[PATCH v4 23/33] gpu: nova-core: Hopper/Blackwell: add FSP send/receive messaging

John Hubbard
2026-02-10T02:46:40Z

Add send_sync_fsp() which sends an MCTP/NVDM message to FSP and waits
for the response. This handles the low-level protocol details including
header validation, error checking, and timeout handling.

Cc: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
drivers/gpu/nova-core/falcon/fsp.rs | 3 -
drivers/gpu/nova-core/fsp.rs | 101 ++++++++++++++++++++++++++++
2 files changed, 101 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/nova-core/falcon/fsp.rs b/drivers/gpu/nova-core/falcon/fsp.rs
index 51dae900267f..08b382a32cc0 100644
--- a/drivers/gpu/nova-core/falcon/fsp.rs
+++ b/drivers/gpu/nova-core/falcon/fsp.rs
@@ -90,7 +90,6 @@ 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();
@@ -113,7 +112,6 @@ 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);
@@ -145,7 +143,6 @@ 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 fca03e25134d..479b97eed7bd 100644
--- a/drivers/gpu/nova-core/fsp.rs
+++ b/drivers/gpu/nova-core/fsp.rs
@@ -22,6 +22,9 @@

use crate::regs::FSP_BOOT_COMPLETE_SUCCESS;

+/// FSP message timeout in milliseconds.
+const FSP_MSG_TIMEOUT_MS: i64 = 2000;
+
/// FSP secure boot completion timeout in milliseconds.
const FSP_SECURE_BOOT_TIMEOUT_MS: i64 = 4000;

@@ -311,4 +314,102 @@ pub(crate) fn extract_fmc_signatures_static(

Ok(signatures)
}
+
+ /// Send message to FSP and wait for response.
+ fn send_sync_fsp(
+ dev: &device::Device<device::Bound>,
+ bar: &crate::driver::Bar0,
+ fsp_falcon: &crate::falcon::Falcon<crate::falcon::fsp::Fsp>,
+ nvdm_type: u32,
+ packet: &[u8],
+ ) -> Result<()> {
+ // Send message
+ fsp_falcon.send_msg(bar, packet)?;
+
+ // Wait for response
+ 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::ZERO,
+ timeout,
+ )
+ .map_err(|_| {
+ dev_err!(dev, "FSP response timeout\n");
+ ETIMEDOUT
+ })?;
+
+ // Receive response
+ 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)?;
+
+ // Parse response
+ 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)?;
+
+ // Copy packed struct fields to avoid alignment issues
+ let mctp_header = response.mctp_header;
+ let nvdm_header = response.nvdm_header;
+ let command_nvdm_type = response.response.command_nvdm_type;
+ let error_code = response.response.error_code;
+
+ // Validate MCTP header
+ let mctp_som = (mctp_header >> 31) & 1;
+ let mctp_eom = (mctp_header >> 30) & 1;
+ if mctp_som != 1 || mctp_eom != 1 {
+ dev_err!(
+ dev,
+ "Unexpected MCTP header in FSP reply: {:#x}\n",
+ mctp_header
+ );
+ return Err(EIO);
+ }
+
+ // Validate NVDM header
+ let nvdm_msg_type = nvdm_header & 0x7f;
+ let nvdm_vendor_id = (nvdm_header >> 8) & 0xffff;
+ let nvdm_type_resp = (nvdm_header >> 24) & 0xff;
+
+ if nvdm_msg_type != mctp::MSG_TYPE_VENDOR_PCI
+ || nvdm_vendor_id != mctp::VENDOR_ID_NV
+ || nvdm_type_resp != mctp::NVDM_TYPE_FSP_RESPONSE
+ {
+ dev_err!(
+ dev,
+ "Unexpected NVDM header in FSP reply: {:#x}\n",
+ nvdm_header
+ );
+ return Err(EIO);
+ }
+
+ // Check command type matches
+ if command_nvdm_type != nvdm_type {
+ dev_err!(
+ dev,
+ "Expected NVDM type {:#x} in reply, got {:#x}\n",
+ nvdm_type,
+ command_nvdm_type
+ );
+ return Err(EIO);
+ }
+
+ // Check for errors
+ if error_code != 0 {
+ dev_err!(
+ dev,
+ "NVDM command {:#x} failed with error {:#x}\n",
+ nvdm_type,
+ error_code
+ );
+ return Err(EIO);
+ }
+
+ Ok(())
+ }
}
--
2.53.0