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client-ip=165.204.84.17; helo=satlexmb07.amd.com; pr=C Received: from satlexmb07.amd.com (165.204.84.17) by MWH0EPF000A6733.mail.protection.outlook.com (10.167.249.25) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9320.13 via Frontend Transport; Tue, 11 Nov 2025 21:43:45 +0000 Received: from ausbcheatha02.amd.com (10.180.168.240) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.17; Tue, 11 Nov 2025 13:43:44 -0800 From: Ben Cheatham To: CC: Subject: [PATCH 15/17] cxl/port: Bypass cache id for singleton cache devices Date: Tue, 11 Nov 2025 15:40:30 -0600 Message-ID: <20251111214032.8188-16-Benjamin.Cheatham@amd.com> X-Mailer: git-send-email 2.51.1 In-Reply-To: <20251111214032.8188-1-Benjamin.Cheatham@amd.com> References: <20251111214032.8188-1-Benjamin.Cheatham@amd.com> Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: satlexmb07.amd.com (10.181.42.216) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MWH0EPF000A6733:EE_|DS7PR12MB5838:EE_ X-MS-Office365-Filtering-Correlation-Id: d191e713-7a71-4d25-6873-08de216b63de X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700013|82310400026|376014|1800799024; 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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Nov 2025 21:43:45.2581 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: d191e713-7a71-4d25-6873-08de216b63de 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=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: MWH0EPF000A6733.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR12MB5838 The CXL cache id capability is required to have multiple CXL cache devices in the same virtual hierarchy (VH), but is not required if there is only a single cache device in the VH. If the host does not support the cache id capability and there is only a single device in the VH, skip allocation and programming of the capability. Signed-off-by: Ben Cheatham --- drivers/cxl/core/port.c | 1 + drivers/cxl/port.c | 34 ++++++++++++++++++++++++++++++++-- 2 files changed, 33 insertions(+), 2 deletions(-) diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c index e6e25a201ff9..3d9da6c3f672 100644 --- a/drivers/cxl/core/port.c +++ b/drivers/cxl/core/port.c @@ -617,6 +617,7 @@ struct cxl_port *parent_port_of(struct cxl_port *port) return NULL; return port->parent_dport->port; } +EXPORT_SYMBOL_NS_GPL(parent_port_of, "CXL"); static void unregister_port(void *_port) { diff --git a/drivers/cxl/port.c b/drivers/cxl/port.c index 4cecb731ec5b..68b6d9e34706 100644 --- a/drivers/cxl/port.c +++ b/drivers/cxl/port.c @@ -98,6 +98,28 @@ static int cxl_mem_endpoint_port_probe(struct cxl_port *port) return 0; } +static bool cxl_endpoint_is_only_cachedev(struct cxl_port *endpoint) +{ + unsigned long index; + struct cxl_ep *ep; + int cnt; + + for (struct cxl_port *port = endpoint; + !is_cxl_root(parent_port_of(port)); port = parent_port_of(port)) { + cnt = 0; + + xa_for_each(&port->endpoints, index, ep) { + if (is_cxl_cachedev(ep->ep)) + cnt++; + + if (cnt > 1) + return false; + } + } + + return true; +} + static void free_cache_id(void *data) { struct cxl_cachedev *cxlcd = data; @@ -113,8 +135,16 @@ static int cxl_cache_endpoint_port_probe(struct cxl_port *port) int rc, orig, id; rc = cxl_endpoint_map_cache_id_regs(port); - if (rc) - return rc; + if (rc) { + /* + * It's fine to not have cache id capabilities if this cachedev + * is the only one in its VH + */ + if (cxl_endpoint_is_only_cachedev(port)) + return 0; + + return -EBUSY; + } guard(mutex)(&cache_id_lock); rc = cxl_endpoint_get_cache_id(port, &orig); -- 2.51.1