From bde9352a0f84bdf0ef7bdfdc150f5f11a9200af3 Mon Sep 17 00:00:00 2001 From: Arthur Hanson Rasmusson Date: Mon, 28 Sep 2026 09:09:13 -0400 Subject: sem: run GR channels - accept CE methods on subchannel 0, discover GR rings - The CE semaphore/memset method groups also arrive on subchannel 0 (CUDA's push library binds the copy class on compute channels to carry the work-submission releases), so the stream decoder accepts both 0 and 4. - GR (compute) channel rings live in the same video-memory allocation as the CE rings, 0x3000 bytes per channel after them: ring (0x2000) at ce_end + 0x3000*rank, USERD at +0x2000. Discover and pin them once the CE ranks are known; verified against ring entry 0 (1 MB aligned push VA in the client window, sane length) and the USERD's put/get, so a layout change costs a failed pin, not a wrong one. Gated by sema_gr_rings (default on). - memprobe: require the sem-VA triple in the sem-object scanner (a bare qword in the window matches thousands of unrelated pointers once the ring/pushbuffer windows are part of the range). Live evidence: ring entries read through the guest's /proc/pid/mem decode to the GR channels' first pushes; pinning the ring (fb 0x140000+0x3000*rank), USERD (ring+0x2000) and first-push pages made all 20 GR channels execute their entry 0 for the first time (get=1 sub=1). --- kernel/main.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'kernel/main.c') diff --git a/kernel/main.c b/kernel/main.c index f23be27..4f7f9ee 100644 --- a/kernel/main.c +++ b/kernel/main.c @@ -2264,6 +2264,14 @@ static const struct kernel_param_ops nv_vgpu_chan_dump_ops = { module_param_cb(chan_dump, &nv_vgpu_chan_dump_ops, NULL, 0200); MODULE_PARM_DESC(chan_dump, "Dump the sema service channel table (any value)"); +/* + * GR ring discovery: pin the compute channels' rings/USERDs, which follow the + * CE rings in the channel video-memory allocation. Default on; set 0 to leave + * GR channels untranslated when debugging push-execution side effects. + */ +module_param_named(sema_gr_rings, gsp_sema_gr_rings, bool, 0644); +MODULE_PARM_DESC(sema_gr_rings, "Auto-discover+pin GR channel rings (default 1)"); + /* * Debug: inject a verified {GPU VA -> guest PA} translation into the * semaphore service (used when the client's mapping cannot be discovered -- cgit v1.2.3