sema-svc: sema_vidmem_dump param to inspect emulated vidmem (CE data-path audit)

1 files changed, 30 insertions, 0 deletions

diff --git a/kernel/main.c b/kernel/main.c
index 454f3b9..52156dc 100644
--- a/kernel/main.c
+++ b/kernel/main.c
@@ -2540,6 +2540,36 @@ module_param_cb(sema_counter, &nv_vgpu_sema_counter_ops, NULL, 0200);
 MODULE_PARM_DESC(sema_counter, "Register channel GPU completion counter (h_object,pa)");
 
 /*
+ * Debug: dump a range of the emulated vidmem (BAR1 shadow) into the kernel
+ * log, to verify where a decoded CE copy actually landed:
+ *   echo 0x227000,256 > .../parameters/sema_vidmem_dump
+ */
+static int nv_vgpu_sema_vidmem_dump_set(const char *val,
+					const struct kernel_param *kp)
+{
+	char buf[64];
+	char *comma;
+	u64 addr = 0, len = 0;
+
+	strscpy(buf, val, sizeof(buf));
+	comma = strchr(buf, ',');
+	if (!comma)
+		return -EINVAL;
+	*comma = '\0';
+	if (kstrtoull(buf, 0, &addr) || kstrtoull(comma + 1, 0, &len))
+		return -EINVAL;
+
+	return gsp_sema_service_dump_vidmem(addr, len);
+}
+
+static const struct kernel_param_ops nv_vgpu_sema_vidmem_dump_ops = {
+	.set = nv_vgpu_sema_vidmem_dump_set,
+};
+
+module_param_cb(sema_vidmem_dump, &nv_vgpu_sema_vidmem_dump_ops, NULL, 0200);
+MODULE_PARM_DESC(sema_vidmem_dump, "Dump emulated vidmem (addr,len) to the kernel log");
+
+/*
  * Debug: find page-table entries pointing at a physical address, in guest RAM
  * and emulated vidmem:
  *   echo 0x12442b000 > .../parameters/scan_pt