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b=ysaUHQT8q1TEE0n1/9FeFWL7dizimBN2kHQcJSr/JS2lcyEzlaxcF4Yrxm9Mk+m6tPpCxnn4bEhbCShTf6ZaWq5ckdOK28yoNOsCOlR3lqViBLWvQ/0ZuFMoEmZUV26olfIpw7d9Fmhu1GK/Hr367G7vRZOWHdJBlRC8/cfG8gg= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from DS0PR12MB6390.namprd12.prod.outlook.com (2603:10b6:8:ce::7) by DS7PR12MB6334.namprd12.prod.outlook.com (2603:10b6:8:95::19) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8422.14; Fri, 7 Feb 2025 19:05:19 +0000 Received: from DS0PR12MB6390.namprd12.prod.outlook.com ([fe80::38ec:7496:1a35:599f]) by DS0PR12MB6390.namprd12.prod.outlook.com ([fe80::38ec:7496:1a35:599f%3]) with mapi id 15.20.8422.010; Fri, 7 Feb 2025 19:05:19 +0000 Message-ID: <7497d32c-14b0-4ee5-8e0c-70be470bee0d@amd.com> Date: Fri, 7 Feb 2025 13:05:14 -0600 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 05/16] PCI/AER: Add CXL PCIe Port correctable error support in AER service driver To: Gregory Price Cc: linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, nifan.cxl@gmail.com, dave@stgolabs.net, jonathan.cameron@huawei.com, dave.jiang@intel.com, alison.schofield@intel.com, vishal.l.verma@intel.com, dan.j.williams@intel.com, bhelgaas@google.com, mahesh@linux.ibm.com, ira.weiny@intel.com, oohall@gmail.com, Benjamin.Cheatham@amd.com, rrichter@amd.com, nathan.fontenot@amd.com, Smita.KoralahalliChannabasappa@amd.com, lukas@wunner.de, ming.li@zohomail.com, PradeepVineshReddy.Kodamati@amd.com, alucerop@amd.com References: <20250107143852.3692571-1-terry.bowman@amd.com> <20250107143852.3692571-6-terry.bowman@amd.com> Content-Language: en-US From: "Bowman, Terry" In-Reply-To: Content-Type: text/plain; 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It needs the same >> functionality for CXL PCIe Ports operating in Virtual Hierarchy (VH) >> mode.[1] >> >> CXL and PCIe Protocol Error handling have different requirements that >> necessitate a separate handling path. The AER service driver may try to >> recover PCIe uncorrectable non-fatal errors (UCE). The same recovery is not >> suitable for CXL PCIe Port devices because of potential for system memory >> corruption. Instead, CXL Protocol Error handling must use a kernel panic >> in the case of a fatal or non-fatal UCE. The AER driver's PCIe Protocol >> Error handling does not panic the kernel in response to a UCE. >> > Naive question: is a panic actually required if the memory is a userland > resource? > > The code in arch/x86/kernel/cpu/mce/core.c suggests we may not panic > if an uncorrectable error occurs in this fashion, but simply a SIGBUS. > > Unless this is down the wrong pipe - in which case disregard. > > I'm still digging through background on this patch set so I may be > barking up the wrong tree. > > ~Gregory The plan is to panic on any CXL device with uncorrectable errors regardless of where used. This is to avoid corruption. Terry