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gpu: nova-core: fsp: catch bogus queue pointer issues

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Currently, `poll_msgq` will report a message of size 4 if the queue
pointers are broken. It's easy to catch this if it occurs, so have
`poll_msgq` return an error in this case.

Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Link: https://patch.msgid.link/20260703-blackwell-fixes-v2-2-8e3d8bc32bb9@nvidia.com
[acourbot: explicitly mention the error, add paragraph separator.]
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
This commit is contained in:
Eliot Courtney 2026-07-03 19:22:06 +09:00 committed by Alexandre Courbot
parent 5f52374107
commit ed33ea9390
1 changed files with 10 additions and 6 deletions
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16
drivers/gpu/nova-core/falcon/fsp.rs
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@ -111,18 +111,22 @@ fn read_emem(&mut self, data: &mut [u8]) -> Result {
///
/// Returns the size of available data in bytes, or 0 if no data is available.
///
/// Returns [`EIO`] if the queue pointers are bogus (`tail < head`).
///
/// 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.
fn poll_msgq(&self) -> u32 {
fn poll_msgq(&self) -> Result<u32> {
let head = self.bar.read(regs::NV_PFSP_MSGQ_HEAD::at(0)).val();
let tail = self.bar.read(regs::NV_PFSP_MSGQ_TAIL::at(0)).val();
if head == tail {
return 0;
Ok(0)
} else {
// TAIL points at the last DWORD written, so the size is `tail - head + 4`.
tail.checked_sub(head)
.and_then(|delta| delta.checked_add(4))
.ok_or(EIO)
}
// TAIL points at last DWORD written, so add 4 to get total size.
tail.saturating_sub(head).saturating_add(4)
}
/// Writes `packet` to FSP EMEM and updates the queue pointers to notify FSP.
@ -156,7 +160,7 @@ pub(crate) fn send_msg(&mut self, packet: &[u8]) -> Result {
/// memory allocation error occurred.
pub(crate) fn recv_msg(&mut self) -> Result<KVec<u8>> {
let msg_size = read_poll_timeout(
|| Ok(self.poll_msgq()),
|| self.poll_msgq(),
|&size| size > 0,
Delta::from_millis(10),
Delta::from_millis(FSP_MSG_TIMEOUT_MS),