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client-ip=165.204.84.17; helo=satlexmb08.amd.com; pr=C Received: from satlexmb08.amd.com (165.204.84.17) by SJ1PEPF00002321.mail.protection.outlook.com (10.167.242.91) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.406.5 via Frontend Transport; Mon, 7 Sep 2026 16:06:47 +0000 Received: from Satlexmb09.amd.com (10.181.42.218) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.46; Mon, 7 Sep 2026 11:06:46 -0500 Received: from sriov-SYS-7048GR-TR.xilinx.com (10.180.168.240) by satlexmb09.amd.com (10.181.42.218) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.46; Mon, 7 Sep 2026 11:06:44 -0500 From: Nikola Prica To: CC: , , , , , , , , Nikola Prica Subject: [PATCH v2] PCI: Accept AtomicOps already enabled by the hypervisor Date: Mon, 7 Sep 2026 18:17:01 +0200 Message-ID: <20260907161701.454364-1-nikprica@amd.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260903121217.23F751F000E9@smtp.kernel.org> References: <20260903121217.23F751F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: satlexmb08.amd.com (10.181.42.217) To satlexmb09.amd.com (10.181.42.218) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ1PEPF00002321:EE_|IA0PPF170E97DF1:EE_ X-MS-Office365-Filtering-Correlation-Id: 47f584af-eea6-4aa5-e0a3-08df0cfa04e8 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|36860700016|1800799024|23010399003|376014|10067099003|6133799003|56012099006|5023799004|11063799006|18002099003|22082099003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: y7bcK8PmPws5dIK1k291oPnltcvMnoWUvb92Q4ARVnwApCDvUc8okZeeBYQDhQu9W2CIdTV5Gu0uWNiND1xuYO0An9QoUnuI+jpL7TrQM81xr1hlhcVDD/c3WTZztSs90ANzPeG9iYVJ8C4KriPYl3cBNwduwLrtqdqypOEEOKOYs3bjMKE3rCbD1ojpl6nso0EcVGr+/Mtd0TsjhEqPzN14KSIVTVJel7lkCW/A6VcWGihuhEpxuee/P3Qsni8dQuPRVDx1QBpiIYHirArinM0VxlIkX+1b2JWLrIYwSKeNhemtOR91EOm8yzEWSOXdAGwxmsReDziEJR520Wi42qQs6n3mT0JVyxR6Sp+qGd/LzdEKZzf+SJHhdWbk536JbhOjD1pkTNWzrQiwOl9womN3CMCVbFM08lr6dibm/iFIgVFAqIVx1G76zCwqBVXa X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Sep 2026 16:06:47.3000 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 47f584af-eea6-4aa5-e0a3-08df0cfa04e8 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb08.amd.com] X-MS-Exchange-CrossTenant-AuthSource: SJ1PEPF00002321.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA0PPF170E97DF1 From: Nikola Prica pci_enable_atomic_ops_to_root() currently fails when no root port is visible. That is common in passthrough guests (ESXi, Hyper-V): the endpoint is assigned to the VM, but the guest topology has no root port above it. In those setups the hypervisor may already have enabled AtomicOp requester enable on the device. If PCI_EXP_DEVCTL2_ATOMIC_REQ is set, treat AtomicOps as already enabled and return success instead of failing the Root Port walk. Signed-off-by: Nikola Prica --- Changes in v2: - Be more strict and only apply logic in headless device case. drivers/pci/pci.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index b2879a6be5f8..62729ade496f 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -3769,8 +3769,18 @@ int pci_enable_atomic_ops_to_root(struct pci_dev *dev, u32 cap_mask) } root = pcie_find_root_port(dev); - if (!root) + if (!root) { + /* + * A hypervisor may expose a headless topology with no + * visible root port. If it has already set AtomicOp + * Requester Enable, there is nothing more to do. + */ + pcie_capability_read_dword(dev, PCI_EXP_DEVCTL2, &ctl2); + if (ctl2 & PCI_EXP_DEVCTL2_ATOMIC_REQ) + return 0; + return -EINVAL; + } pcie_capability_read_dword(root, PCI_EXP_DEVCAP2, &cap); if ((cap & cap_mask) != cap_mask) -- 2.34.1