drm/xe/guc: Let xe_guc_ct_send_locked() callers reserve G2H credit

Browse source

Commit d4a7e16117 ("drm/xe: batch CT pagefault acks with periodic
flush") added a defer_flush argument to xe_guc_ct_send_locked(). At the
same time it dropped the g2h_len and num_g2h arguments, which had no
in-tree users, and hardcoded a zero G2H reservation.

That leaves no way to send an H2G that expects a G2H reply while
already holding ct->lock. The G2H receive path (parse_g2h_event() and
g2h_fast_path()) releases credit unconditionally for replies such as
DEREGISTER_CONTEXT_DONE, SCHED_CONTEXT_MODE_DONE and
TLB_INVALIDATION_DONE. If the credit was never reserved,
__g2h_release_space() reports an "Invalid G2H release" and marks the CT
dead with CT_DEAD_G2H_RELEASE.

Replacing two u32 arguments with a bool also means a caller written
against the old signature can silently change meaning when the two
reservation arguments get merged into one: the call still compiles,
still sends the H2G, and loses only the reservation.

Add g2h_len and num_g2h back, ahead of defer_flush, so that the
function matches xe_guc_ct_send() and forwards both values to
guc_ct_send_locked(). The kernel-doc now says when a reservation is
required and that a non-zero reservation must not be made from a G2H
handler, because waiting for credit can dequeue G2H inline.

The only existing caller, the pagefault ack path, does not expect a
reply. It passes 0, 0 and behaves exactly as before.

Cc: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Sujaritha Sundaresan <sujaritha.sundaresan@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patch.msgid.link/20260929050342.221789-1-sujaritha.sundaresan@intel.com
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

...

This commit is contained in:

Sujaritha Sundaresan 2026-09-29 10:33:42 +05:30 • committed by Rodrigo Vivi

parent 34d088dfb8

commit 367130639b

No known key found for this signature in database

GPG key ID: FA625F640EEB13CA

3 changed files with 18 additions and 4 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

17

drivers/gpu/drm/xe/xe_guc_ct.c

View file

2

drivers/gpu/drm/xe/xe_guc_ct.h

View file

3

drivers/gpu/drm/xe/xe_guc_pagefault.c

View file