vgsp: accept wrapped FB USERD latches and dedup direct channel event postsHEADmaster

1 files changed, 53 insertions, 4 deletions

diff --git a/kernel/gsp_sema_service.c b/kernel/gsp_sema_service.c
index 7e389f8..96e135b 100644
--- a/kernel/gsp_sema_service.c
+++ b/kernel/gsp_sema_service.c
@@ -43835,6 +43835,35 @@ static void svc_gr_util_sweep(struct nv_vgpu_device *vgpu,
 	svc_gr_util_sweep_n(vgpu, ch, 0);
 }
 
+/*
+ * Wrap-aware PUT progress for the speculative latch.
+ *
+ * A USERD adopted by the FB/VRAM shape scan carries GPFIFO ring indices in
+ * [0, entries] (the shape gate rejects put > entries; `entries` is the
+ * wrapped/empty value). Such a producer legitimately wraps entries -> 0:
+ * h=0x1000013 (ent=65536, latch=65536) later reads put=12, and the raw
+ * `put > latch` judge saw a decrease, rejected the live block and cleared
+ * userd_ok - the X/DDX channel then waited forever in "Failed to idle
+ * DMA". For that class compare modulo entries (entries is a power of two):
+ * a step of 1..entries/2 is forward progress; anything else (backward
+ * jump or more than half the ring) keeps the old reject path.
+ *
+ * Channels whose PUT is a free-running counter keep the raw comparison:
+ * the guest-RAM scan (SYS aperture, gr_ram_ring) explicitly admits puts
+ * far above entries (measured put=12 with entries=2 and put=16 with
+ * entries=32768), the kick family (0xbfef00xx) authors its own free-
+ * running count, and a non-power-of-two ring has no usable mask. A
+ * one-slot ring is excluded too: every put aliases, so there is no
+ * modulo progress to measure.
+ */
+static bool svc_userd_put_wrap(const struct svc_channel *ch)
+{
+	u32 entries = ch->gpfifo_entries;
+
+	return entries >= 2 && !(entries & (entries - 1)) &&
+	       ch->userd_as == SVC_APERTURE_FB && !svc_kick_family(ch);
+}
+
 static void svc_pump_channels(struct nv_vgpu_device *vgpu)
 {
 	if (svc_pdb_disc_pending) {
@@ -44665,6 +44694,12 @@ static void svc_pump_channels(struct nv_vgpu_device *vgpu)
 		    (!ch->gr_ram_userd_confirmed ||
 		     (kfam && put < ch->gr_ram_userd_latch_put))) {
 			bool stepped;
+			bool wrap = svc_userd_put_wrap(ch);
+			u32 wstep = wrap ?
+				(put - ch->gr_ram_userd_latch_put) &
+				(ch->gpfifo_entries - 1) : 0;
+			bool moved = wrap ? wstep != 0 :
+				     put != ch->gr_ram_userd_latch_put;
 
 			if (!ch->gr_ram_userd_latch_at)
 				ch->gr_ram_userd_latch_at = jiffies;
@@ -44678,10 +44713,25 @@ static void svc_pump_channels(struct nv_vgpu_device *vgpu)
 			 * at ~10 Hz. A forward jump is not evidence of a
 			 * stale latch: only a decrease (wrong actor / reused
 			 * block) or the 15 s no-advance bound is.
+			 *
+			 * WRAP-FIX: for a ring-index PUT (FB shape scan,
+			 * power-of-two entries) "forward" is modulo entries.
+			 * h=0x1000013 legitimately wrapped 65536 -> 12 and
+			 * the raw compare rejected the live block; see
+			 * svc_userd_put_wrap().
 			 */
-			stepped = put > ch->gr_ram_userd_latch_put;
+			stepped = wrap ?
+				(wstep && wstep <= ch->gpfifo_entries / 2) :
+				put > ch->gr_ram_userd_latch_put;
 			if (stepped) {
 				ch->gr_ram_userd_confirmed = true;
+				if (wrap &&
+				    put < ch->gr_ram_userd_latch_put)
+					pr_info_ratelimited("sema-chan: GR USERD h=0x%x pa=0x%llx speculative latch wrap accepted (put %u latch %u ent %u step %u)\n",
+						ch->h_object, ch->userd_pa,
+						put,
+						ch->gr_ram_userd_latch_put,
+						ch->gpfifo_entries, wstep);
 				pr_info("sema-chan: GR USERD h=0x%x pa=0x%llx speculative latch CONFIRMED (put %u -> %u)\n",
 					ch->h_object, ch->userd_pa,
 					ch->gr_ram_userd_latch_put, put);
@@ -44718,7 +44768,7 @@ static void svc_pump_channels(struct nv_vgpu_device *vgpu)
 				}
 				ch->gr_ram_userd_latch_put = put;
 				ch->gr_ram_userd_latch_at = jiffies;
-			} else if (put != ch->gr_ram_userd_latch_put ||
+			} else if (moved ||
 				   time_after(jiffies,
 					      ch->gr_ram_userd_latch_at +
 					      msecs_to_jiffies(15000))) {
@@ -44728,8 +44778,7 @@ static void svc_pump_channels(struct nv_vgpu_device *vgpu)
 				pr_info("sema-chan: GR USERD h=0x%x pa=0x%llx speculative latch REJECTED (put=%u latch=%u%s)\n",
 					ch->h_object, ch->userd_pa, put,
 					ch->gr_ram_userd_latch_put,
-					put != ch->gr_ram_userd_latch_put ?
-						"" : " no advance in 15 s");
+					moved ? "" : " no advance in 15 s");
 				/*
 				 * SESSION 153-CONT-5: one stale window must not
 				 * kill the pipeline. Remember the rejected