vgsp: perf tracing + map-verified rescue + us RPC quanta (session 148)

- sema_trace_h + sema-perf logs: per-second channel state (put/last/armed/
  counter) and publish-gate reasons, plus maprescue attempt outcomes.
  Instrument added after window tuning failed to move the 22.4 s/frame
  glxgears cadence; it located the real blocker in one run.
- svc_rescue_push_page: content-verified full-chain map rescue (works for
  GR channels, whose rescue was previously refused outright).
- gsp_phys_booter: RPC reply waits now usleep_range(150-350us) instead of
  msleep(5) (termbin review suggestion, in-tree constant verified; no
  FPS change measured, kept as correctness-neutral latency reduction).

Evidence: r843-r847 dmesg_live logs; measured constant 22.4 s/frame for
glxgears across all param windows (grace/poll/first-poll), showing the
pacer is elsewhere - traced to client pushbuffer pages (va=0x3f06270-class)
failing svc_lookup (-ENOENT) while the client is alive.

1 files changed, 22 insertions, 8 deletions

diff --git a/kernel/gsp_phys_booter.c b/kernel/gsp_phys_booter.c
index 2f3202e..534a443 100644
--- a/kernel/gsp_phys_booter.c
+++ b/kernel/gsp_phys_booter.c
@@ -1668,6 +1668,20 @@ enum gsp_phys_rmcall_buf {
 #define GSP_PHYS_RMCALL_TIMEOUT_MS	2000u
 #define GSP_PHYS_RMCALL_POLL_MS		5u
 /*
+ * SESSION 148 perf (termbin review, verified in-tree): every RPC reply wait
+ * polled with msleep(5). With several quanta per round trip and ~8
+ * serialized PDE_UPDATE forwards per forwarded GR launch, the 5 ms quantum
+ * dominated per-launch latency (~95% of the ~189 ms host service time per
+ * launch). Wait with sub-millisecond quanta instead: the reply is observed
+ * within one quantum, cutting each round trip to ~1 ms. POLL_MS remains for
+ * the poll accounting prints.
+ */
+#define GSP_PHYS_RMCALL_POLL_US		150u
+static inline void gsp_phys_rmcall_wait_quantum(void)
+{
+	usleep_range(GSP_PHYS_RMCALL_POLL_US, GSP_PHYS_RMCALL_POLL_US + 200u);
+}
+/*
  * GR launch release poll window. A CE copy completes in single-digit ms, but
  * a GR launch can force the engine's first context switch for the channel;
  * the FECS ctxsw path is measured in fractions of a second, so the window is
@@ -15371,7 +15385,7 @@ static int gsp_phys_rmcall_gr_sem_push_locked(void __iomem *bar0)
 			gsp_phys_status_drain(NULL);
 			return -ETIMEDOUT;
 		}
-		msleep(GSP_PHYS_RMCALL_POLL_MS);
+		gsp_phys_rmcall_wait_quantum();
 	}
 
 	gpget = get_unaligned_le32((u8 *)userd + gsp_phys_rmcall_userd_ctl_off() + GSP_PHYS_RMCALL_USERD_GPGET_OFF);
@@ -15471,7 +15485,7 @@ static void gsp_phys_rmcall_ctx_image_probe(void __iomem *bar0)
 					       offs[k], poll);
 					break;
 				}
-				msleep(GSP_PHYS_RMCALL_POLL_MS);
+				gsp_phys_rmcall_wait_quantum();
 			}
 			if (poll != GSP_PHYS_RMCALL_SEM_PAYLOAD)
 				break;
@@ -15572,7 +15586,7 @@ static int gsp_phys_rmcall_ce_copy_va(void __iomem *bar0, u64 src_va,
 				*sem_out = poll;
 			return -ETIMEDOUT;
 		}
-		msleep(GSP_PHYS_RMCALL_POLL_MS);
+		gsp_phys_rmcall_wait_quantum();
 	}
 }
 
@@ -15755,7 +15769,7 @@ int gsp_phys_backend_ce_copy_submit(u64 src_va, u64 dst_va, u64 sem_va,
 					gsp_phys_work_timed_out);
 			return -ETIMEDOUT;
 		}
-		msleep(GSP_PHYS_RMCALL_POLL_MS);
+		gsp_phys_rmcall_wait_quantum();
 	}
 
 	/*
@@ -16274,7 +16288,7 @@ static int gsp_phys_guest_ce_copy_common(u64 src_hpa, u32 src_off, u64 dst_hpa,
 			ret = -ETIMEDOUT;
 			goto out;
 		}
-		msleep(GSP_PHYS_RMCALL_POLL_MS);
+		gsp_phys_rmcall_wait_quantum();
 	}
 
 	/*
@@ -21235,7 +21249,7 @@ gr_page_unmapped:
 			ret = -ETIMEDOUT;
 			goto out;
 		}
-		msleep(GSP_PHYS_RMCALL_POLL_MS);
+		gsp_phys_rmcall_wait_quantum();
 	}
 
 	gsp_phys_gr_ok++;
@@ -21640,7 +21654,7 @@ gr_page_unmapped:
 						}
 						if (time_after_eq(jiffies, dl))
 							break;
-						msleep(GSP_PHYS_RMCALL_POLL_MS);
+						gsp_phys_rmcall_wait_quantum();
 					}
 					pr_info("vgsp-gr: outcome retry %u: fresh ack %s (qmd_rel=0x%08x want=0x%08x ch_rel=0x%08x after %u ms)\n",
 						nw_attempts,
@@ -22693,7 +22707,7 @@ static int gsp_phys_rmcall_stage4(void __iomem *bar0)
 			gsp_phys_status_drain(NULL);
 			return -ETIMEDOUT;
 		}
-		msleep(GSP_PHYS_RMCALL_POLL_MS);
+		gsp_phys_rmcall_wait_quantum();
 	}
 
 	if (memcmp(gsp_phys_chunk_page_va(src, 0),