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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 3B152C64E8A for ; Sat, 28 Nov 2020 21:58:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0EC7C2225E for ; Sat, 28 Nov 2020 21:58:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391357AbgK1V6M (ORCPT ); Sat, 28 Nov 2020 16:58:12 -0500 Received: from mga11.intel.com ([192.55.52.93]:45311 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391431AbgK1V6I (ORCPT ); Sat, 28 Nov 2020 16:58:08 -0500 IronPort-SDR: QPxc2KfhL7zJsxy4ejqThiH+7qjG89vFDZFGu7g8HVnlEGC4VBo69v+iYMLVoIXEzSh/qlHV1C 3aq/Wg2VUf3w== X-IronPort-AV: E=McAfee;i="6000,8403,9819"; a="169004412" X-IronPort-AV: E=Sophos;i="5.78,378,1599548400"; d="scan'208";a="169004412" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Nov 2020 13:56:27 -0800 IronPort-SDR: keiUCRZk0TETNAPKJJJSCo/axBw1rmuISWUohGFmnDDMhsRYMrr4gG9xcfXYQDTHbDPnW1i1/x eoa/pPpHqc2g== X-IronPort-AV: E=Sophos;i="5.78,378,1599548400"; d="scan'208";a="334094934" Received: from chhaviga-mobl.amr.corp.intel.com (HELO skuppusw-mobl5.amr.corp.intel.com) ([10.209.150.149]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Nov 2020 13:56:26 -0800 Subject: Re: [PATCH 1/5] PCI/DPC: Ignore devices with no AER Capability To: Bjorn Helgaas Cc: ashok.raj@intel.com, knsathya@kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Bjorn Helgaas , Olof Johansson References: <20201128215318.GA924062@bjorn-Precision-5520> From: "Kuppuswamy, Sathyanarayanan" Message-ID: <5646ac56-3b4a-d060-18ab-28722c337d00@linux.intel.com> Date: Sat, 28 Nov 2020 13:56:23 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201128215318.GA924062@bjorn-Precision-5520> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On 11/28/20 1:53 PM, Bjorn Helgaas wrote: > On Sat, Nov 28, 2020 at 01:49:46PM -0800, Kuppuswamy, Sathyanarayanan wrote: >> On 11/28/20 12:24 PM, Bjorn Helgaas wrote: >>> On Wed, Nov 25, 2020 at 06:01:57PM -0800, Kuppuswamy, Sathyanarayanan wrote: >>>> On 11/25/20 5:18 PM, Bjorn Helgaas wrote: >>>>> From: Bjorn Helgaas >>>>> >>>>> Downstream Ports may support DPC regardless of whether they support AER >>>>> (see PCIe r5.0, sec 6.2.10.2). Previously, if the user booted with >>>>> "pcie_ports=dpc-native", it was possible for dpc_probe() to succeed even if >>>>> the device had no AER Capability, but dpc_get_aer_uncorrect_severity() >>>>> depends on the AER Capability. >>>>> >>>>> dpc_probe() previously failed if: >>>>> >>>>> !pcie_aer_is_native(pdev) && !pcie_ports_dpc_native >>>>> !(pcie_aer_is_native() || pcie_ports_dpc_native) # by De Morgan's law >>>>> >>>>> so it succeeded if: >>>>> >>>>> pcie_aer_is_native() || pcie_ports_dpc_native >>>>> >>>>> Fail dpc_probe() if the device has no AER Capability. >>>>> >>>>> Signed-off-by: Bjorn Helgaas >>>>> Cc: Olof Johansson >>>>> --- >>>>> drivers/pci/pcie/dpc.c | 3 +++ >>>>> 1 file changed, 3 insertions(+) >>>>> >>>>> diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c >>>>> index e05aba86a317..ed0dbc43d018 100644 >>>>> --- a/drivers/pci/pcie/dpc.c >>>>> +++ b/drivers/pci/pcie/dpc.c >>>>> @@ -287,6 +287,9 @@ static int dpc_probe(struct pcie_device *dev) >>>>> int status; >>>>> u16 ctl, cap; >>>>> + if (!pdev->aer_cap) >>>>> + return -ENOTSUPP; >>>> Don't we check aer_cap support in drivers/pci/pcie/portdrv_core.c ? >>>> >>>> We don't enable DPC service, if AER service is not enabled. And AER >>>> service is only enabled if AER capability is supported. >>>> >>>> So dpc_probe() should not happen if AER capability is not supported? >>> >>> I don't think that's always true. If I'm reading this right, we have >>> this: >>> >>> get_port_device_capability(...) >>> { >>> #ifdef CONFIG_PCIEAER >>> if (dev->aer_cap && ...) >>> services |= PCIE_PORT_SERVICE_AER; >>> #endif >>> >>> if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DPC) && >>> pci_aer_available() && >>> (pcie_ports_dpc_native || (services & PCIE_PORT_SERVICE_AER))) >>> services |= PCIE_PORT_SERVICE_DPC; >>> } >>> >>> and in the case where: >>> >>> - CONFIG_PCIEAER=y >>> - booted with "pcie_ports=dpc-native" (pcie_ports_dpc_native is true) >>> - "dev" has no AER capability >>> - "dev" has DPC capability >>> >>> I think we do enable PCIE_PORT_SERVICE_DPC. >> Got it. But further looking into it, I am wondering whether >> we should keep this dependency? Currently we just use it to >> dump the error information. Do we need to create dependency >> between DPC and AER (which is functionality not dependent) just >> to see more details about the error? > > That's a good question, but I don't really want to get into the actual > operation of the AER and DPC drivers in this series, so maybe > something we should explore later. In that case, can you move this check to drivers/pci/pcie/portdrv_core.c? I don't see the point of distributed checks in both get_port_device_capability() and dpc_probe(). > -- Sathyanarayanan Kuppuswamy Linux Kernel Developer