From 38ba1e2d7d579c2467dfa10daca16cdbd6579089 Mon Sep 17 00:00:00 2001 From: Arthur Hanson Rasmusson Date: Tue, 27 Oct 2026 07:06:12 -0400 Subject: vgsp: channel-scoped VA resolution via the channel's own VAS (r835) Every RM client maps different objects at the same numeric VAs (all clients' windows sit at 0x1200xxxxx), so the global VA-keyed pin/lat/map layers conflate them across clients. Live walk_probe evidence (r834): the X server's ring VA 0x120090000 resolved through the GL client's page tables (vas h=0xcaf00005 -> a zero page) while the X client's own VAS (vas h=0x10005) holds the real page (pa=0x1294fa000). That conflation is what wedged the X server's readback wait and starved the RC watchdog's ring (its pushes decoded as empty). * Parse NV_CHANNEL_ALLOC_PARAMS.hVASpace (@28; layout confirmed by the struct's own known offsets) at channel registration and carry it on svc_channel. * svc_chanvas_lookup: resolve a VA through the serviced channel's own VAS page tables first (svc_cur_vas, refreshed per channel turn and in the decode path). The hook sits at the head of svc_lookup_trusted, so ring, push, release and notifier resolution all inherit it; a failed walk falls through to the old chain unchanged. Live r835: X's XShmGetImage readback, previously never completing, returned after its long wait and a frame reached the kvmfr BAR (first frame content still black and readback latency still ~87 s; the guest-side fbcopy_pub framebuffer reader tool is added for the direct-VRAM capture path, find/pub/test modes). --- kernel/gsp_rm_emulation.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'kernel/gsp_rm_emulation.c') diff --git a/kernel/gsp_rm_emulation.c b/kernel/gsp_rm_emulation.c index fc08b9d..7b7e230 100644 --- a/kernel/gsp_rm_emulation.c +++ b/kernel/gsp_rm_emulation.c @@ -3120,6 +3120,20 @@ static void gsp_rm_register_channel(struct gsp_emu_context *ctx, u32 h_object, */ if (desc.engine_type >= 1 && desc.engine_type <= 8) desc.engine_type = 0; + /* + * r835: the channel's own address space (NV_CHANNEL_ALLOC_PARAMS: + * hContextShare @24, hVASpace @28 - confirmed by this struct's own + * known offsets: engineType @128 = 32 + 8 handles + 8 subdevice + * handles + 8 u64 userd offsets). Two clients map different objects + * at overlapping VAs (everyone's RM window sits at 0x1200xxxxx), so + * the global VA-keyed translation maps conflate them: the X server's + * ring VA resolved through the GL client's page tables (walk-probe: + * vas h=0xcaf00005 answered 0x120090000 with a zero page) and its + * push stream decoded as empty, wedging X exactly like the RC + * watchdog's ring. The service resolves a channel's VAs through this + * VAS first. + */ + memcpy(&desc.h_vaspace, params + 28, 4); memcpy(&desc.cid, params + GSPRM_CHAN_CID, 4); memcpy(&desc.instance_pa, params + GSPRM_CHAN_INSTANCE_MEM, 8); memcpy(&desc.userd_pa, params + GSPRM_CHAN_USERD_MEM, 8); -- cgit v1.2.3