From 042b8953823190623452c0539d1b6807450aa67a Mon Sep 17 00:00:00 2001 From: Arthur Hanson Rasmusson Date: Mon, 28 Sep 2026 15:20:04 -0400 Subject: sema: add walk_probe - trace the page-table walk for a VA New module parameter walk_probe runs the recorded-va-space walks and the discovered-directory walk directly (pin/lat/pair map bypassed) with per-level tracing, and prints the result of each. This separates 'the page tables are not walkable' from 'the VA->PA pair map already answers' when a translation is missing. Baseline on a live boot: root PDB entries are zero (L0 e=0 idx=0) so the writes UVM issues into the level pages have no parent entry yet. --- kernel/main.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'kernel/main.c') diff --git a/kernel/main.c b/kernel/main.c index 4f7f9ee..dcfdeed 100644 --- a/kernel/main.c +++ b/kernel/main.c @@ -2247,6 +2247,27 @@ static const struct kernel_param_ops nv_vgpu_sema_probe_ops = { module_param_cb(sema_probe, &nv_vgpu_sema_probe_ops, NULL, 0200); MODULE_PARM_DESC(sema_probe, "Dump sema-service map + slot values for a GPU VA"); +/* + * Debug: run the page-table walks for a GPU VA with per-level tracing, + * bypassing the pin/lat/pair map (see gsp_sema_service_walk_probe): + * echo 0x20400f000 > .../parameters/walk_probe + */ +static int nv_vgpu_walk_probe_set(const char *val, const struct kernel_param *kp) +{ + u64 va = 0; + + if (kstrtoull(val, 0, &va)) + return -EINVAL; + return gsp_sema_service_walk_probe(va); +} + +static const struct kernel_param_ops nv_vgpu_walk_probe_ops = { + .set = nv_vgpu_walk_probe_set, +}; + +module_param_cb(walk_probe, &nv_vgpu_walk_probe_ops, NULL, 0200); +MODULE_PARM_DESC(walk_probe, "Trace the page-table walks for a GPU VA (hex)"); + /* * Debug: dump the semaphore service's channel table (GPFIFO/USERD state and * the two NvNotification slots each channel exposes): -- cgit v1.2.3