vgsp: mode 35 m64 - forced module-sem release discriminant + fallback poll fix + post-mortem dumps

m63 (E2 lane enable) got the forwarded QMD into SKED: CWD_TABLE_0 left the
cold value, CWD_TABLE_1 carried the QMD id (0x1070), SKED_ACTIVITY fired,
FECS_CURRENT_CTX showed V7's instance with VALID=1 - but the release write
never landed (relw=5) and no engine fault is logged. m64 discriminates
'engine completed but the shadow release was lost' from 'engine never
completed': param gsp_phys_rmcall_gr_rel_mod=1 forces QMD release0 to the
module window-0 semaphore with a distinct payload (0x600df00d) and polls the
SEM chunk. Also fixes the latent fallback (it set no poll source, so a
module-sem release could never complete) and dumps the full QMD w2..w15 +
the guest release page words in the post-mortem.

1 files changed, 22 insertions, 0 deletions

diff --git a/kernel/gsp_phys_gpu.c b/kernel/gsp_phys_gpu.c
index 974100a..f323c6c 100644
--- a/kernel/gsp_phys_gpu.c
+++ b/kernel/gsp_phys_gpu.c
@@ -704,6 +704,28 @@ int gsp_phys_rmcall_gr_qmdwin_value(void)
 EXPORT_SYMBOL_GPL(gsp_phys_rmcall_gr_qmdwin_value);
 
 /*
+ * m64 forced module-semaphore release (gsp_phys_rmcall_gr_rel_mod; default 0).
+ * When set, a forwarded GR launch ignores the resolved guest release page and
+ * points QMD release0 at the module window-0 semaphore VA
+ * (GSP_PHYS_RMCALL_VA_SEM), which the host polls at the SEM chunk's host VA.
+ * Discriminant for "engine completed but the shadow release write was lost"
+ * vs "engine never completed": with the module release, a completed QMD is
+ * always observable. Also makes the existing module-release fallback
+ * observable (it previously set no poll source, so it could never complete).
+ */
+static int gsp_phys_rmcall_gr_rel_mod_param;
+module_param_named(gsp_phys_rmcall_gr_rel_mod,
+		   gsp_phys_rmcall_gr_rel_mod_param, int, 0644);
+MODULE_PARM_DESC(gsp_phys_rmcall_gr_rel_mod,
+		 "Force the forwarded GR QMD release0 to the module semaphore (default 0; 1 = m64 engine-completion discriminant)");
+
+int gsp_phys_rmcall_gr_rel_mod_value(void)
+{
+	return gsp_phys_rmcall_gr_rel_mod_param;
+}
+EXPORT_SYMBOL_GPL(gsp_phys_rmcall_gr_rel_mod_value);
+
+/*
  * Ladder VAS ownership selector (gsp_phys_rmcall_vas_shared; default 0).
  * The H1 GR promote wall is a direct consequence of the ladder's
  * externally-owned FERMI_VASPACE_A: with IS_EXTERNALLY_OWNED the RM treats