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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0BE9CC7EE2A for ; Thu, 1 Jun 2023 13:38:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233251AbjFANi5 (ORCPT ); Thu, 1 Jun 2023 09:38:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43896 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232329AbjFANiy (ORCPT ); Thu, 1 Jun 2023 09:38:54 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D4C60107; Thu, 1 Jun 2023 06:38:50 -0700 (PDT) Received: from lhrpeml500005.china.huawei.com (unknown [172.18.147.207]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4QX6cc1HPkz67FSP; Thu, 1 Jun 2023 21:37:04 +0800 (CST) Received: from localhost (10.202.227.76) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.23; Thu, 1 Jun 2023 14:38:48 +0100 Date: Thu, 1 Jun 2023 14:38:47 +0100 From: Jonathan Cameron To: Terry Bowman CC: , , , , , , , , , Subject: Re: [PATCH v4 17/23] cxl/pci: Add RCH downstream port AER register discovery Message-ID: <20230601143847.000058ff@Huawei.com> In-Reply-To: <20230523232214.55282-18-terry.bowman@amd.com> References: <20230523232214.55282-1-terry.bowman@amd.com> <20230523232214.55282-18-terry.bowman@amd.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.227.76] X-ClientProxiedBy: lhrpeml500003.china.huawei.com (7.191.162.67) To lhrpeml500005.china.huawei.com (7.191.163.240) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 23 May 2023 18:22:08 -0500 Terry Bowman wrote: > Restricted CXL host (RCH) downstream port AER information is not currently > logged while in the error state. One problem preventing the error logging > is the AER and RAS registers are not accessible. The CXL driver requires > changes to find RCH downstream port AER and RAS registers for purpose of > error logging. > > RCH downstream ports are not enumerated during a PCI bus scan and are > instead discovered using system firmware, ACPI in this case.[1] The > downstream port is implemented as a Root Complex Register Block (RCRB). > The RCRB is a 4k memory block containing PCIe registers based on the PCIe > root port.[2] The RCRB includes AER extended capability registers used for > reporting errors. Note, the RCH's AER Capability is located in the RCRB > memory space instead of PCI configuration space, thus its register access > is different. Existing kernel PCIe AER functions can not be used to manage > the downstream port AER capabilities and RAS registers because the port was > not enumerated during PCI scan and the registers are not PCI config > accessible. > > Discover RCH downstream port AER extended capability registers. Use MMIO > accesses to search for extended AER capability in RCRB register space. > > [1] CXL 3.0 Spec, 9.11.2 - System Firmware View of CXL 1.1 Hierarchy > [2] CXL 3.0 Spec, 8.2.1.1 - RCH Downstream Port RCRB > > Co-developed-by: Robert Richter > Signed-off-by: Robert Richter > Signed-off-by: Terry Bowman Seems reasonable. Reviewed-by: Jonathan Cameron