[PATCH v2 27/32] gpu: nova-core: vgpu: negotiate the GSP plugin RPC version

[Zhi Wang <zhiw@nvidia.com>]

The vGPU manager negotiates the RPC protocol with the booted GSP plugin
before sending configuration parameters.

Add the version-negotiation message ID and typed RPC submission.
Initialize the shared RPC buffers after the plugin reports ready, then
send the negotiation request.

Co-developed-by: Eliot Courtney <ecourtney@nvidia.com>
Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>
Signed-off-by: Zhi Wang <zhiw@nvidia.com>
---
 drivers/gpu/nova-core/vgpu/commands.rs        | 18 +++++++++++++++++-
 drivers/gpu/nova-core/vgpu/fw.rs              |  2 ++
 drivers/gpu/nova-core/vgpu/fw/commands.rs     |  9 +++++++++
 drivers/gpu/nova-core/vgpu/gsp_plugin_comm.rs |  5 +++--
 drivers/gpu/nova-core/vgpu/gsp_plugin_rpc.rs  | 11 ++++++-----
 drivers/gpu/nova-core/vgpu/instance.rs        | 10 ++++++++--
 6 files changed, 45 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/nova-core/vgpu/commands.rs b/drivers/gpu/nova-core/vgpu/commands.rs
index a2df36b901a8..abc85b0365f2 100644
--- a/drivers/gpu/nova-core/vgpu/commands.rs
+++ b/drivers/gpu/nova-core/vgpu/commands.rs
@@ -22,7 +22,13 @@
     },
 };
 
-use super::instance::Gfid;
+use crate::driver::Bar0;
+
+use super::{
+    fw::RpcMessage,
+    gsp_plugin_rpc::PluginRpc,
+    instance::Gfid, //
+};
 
 use super::fw::commands::VgpuPropertiesSchema;
 
@@ -144,3 +150,13 @@ pub(super) fn send_cleanup(
     dev_dbg!(dev, "cleanup: gfid={} done\n", gfid.0);
     Ok(())
 }
+
+/// Negotiate the host protocol with a bootloaded GSP plugin.
+pub(super) fn negotiate_plugin_version(
+    dev: &device::Device<device::Bound>,
+    bar0: Bar0<'_>,
+    gfid: Gfid,
+    rpc: &mut PluginRpc<'_, '_>,
+) -> Result {
+    rpc.rpc_call(dev, bar0, gfid, RpcMessage::VersionNegotiation, &[])
+}
diff --git a/drivers/gpu/nova-core/vgpu/fw.rs b/drivers/gpu/nova-core/vgpu/fw.rs
index 9925d5ccf71f..6cec92c9b505 100644
--- a/drivers/gpu/nova-core/vgpu/fw.rs
+++ b/drivers/gpu/nova-core/vgpu/fw.rs
@@ -27,6 +27,8 @@
     VGPU_CPU_GSP_VGPU_TASK_LOG_BUFF_REGION_SIZE, //
 };
 
+pub(super) use commands::RpcMessage;
+
 pub(super) const GMCAPI_CMD_QUERY_ASSIGNED_VF_VGPU_TYPE: u32 =
     bindings::GMCAPI_COMMANDS_GMCAPI_CMD_QUERY_ASSIGNED_VF_VGPU_TYPE;
 
diff --git a/drivers/gpu/nova-core/vgpu/fw/commands.rs b/drivers/gpu/nova-core/vgpu/fw/commands.rs
index 2e6518e2460b..b765d30a1d61 100644
--- a/drivers/gpu/nova-core/vgpu/fw/commands.rs
+++ b/drivers/gpu/nova-core/vgpu/fw/commands.rs
@@ -25,6 +25,15 @@
     Required, //
 };
 
+use super::bindings;
+
+/// Message types supported by the nova-core plugin RPC channel.
+#[derive(Clone, Copy)]
+#[repr(u32)]
+pub(in crate::vgpu) enum RpcMessage {
+    VersionNegotiation = bindings::MESSAGE_NV_VGPU_CPU_RPC_MSG_VERSION_NEGOTIATION,
+}
+
 bitfield! {
     pub(in crate::vgpu) struct Dbdf(u32) {
         2:0 function;
diff --git a/drivers/gpu/nova-core/vgpu/gsp_plugin_comm.rs b/drivers/gpu/nova-core/vgpu/gsp_plugin_comm.rs
index 20695929a58c..e385ecff43fa 100644
--- a/drivers/gpu/nova-core/vgpu/gsp_plugin_comm.rs
+++ b/drivers/gpu/nova-core/vgpu/gsp_plugin_comm.rs
@@ -18,6 +18,7 @@
     self,
     RawControlRegion,
     RawResponseRegion,
+    RpcMessage,
     RpcResponse, //
 };
 
