The connection-id determines which hypervisor communication channel the guest should use to talk to the VMBus host. This patch adds support to read this value from the DeviceTree where it exists as a property under the vmbus node with the compatible ID "microsoft,message-connection-id". The property name follows the format <vendor>,<field> where "vendor": "microsoft" and "field": "message-connection-id"
Reading from DeviceTree allows platforms to specify their preferred communication channel, making it more flexible. If the property is not found in the DeviceTree, use the default connection ID (VMBUS_MESSAGE_CONNECTION_ID or VMBUS_MESSAGE_CONNECTION_ID_4 based on protocol version). Signed-off-by: Hardik Garg <har...@linux.microsoft.com> --- v3: https://lore.kernel.org/all/6a92ca86-ad6b-4d49-af6e-1ed7651b8...@linux.microsoft.com v2: https://lore.kernel.org/all/096edaf7-cc90-42b6-aff4-c5f088574...@linux.microsoft.com v1: https://lore.kernel.org/all/6acee4bf-cb04-43b9-9476-e8d811d26...@linux.microsoft.com --- drivers/hv/connection.c | 6 ++++-- drivers/hv/vmbus_drv.c | 13 +++++++++++++ 2 files changed, 17 insertions(+), 2 deletions(-) diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c index be490c598785..15d2b652783d 100644 --- a/drivers/hv/connection.c +++ b/drivers/hv/connection.c @@ -99,11 +99,13 @@ int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version) if (version >= VERSION_WIN10_V5) { msg->msg_sint = VMBUS_MESSAGE_SINT; msg->msg_vtl = ms_hyperv.vtl; - vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID_4; } else { msg->interrupt_page = virt_to_phys(vmbus_connection.int_page); - vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID; } + /* Set default connection ID if not provided via DeviceTree */ + if (!vmbus_connection.msg_conn_id) + vmbus_connection.msg_conn_id = (version >= VERSION_WIN10_V5) ? + VMBUS_MESSAGE_CONNECTION_ID_4 : VMBUS_MESSAGE_CONNECTION_ID; /* * shared_gpa_boundary is zero in non-SNP VMs, so it's safe to always diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c index c236081d0a87..b78d5499e4bc 100644 --- a/drivers/hv/vmbus_drv.c +++ b/drivers/hv/vmbus_drv.c @@ -2541,10 +2541,23 @@ static int vmbus_device_add(struct platform_device *pdev) struct of_range range; struct of_range_parser parser; struct device_node *np = pdev->dev.of_node; + unsigned int conn_id; int ret; vmbus_root_device = &pdev->dev; + /* + * Read connection ID from DeviceTree. The property name follows the + * format <vendor>,<field> where: + * - vendor: "microsoft" + * - field: "message-connection-id" + */ + ret = of_property_read_u32(np, "microsoft,message-connection-id", &conn_id); + if (!ret) { + pr_info("VMBus message connection ID: %u\n", conn_id); + vmbus_connection.msg_conn_id = conn_id; + } + ret = of_range_parser_init(&parser, np); if (ret) return ret; -- 2.40.4
