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:
- Added documentation for the new property in DeviceTree bindings
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/
---
.../devicetree/bindings/bus/microsoft,vmbus.yaml | 8 ++++++++
drivers/hv/connection.c | 6 ++++--
drivers/hv/vmbus_drv.c | 13 +++++++++++++
3 files changed, 25 insertions(+), 2 deletions(-)
diff --git a/Documentation/devicetree/bindings/bus/microsoft,vmbus.yaml
b/Documentation/devicetree/bindings/bus/microsoft,vmbus.yaml
index 0bea4f5287ce..729ca6defec6 100644
--- a/Documentation/devicetree/bindings/bus/microsoft,vmbus.yaml
+++ b/Documentation/devicetree/bindings/bus/microsoft,vmbus.yaml
@@ -17,6 +17,14 @@ properties:
compatible:
const: microsoft,vmbus
+ microsoft,message-connection-id:
+ description:
+ VMBus message connection ID to be used for communication between
host and
+ guest. If not specified, defaults to
VMBUS_MESSAGE_CONNECTION_ID_4 for
+ protocol version VERSION_WIN10_V5 and above, or
VMBUS_MESSAGE_CONNECTION_ID
+ for older versions.
+ $ref: /schemas/types.yaml#/definitions/uint32
+
ranges: true
'#address-cells':
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index be490c598785..e0f38d799d06 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -99,12 +99,14 @@ 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
* bitwise OR it
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index c236081d0a87..d14d286671cc 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