@@ -337,7 +338,7 @@ pub(super) fn initialize(&self) -> Result {
     }
 
     /// Copy and publish one RPC request to firmware.
-    pub(super) fn submit(&self, message: u32, sequence: u32, data: &[u8]) -> Result {
+    pub(super) fn submit(&self, message: RpcMessage, sequence: u32, data: &[u8]) -> Result {
         if u64::try_from(data.len()).map_err(|_| EOVERFLOW)? > self.message.size() {
             return Err(E2BIG);
         }
@@ -352,7 +353,7 @@ pub(super) fn submit(&self, message: u32, sequence: u32, data: &[u8]) -> Result
         self.write_u32(
             &self.control,
             core::mem::offset_of!(RawControlRegion, __bindgen_anon_1.message_type),
-            message,
+            message as u32,
         )?;
         self.write_u32(
             &self.control,
diff --git a/drivers/gpu/nova-core/vgpu/gsp_plugin_rpc.rs b/drivers/gpu/nova-core/vgpu/gsp_plugin_rpc.rs
index bc5d576d8601..ff009f241c32 100644
--- a/drivers/gpu/nova-core/vgpu/gsp_plugin_rpc.rs
+++ b/drivers/gpu/nova-core/vgpu/gsp_plugin_rpc.rs
@@ -35,7 +35,10 @@
 };
 
 use super::{
-    fw::RpcResponse,
+    fw::{
+        RpcMessage,
+        RpcResponse, //
+    },
     gsp_plugin_comm::CommBufferRegion,
     instance::Gfid, //
 };
@@ -59,7 +62,6 @@ pub(super) fn comm(&self) -> &CommBufferRegion<'map, 'gpu> {
     }
 
     /// Initialize the control and response buffers for the first RPC.
-    #[expect(dead_code)]
     pub(super) fn init_rpc(&mut self) -> Result {
         self.comm.initialize()?;
         self.message_sequence = 0;
@@ -76,13 +78,12 @@ fn next_sequence(&self) -> u32 {
     }
 
     /// Write one RPC message, ring the VF doorbell, and wait for its response.
-    #[expect(dead_code)]
     pub(super) fn rpc_call(
         &mut self,
         dev: &device::Device<device::Bound>,
         bar0: Bar0<'_>,
         gfid: Gfid,
-        message_type: u32,
+        message_type: RpcMessage,
         data: &[u8],
     ) -> Result {
         let sequence = self.next_sequence();
@@ -93,7 +94,7 @@ pub(super) fn rpc_call(
             dev,
             "vGPU RPC: gfid={} type={} bytes={} sequence={}\n",
             gfid.0,
-            message_type,
+            message_type as u32,
             data.len(),
             sequence,
         );
diff --git a/drivers/gpu/nova-core/vgpu/instance.rs b/drivers/gpu/nova-core/vgpu/instance.rs
index 994b046802c1..a65b95d11f88 100644
--- a/drivers/gpu/nova-core/vgpu/instance.rs
+++ b/drivers/gpu/nova-core/vgpu/instance.rs
@@ -22,6 +22,7 @@
 };
 
 use crate::{
+    driver::Bar0,
     gpu::ChannelIdReservation,
     mm::{
         bar_user::BarUser,
@@ -41,6 +42,7 @@
 };
 
 use super::commands::{
+    negotiate_plugin_version,
     query_vgpu_properties,
     send_bootload,
     send_cleanup,
@@ -355,11 +357,12 @@ pub(super) fn allocate_instance(
         }
     }
 
-    /// Bootload the GSP plugin for a registered instance.
+    /// Boot the GSP plugin and negotiate its RPC version.
     pub(super) fn activate_instance(
         &mut self,
         dev: &device::Device<device::Bound>,
         cmdq: &Cmdq<'_>,
+        bar0: Bar0<'_>,
         gfid: Gfid,
         fifo_engine_list: &FifoEngineList,
     ) -> Result {
@@ -368,7 +371,10 @@ pub(super) fn activate_instance(
             .iter_mut()
             .find(|instance| instance.gfid == gfid)
             .ok_or(ENOENT)?;
-        instance.bootload(dev, cmdq, fifo_engine_list)
+        instance.bootload(dev, cmdq, fifo_engine_list)?;
+
+        instance.plugin_rpc.init_rpc()?;
+        negotiate_plugin_version(dev, bar0, gfid, &mut instance.plugin_rpc)
     }
 
     /// Stop the plugin and release the instance's firmware and host resources.