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b=vQDBWElerDBbvdpTCBaCjoF9Ehi1Uw8RiPEYQ2w08NPhGSsMvintWCVXu+PNGBDIL8YMiSa2za3ABF081MlzkZDPNLqUkF0qckIJsDa99jiL3IW9ay/FU0pherXC5ridD/+axw6b5BOBllleiOpBqsOG3w/40UjeQQQia9YOQyE= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from DM4PR12MB6254.namprd12.prod.outlook.com (2603:10b6:8:a5::17) by CY8PR12MB7435.namprd12.prod.outlook.com (2603:10b6:930:51::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.181.15; Wed, 15 Jul 2026 15:14:10 +0000 Received: from DM4PR12MB6254.namprd12.prod.outlook.com ([fe80::8211:9b5a:99d2:ffa1]) by DM4PR12MB6254.namprd12.prod.outlook.com ([fe80::8211:9b5a:99d2:ffa1%6]) with mapi id 15.21.0223.008; Wed, 15 Jul 2026 15:14:10 +0000 Message-ID: <129c9445-2b65-4052-a484-136f0641c3a4@amd.com> Date: Wed, 15 Jul 2026 16:14:04 +0100 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v9 00/11] PCI/CXL: Add CXL reset support for Type 2 devices Content-Language: en-US To: Srirangan Madhavan , Alison Schofield , Bjorn Helgaas , Dan Williams , Dave Jiang , Davidlohr Bueso , Jonathan Cameron , Vishal Verma , linux-cxl@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Alex Williamson , vsethi@nvidia.com, alwilliamson@nvidia.com, Dan Williams , Sai Yashwanth Reddy Kancherla , Vishal Aslot , Manish Honap , Jiandi An , Richard Cheng , linux-tegra@vger.kernel.org References: <20260709010304.680422-1-smadhavan@nvidia.com> From: Alejandro Lucero Palau In-Reply-To: <20260709010304.680422-1-smadhavan@nvidia.com> Content-Type: text/plain; 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The reset sequence follows the CXL 4.0 > specification [1], including CXL.cache disable, optional cache > writeback, CXL Reset initiation, ResetComplete polling, and ResetError > reporting. Hi Srirangan, I'm working on understanding all the implications in this patchset, and I have to say my mind is on adding multipf support to Type2 drivers, with a RFC coming soon to the list. Some comments below. Thanks. > The userspace ABI is the existing PCI reset interface: > > /sys/bus/pci/devices/.../reset_method > /sys/bus/pci/devices/.../reset Not sure if this will be available in any device PFs, but I think it should only be available for PF0 as the specs define this function as the one having the CXL DVSEC. In any case, the reset will only be possible if PF0 is not attached to the Type2 driver and therefore the memdev is not there. With the multipf support that will also be the case as any none PF0 device will rely on PF0 CXL driver initialization and if PF0 is detached from the driver, so will it be for non PF0 devices. Note this is not the same than the "Non-CXL Function Map DVSEC" you are checking later on. > > The CPU cache invalidation step depends on > cpu_cache_invalidate_memregion() support for the affected address ranges. > If no runtime provider is available, the kernel emits a warning and > continues after the affected HDM ranges have been reserved. Because no memdev should be there this step should not be necessary. Maybe as a sanity check.