_dev *dev) } pci_info(dev, "Max Payload Size set to %d (was %d, max %d)\n", - p_mps, mps, 128 << dev->pcie_mpss); + p_mps, mps, mpss); } static struct hpp_type0 pci_default_type0 = {