vgsp-gr r585: demand the fill's dropped pages through the pin channel (the staging-pin coverage class)

The r584 boot's matmul draw: GR-DEC push=0x20043be64 n_data=2 dropped=18
partial=1 stalled=1 -> the r543 argument defer expired -> r564 degenerate
refusal -> SW completion -> MATMUL bad=65536 csum=0. The dropped pages
(the client's staging buffers 0x71b662c00000/c40000/c80000,
0x7dd0cac00000, kind=a) had NO injected mapping: the host pin stream's
demand loop only parses "stalled VA #N: 0x..." lines, and the GRFILL-DROP
line format is invisible to it - so the fill's retries never saw pins and
the launch was SW-completed without running.

r585: svc_log_stalled_va() for each dropped page (up to the 4 detailed per
episode; the helper dedups per boot and the episode marker bounds the
rate). The host demand loop (<=3 s) then pushes the VA to the guest
scanner, whose pin lands inside the launch's bounded defer window on the
retry - the demand path that already heals every other unresolved-VA
class, now connected to the fill drops.

1 files changed, 20 insertions, 1 deletions

diff --git a/kernel/gsp_sema_service.c b/kernel/gsp_sema_service.c
index 6e0d88b..24cb034 100644
--- a/kernel/gsp_sema_service.c
+++ b/kernel/gsp_sema_service.c
@@ -20695,10 +20695,29 @@ static void svc_gr_data_fill(struct nv_vgpu_device *vgpu,
 			u32 dl;
 
 			svc_gr_drop_log_va = svc_fwd_req.gr_push_va;
-			for (dl = 0; dl < 4 && dl < dropped_pages; dl++)
+			for (dl = 0; dl < 4 && dl < dropped_pages; dl++) {
+				/*
+				 * r585: DEMAND the dropped pages through the
+				 * pin channel. The host pin stream parses the
+				 * "stalled VA #N: 0x..." lines (svc_log_stalled_va)
+				 * and pushes each VA to the guest scanner within
+				 * ~3 s, whose pin then lands inside the launch's
+				 * bounded argument-defer window - the r584 matmul
+				 * draw dropped 18 staging pages that were NEVER
+				 * demanded (the GRFILL-DROP line format is
+				 * invisible to the host's demand regex), the r543
+				 * defer window expired, and the r564 degenerate
+				 * refusal SW-completed a launch that wrote
+				 * nothing (MATMUL bad=65536 csum=0). One demand
+				 * per page per boot (svc_log_stalled_va dedups);
+				 * one episode per launch push VA (the marker
+				 * above).
+				 */
+				svc_log_stalled_va(drop_va[dl]);
 				pr_info("vgsp-gr: GRFILL-DROP va=0x%llx kind=%c idx=%u\n",
 					drop_va[dl], drop_kind[dl],
 					drop_idx[dl]);
+			}
 		}
 	}
 	if (svc_gr_data_stalled)