vgsp: V6 client-owned ctx-buffer VA commit path (srvctx)

Source-confirmed: with the SKIP_CTXBUFFER_ALLOC channel flag the server does
not allocate MAIN, does not map/book it, and its internal init/promote
helpers return early for KMD virtual contexts. The client therefore owns the
buffer. When no server MAIN is reported on a V6 channel, map the prepared
client MAIN at the ladder ctx VA (sysmem PTEs), send GPU_INITIALIZE_CTX to
install the memdesc, then the UVM-shape VA-only promote; with no server
pre-booking the vaListSetManaged gate should pass and the per-buffer commit
program the engine context pointer. V5 keeps the historical PA-only
fallback. Build clean; not hardware-tested (GPU wedged).

1 files changed, 33 insertions, 2 deletions

diff --git a/kernel/gsp_phys_booter.c b/kernel/gsp_phys_booter.c
index ebe873b..8a27edf 100644
--- a/kernel/gsp_phys_booter.c
+++ b/kernel/gsp_phys_booter.c
@@ -1356,6 +1356,10 @@ static struct gsp_phys_boot_stage {
 	 * The engine context pointer needs a VA; a PA-only entry books none.
 	 */
 	bool rmcall_srv_ctxva;
+	/* true when the VA path commits the CLIENT buffer (V6 KMD virtual
+	 * context: the server neither allocates nor books the ctx buffer), so
+	 * INITIALIZE_CTX must run first to install the memdesc. */
+	bool rmcall_srv_ctxva_client;
 	/* Server-reported PATCH buffer (bufferType 2), mapped at VA_GR_PATCH
 	 * on the server-VA path and promoted VA-only with MAIN. */
 	bool rmcall_srv_patch_valid;
@@ -2032,6 +2036,7 @@ static void gsp_phys_rmcall_reset(void)
 	boot_stage.rmcall_srv_main_size = 0;
 	boot_stage.rmcall_srv_main_aperture = 0;
 	boot_stage.rmcall_srv_ctxva = false;
+	boot_stage.rmcall_srv_ctxva_client = false;
 	boot_stage.rmcall_srv_patch_valid = false;
 	boot_stage.rmcall_srv_patch_pa = 0;
 	boot_stage.rmcall_srv_patch_size = 0;
@@ -9140,6 +9145,28 @@ static int gsp_phys_rmcall_srv_ctx_commit(void __iomem *bar0)
 		pa_attr = GSP_PHYS_RMCALL_GR_CTX_PHYS_ATTR;
 		pr_warn("vgsp-boot: rm-call: server MAIN ctx buffer was not reported; committing the CLIENT MAIN buffer pa=0x%llx size=0x%llx mapped (VA 0x%llx, PDE installed) instead\n",
 			main_pa, main_size, GSP_PHYS_RMCALL_VA_GR_CTX);
+		/*
+		 * V6 (SKIP_CTXBUFFER_ALLOC, KMD virtual context): the server
+		 * neither allocates MAIN nor books the engine-ctx vaList
+		 * (kgrctxAllocCtxBuffers / kgrctxMapCtxBuffers skip on this
+		 * flag), so the client owns the buffer. Map the prepared client
+		 * buffer at the ctx VA and commit it with the UVM-shape VA-only
+		 * promote; because no engine-ctx memdesc exists yet,
+		 * INITIALIZE_CTX runs first to install one from the client
+		 * PA/size. The V5 fallback keeps the historical PA-only promote.
+		 */
+		if (boot_stage.rmcall_channel_variant ==
+				gsp_phys_rmcall_channel_variant_skipctx.id &&
+		    boot_stage.rmcall_ctx_prepared &&
+		    boot_stage.rmcall_ctx_pt_pages > 0) {
+			boot_stage.rmcall_ctx_va = GSP_PHYS_RMCALL_VA_GR_CTX;
+			boot_stage.rmcall_srv_ctxva = true;
+			boot_stage.rmcall_srv_ctxva_client = true;
+			gsp_phys_rmcall_pdb_build();
+			pr_info("vgsp-boot: rm-call: client MAIN mapped at VA 0x%llx (sysmem PTEs, %u pages); the KMD VA-only promote will commit it\n",
+				boot_stage.rmcall_ctx_va,
+				boot_stage.rmcall_ctx_pages);
+		}
 	}
 
 	/*
@@ -9150,9 +9177,13 @@ static int gsp_phys_rmcall_srv_ctx_commit(void __iomem *bar0)
 	 * already-initialized gate). Send only the UVM-shape VA-only promote
 	 * entries (bInitialize=0, bNonmapped=0, gpuVirtAddr only), which take
 	 * the per-buffer VA commit branch and program the engine context
-	 * pointer. Otherwise: INITIALIZE_CTX + PATCH/MAIN PA-only.
+	 * pointer. Exception: the V6 client-buffer VA path has no engine
+	 * memdesc yet, so INITIALIZE_CTX installs one from the client PA/size
+	 * before the VA promote. Otherwise: INITIALIZE_CTX + PATCH/MAIN
+	 * PA-only.
 	 */
-	if (!boot_stage.rmcall_srv_ctxva) {
+	if (!boot_stage.rmcall_srv_ctxva ||
+	    boot_stage.rmcall_srv_ctxva_client) {
 		ic = kvzalloc(sizeof(*ic), GFP_KERNEL);
 		if (!ic)
 			return -ENOMEM;