vgsp-rm: PROMOTE_CTX reply must keep bInitialize set (ISSUE-0001)

kgrobjPromoteContext_IMPL marks each ctx buffer initialized when the
REPLY's promoteEntry[i].bInitialize is set:

    if (!params.promoteEntry[i].bInitialize) continue;
    kgrctxMarkCtxBufferInitialized(...);

The flag is the server's initialized-ACK, so the correct emulation reply is
a verbatim echo (the physical backend owns residency; the control answers
SUCCESS). 7ce387f3 cleared the flag believing the check inverted - that
skipped the mark and left the RM re-promoting the same buffers forever.
Restore echo semantics with the source-cited comment.

1 files changed, 41 insertions, 22 deletions

diff --git a/kernel/gsp_rm_emulation.c b/kernel/gsp_rm_emulation.c
index 2d66912..2ad1ba7 100644
--- a/kernel/gsp_rm_emulation.c
+++ b/kernel/gsp_rm_emulation.c
@@ -3092,40 +3092,59 @@ static void gsp_rm_handle_rm_control(struct gsp_emu_context *ctx,
 		    req.paramsSize + GSP_RM_CTRL_HDR_SIZE <=
 				GSPRM_MAX_SINGLE_ELEM_DATA) {
 			u8 *rp = reply + GSP_RM_CTRL_HDR_SIZE;
-			u32 cleared = 0;
+			u32 init_entries = 0, k;
 
-			memcpy(rp, pp, req.paramsSize);
 			/*
-			 * The caller (kgrobjPromoteContext_IMPL) marks each ctx
-			 * buffer initialized ONLY when the REPLY's bInitialize is
-			 * clear:
-			 *   if (!params.promoteEntry[i].bInitialize)
-			 *           continue;
-			 *   kgrctxMarkCtxBufferInitialized(...);
-			 * Echoing the request back keeps bInitialize set forever,
-			 * so the RM re-promotes the same context on every pass and
-			 * never submits the channel's first work (the client's
-			 * CUDA init then spins with an empty GR ring). Clear the
-			 * flag on the reply to acknowledge the (host-side)
-			 * initialization.
+			 * PROMOTE_CTX is an in/out control: the client allocates
+			 * one NV2080_CTRL_GPU_PROMOTE_CTX_PARAMS, fills the
+			 * entries that still need work (bInitialize=1 for a PA
+			 * initialization; the prepare helpers also emit VA
+			 * promotion entries), sends it, and reads the SAME
+			 * buffer back after the call. The reply decides whether
+			 * the client marks the ctx buffer initialized and stops
+			 * re-promoting it (kernel_graphics_object.c,
+			 * kgrobjPromoteContext_IMPL):
+			 *
+			 *   status = pRmApi->Control(..., &params, ...);
+			 *   if (status == NV_OK) {
+			 *       for (i = 0; i < entryCount; ++i) {
+			 *           if (!params.promoteEntry[i].bInitialize)
+			 *               continue;
+			 *           kgrctxMarkCtxBufferInitialized(...,
+			 *               params.promoteEntry[i].bufferId);
+			 *       }
+			 *   }
+			 *
+			 * The flag is therefore the server's "context buffer is
+			 * initialized" acknowledgement: an entry the client
+			 * asked to initialize must come back with bInitialize
+			 * STILL SET, or the client skips the mark, re-prepares
+			 * the same buffer on every pass and the context never
+			 * becomes usable. The physical backend owns the actual
+			 * residency and the emulation answers SUCCESS, so the
+			 * correct reply is a verbatim echo - the request's
+			 * flags already carry the values the client checks.
+			 * (fa9296af briefly cleared the flag believing the
+			 * check was inverted; that made the client re-promote
+			 * forever. This is the corrected semantics.)
 			 */
+			memcpy(rp, pp, req.paramsSize);
 			if (req.paramsSize >= 48) {
-				u32 ec = 0, k;
+				u32 ec = 0;
 
 				memcpy(&ec, pp + 40, 4);
 				for (k = 0; k < ec &&
 				     48u + (k + 1u) * 32u <= req.paramsSize;
 				     k++) {
-					if (rp[48 + k * 32 + 30]) {
-						rp[48 + k * 32 + 30] = 0;
-						cleared++;
-					}
+					if (rp[48 + k * 32 + 30])
+						init_entries++;
 				}
 			}
-			if (cleared)
+			if (init_entries)
 				nv_vgpu_info(ctx->vgpu,
-					     "vgsp-rm: PROMOTE_CTX reply acked init on %u entr%s (bInitialize cleared)",
-					     cleared, cleared == 1 ? "y" : "ies");
+					     "vgsp-rm: PROMOTE_CTX reply confirms %u initialize entr%s (bInitialize kept; client will mark ctx buffers initialized)",
+					     init_entries,
+					     init_entries == 1 ? "y" : "ies");
 		}
 		break;
 	}