From patchwork Mon Mar 2 18:44:25 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stanislav Spassov X-Patchwork-Id: 11416111 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 32C32924 for ; Mon, 2 Mar 2020 18:46:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 11ECE2166E for ; Mon, 2 Mar 2020 18:46:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="f6y485F3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727479AbgCBSq3 (ORCPT ); Mon, 2 Mar 2020 13:46:29 -0500 Received: from smtp-fw-6002.amazon.com ([52.95.49.90]:56252 "EHLO smtp-fw-6002.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727126AbgCBSq3 (ORCPT ); Mon, 2 Mar 2020 13:46:29 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1583174788; x=1614710788; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=zo+xgKja6kmPxHfkNHFXpC45vKnXxIgJgU/su5JdReI=; b=f6y485F3J3AonfQxysgWrgIhGTyTFE13yarn7e9QVJerGwcK/cXBOhgE SIMKFRV9nqid8Wh3GP7XEd484iYaPQkHul+ChwdyZOxa0LGT/DG4+Rnuv nI9/HQB0bLQpXdQlwDz6hUr2XKleSo4LEKIlm5DBYhNyjXlq/4LEcJX3T I=; IronPort-SDR: 7NsYMCMRNrT/UHe7DWpaREhel35xf/uLqGgyEbI40WuPU2ES+S0dS0606b9McECDA/HIeXIlum ovC5OrGm0ZDA== X-IronPort-AV: E=Sophos;i="5.70,507,1574121600"; d="scan'208";a="19142125" Received: from iad12-co-svc-p1-lb1-vlan3.amazon.com (HELO email-inbound-relay-2b-5bdc5131.us-west-2.amazon.com) ([10.43.8.6]) by smtp-border-fw-out-6002.iad6.amazon.com with ESMTP; 02 Mar 2020 18:46:26 +0000 Received: from EX13MTAUEA002.ant.amazon.com (pdx4-ws-svc-p6-lb7-vlan3.pdx.amazon.com [10.170.41.166]) by email-inbound-relay-2b-5bdc5131.us-west-2.amazon.com (Postfix) with ESMTPS id BB6F7A16C0; Mon, 2 Mar 2020 18:46:24 +0000 (UTC) Received: from EX13D12EUC004.ant.amazon.com (10.43.164.129) by EX13MTAUEA002.ant.amazon.com (10.43.61.77) with Microsoft SMTP Server (TLS) id 15.0.1236.3; Mon, 2 Mar 2020 18:46:10 +0000 Received: from EX13MTAUWB001.ant.amazon.com (10.43.161.207) by EX13D12EUC004.ant.amazon.com (10.43.164.129) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Mon, 2 Mar 2020 18:46:08 +0000 Received: from u961addbe640f56.ant.amazon.com (10.28.84.111) by mail-relay.amazon.com (10.43.161.249) with Microsoft SMTP Server id 15.0.1367.3 via Frontend Transport; Mon, 2 Mar 2020 18:46:05 +0000 From: Stanislav Spassov To: CC: Stanislav Spassov , Bjorn Helgaas , Thomas Gleixner , Andrew Morton , =?utf-8?q?Jan_H_=2E_Sch=C3=B6nhe?= =?utf-8?q?rr?= , Jonathan Corbet , Ashok Raj , Alex Williamson , "Sinan Kaya" , Rajat Jain Subject: [PATCH v2 13/17] PCI: Cache CRS Software Visibiliy in struct pci_dev Date: Mon, 2 Mar 2020 19:44:25 +0100 Message-ID: <20200302184429.12880-14-stanspas@amazon.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200302184429.12880-1-stanspas@amazon.com> References: <20200302184429.12880-1-stanspas@amazon.com> MIME-Version: 1.0 Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org From: Stanislav Spassov Arguably, since CRS SV is a capability of Root Ports and determines how Root Ports will handle incoming CRS Completions, it makes more sense to store this flag in the struct pci bus that represents the port's secondary bus, and to cache it in any buses further down the hierarchy. However, storing the flag in struct pci_dev allows individual devices to be marked as not supporting CRS properly even when CRS SV is enabled on their parent Root Port. This way, future code that relies on the new flag will not be misled that it is safe to probe a device by relying on CRS SV to not cause platform timeouts (See the note on CRS SV on p. 553 of PCI Express Base Specification r5.0 from May 22, 2019). Note: Endpoints integrated into the Root Complex (RCiEP) may also be capable of using CRS. In that case, the software visibility is controlled using a Root Complex Register Block (RCRB). This is currently not supported by the kernel. The code introduced here would simply not set the newly introduced flag for RCiEP as for those bus->self is NULL. Signed-off-by: Stanislav Spassov --- drivers/pci/probe.c | 8 +++++++- include/linux/pci.h | 3 +++ 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 512cb4312ddd..eeff8a07f330 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1080,9 +1080,11 @@ static void pci_enable_crs(struct pci_dev *pdev) /* Enable CRS Software Visibility if supported */ pcie_capability_read_word(pdev, PCI_EXP_RTCAP, &root_cap); - if (root_cap & PCI_EXP_RTCAP_CRSVIS) + if (root_cap & PCI_EXP_RTCAP_CRSVIS) { pcie_capability_set_word(pdev, PCI_EXP_RTCTL, PCI_EXP_RTCTL_CRSSVE); + pdev->crssv_enabled = true; + } } static unsigned int pci_scan_child_bus_extend(struct pci_bus *bus, @@ -2414,6 +2416,10 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus) list_add_tail(&dev->bus_list, &bus->devices); up_write(&pci_bus_sem); + /* Propagate CRS Software Visibility bit from the parent bridge */ + if (bus->self) + dev->crssv_enabled = bus->self->crssv_enabled; + ret = pcibios_add_device(dev); WARN_ON(ret < 0); diff --git a/include/linux/pci.h b/include/linux/pci.h index 16dbfff2092e..1763e98625b9 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -386,6 +386,9 @@ struct pci_dev { bit manually */ unsigned int ignore_reset_delay_on_sx_resume:1; /* Cached value from pci_host_bridge */ + unsigned int crssv_enabled:1; /* Configuration Request Retry + Status Software Visibility + enabled on (parent) bridge */ unsigned int delay[PCI_INIT_EVENT_COUNT]; /* minimum waiting time after various events in ms */