[PATCH v9 21/31] gpu: nova-core: Hopper/Blackwell: add FSP send/receive messaging

John Hubbard
2026-03-26T01:39:45Z

Add send_sync_fsp() which sends an MCTP/NVDM message to FSP and waits
for the response. Response validation uses the typed MctpHeader and
NvdmHeader wrappers from the previous commit.

A MessageToFsp trait provides the NVDM type constant for each message
struct, so send_sync_fsp() can verify that the response matches the
request.

Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
drivers/gpu/nova-core/falcon/fsp.rs | 3 -
drivers/gpu/nova-core/fsp.rs | 123 ++++++++++++++++++++++++++++
2 files changed, 123 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/nova-core/falcon/fsp.rs b/drivers/gpu/nova-core/falcon/fsp.rs
index faf923246ae9..1dcfd155b99c 100644
--- a/drivers/gpu/nova-core/falcon/fsp.rs
+++ b/drivers/gpu/nova-core/falcon/fsp.rs
@@ -150,7 +150,6 @@ pub(crate) fn read_emem(&self, bar: &Bar0, offset: u32, data: &mut [u8]) -> Resu
///
/// The FSP message queue is not circular - pointers are reset to 0 after each
/// message exchange, so `tail >= head` is always true when data is present.
- #[expect(unused)]
pub(crate) fn poll_msgq(&self, bar: &Bar0) -> u32 {
let head = regs::NV_PFSP_MSGQ_HEAD::read(bar).address();
let tail = regs::NV_PFSP_MSGQ_TAIL::read(bar).address();
@@ -173,7 +172,6 @@ pub(crate) fn poll_msgq(&self, bar: &Bar0) -> u32 {
///
/// # Returns
/// `Ok(())` on success, `Err(EINVAL)` if packet is empty or not 4-byte aligned
- #[expect(unused)]
pub(crate) fn send_msg(&self, bar: &Bar0, packet: &[u8]) -> Result {
if packet.is_empty() {
return Err(EINVAL);
@@ -205,7 +203,6 @@ pub(crate) fn send_msg(&self, bar: &Bar0, packet: &[u8]) -> Result {
///
/// # Returns
/// `Ok(bytes_read)` on success, `Err(EINVAL)` if size is 0, exceeds buffer, or not aligned
- #[expect(unused)]
pub(crate) fn recv_msg(&self, bar: &Bar0, buffer: &mut [u8], size: usize) -> Result<usize> {
if size == 0 || size > buffer.len() {
return Err(EINVAL);
diff --git a/drivers/gpu/nova-core/fsp.rs b/drivers/gpu/nova-core/fsp.rs
index bbf89c70a425..931d806c3db8 100644
--- a/drivers/gpu/nova-core/fsp.rs
+++ b/drivers/gpu/nova-core/fsp.rs
@@ -19,6 +19,15 @@

use crate::regs;

+use crate::mctp::{
+ MctpHeader,
+ NvdmHeader,
+ NvdmType, //
+};
+
+/// FSP message timeout in milliseconds.
+const FSP_MSG_TIMEOUT_MS: i64 = 2000;
+
/// FSP secure boot completion timeout in milliseconds.
///
/// GB20x requires a longer timeout than Hopper/GB10x.
@@ -124,6 +133,37 @@ pub(crate) struct FmcSignatures {
public_key: [u8; FSP_PKEY_SIZE],
signature: [u8; FSP_SIG_SIZE],
}
+
+/// FSP Command Response payload structure.
+/// NVDM_PAYLOAD_COMMAND_RESPONSE structure.
+#[repr(C, packed)]
+#[derive(Clone, Copy)]
+struct NvdmPayloadCommandResponse {
+ task_id: u32,
+ command_nvdm_type: u32,
+ error_code: u32,
+}
+
+/// Complete FSP response structure with MCTP and NVDM headers.
+#[repr(C, packed)]
+#[derive(Clone, Copy)]
+struct FspResponse {
+ mctp_header: u32,
+ nvdm_header: u32,
+ response: NvdmPayloadCommandResponse,
+}
+
+// SAFETY: FspResponse is a packed C struct with only integral fields.
+unsafe impl FromBytes for FspResponse {}
+
+/// Trait implemented by types representing a message to send to FSP.
+///
+/// This provides [`Fsp::send_sync_fsp`] with the information it needs to send
+/// a given message, following the same pattern as GSP's `CommandToGsp`.
+pub(crate) trait MessageToFsp: AsBytes {
+ /// NVDM type identifying this message to FSP.
+ const NVDM_TYPE: u32;
+}
/// FSP interface for Hopper/Blackwell GPUs.
pub(crate) struct Fsp;

@@ -224,4 +264,87 @@ pub(crate) fn extract_fmc_signatures(

Ok(signatures)
}
+
+ /// Send message to FSP and wait for response.
+ #[expect(dead_code)]
+ fn send_sync_fsp<M>(
+ dev: &device::Device<device::Bound>,
+ bar: &crate::driver::Bar0,
+ fsp_falcon: &crate::falcon::Falcon<crate::falcon::fsp::Fsp>,
+ msg: &M,
+ ) -> Result
+ where
+ M: MessageToFsp,
+ {
+ fsp_falcon.send_msg(bar, msg.as_bytes())?;
+
+ let timeout = Delta::from_millis(FSP_MSG_TIMEOUT_MS);
+ let packet_size = read_poll_timeout(
+ || Ok(fsp_falcon.poll_msgq(bar)),
+ |&size| size > 0,
+ Delta::from_millis(10),
+ timeout,
+ )
+ .map_err(|_| {
+ dev_err!(dev, "FSP response timeout\n");
+ ETIMEDOUT
+ })?;
+
+ let packet_size = packet_size as usize;
+ let mut response_buf = KVec::<u8>::new();
+ response_buf.resize(packet_size, 0, GFP_KERNEL)?;
+ fsp_falcon.recv_msg(bar, &mut response_buf, packet_size)?;
+
+ if response_buf.len() < core::mem::size_of::<FspResponse>() {
+ dev_err!(dev, "FSP response too small: {}\n", response_buf.len());
+ return Err(EIO);
+ }
+
+ let response = FspResponse::from_bytes(&response_buf[..]).ok_or(EIO)?;
+
+ let mctp_header: MctpHeader = response.mctp_header.into();
+ let nvdm_header: NvdmHeader = response.nvdm_header.into();
+ let command_nvdm_type = response.response.command_nvdm_type;
+ let error_code = response.response.error_code;
+
+ if !mctp_header.is_single_packet() {
+ dev_err!(
+ dev,
+ "Unexpected MCTP header in FSP reply: {:#x}\n",
+ mctp_header.raw()
+ );
+ return Err(EIO);
+ }
+
+ if !nvdm_header.validate(NvdmType::FspResponse) {
+ dev_err!(
+ dev,
+ "Unexpected NVDM header in FSP reply: {:#x}\n",
+ nvdm_header.raw()
+ );
+ return Err(EIO);
+ }
+
+ if command_nvdm_type != M::NVDM_TYPE {
+ dev_err!(
+ dev,
+ "Expected NVDM type {:#x} in reply, got {:#x}\n",
+ M::NVDM_TYPE,
+ command_nvdm_type
+ );
+ return Err(EIO);
+ }
+
+ if error_code != 0 {
+ dev_err!(
+ dev,
+ "NVDM command {:#x} failed with error {:#x}\n",
+ M::NVDM_TYPE,
+ error_code
+ );
+ return Err(EIO);
+ }
+
+ Ok(())
+ }
}
--
2.53.0