From 412e85b605315fd129a849599cf4a5a7959573a8 Mon Sep 17 00:00:00 2001 From: Lyude Paul Date: Thu, 1 Aug 2019 18:02:15 -0400 Subject: drm/nouveau: Only release VCPI slots on mode changes Looks like a regression got introduced into nv50_mstc_atomic_check() that somehow didn't get found until now. If userspace changes crtc_state->active to false but leaves the CRTC enabled, we end up calling drm_dp_atomic_find_vcpi_slots() using the PBN calculated in asyh->dp.pbn. However, if the display is inactive we end up calculating a PBN of 0, which inadvertently causes us to have an allocation of 0. >From there, if userspace then disables the CRTC afterwards we end up accidentally attempting to free the VCPI twice: WARNING: CPU: 0 PID: 1484 at drivers/gpu/drm/drm_dp_mst_topology.c:3336 drm_dp_atomic_release_vcpi_slots+0x87/0xb0 [drm_kms_helper] RIP: 0010:drm_dp_atomic_release_vcpi_slots+0x87/0xb0 [drm_kms_helper] Call Trace: drm_atomic_helper_check_modeset+0x3f3/0xa60 [drm_kms_helper] ? drm_atomic_check_only+0x43/0x780 [drm] drm_atomic_helper_check+0x15/0x90 [drm_kms_helper] nv50_disp_atomic_check+0x83/0x1d0 [nouveau] drm_atomic_check_only+0x54d/0x780 [drm] ? drm_atomic_set_crtc_for_connector+0xec/0x100 [drm] drm_atomic_commit+0x13/0x50 [drm] drm_atomic_helper_set_config+0x81/0x90 [drm_kms_helper] drm_mode_setcrtc+0x194/0x6a0 [drm] ? vprintk_emit+0x16a/0x230 ? drm_ioctl+0x163/0x390 [drm] ? drm_mode_getcrtc+0x180/0x180 [drm] drm_ioctl_kernel+0xaa/0xf0 [drm] drm_ioctl+0x208/0x390 [drm] ? drm_mode_getcrtc+0x180/0x180 [drm] nouveau_drm_ioctl+0x63/0xb0 [nouveau] do_vfs_ioctl+0x405/0x660 ? recalc_sigpending+0x17/0x50 ? _copy_from_user+0x37/0x60 ksys_ioctl+0x5e/0x90 ? exit_to_usermode_loop+0x92/0xe0 __x64_sys_ioctl+0x16/0x20 do_syscall_64+0x59/0x190 entry_SYSCALL_64_after_hwframe+0x44/0xa9 WARNING: CPU: 0 PID: 1484 at drivers/gpu/drm/drm_dp_mst_topology.c:3336 drm_dp_atomic_release_vcpi_slots+0x87/0xb0 [drm_kms_helper] ---[ end trace 4c395c0c51b1f88d ]--- [drm:drm_dp_atomic_release_vcpi_slots [drm_kms_helper]] *ERROR* no VCPI for [MST PORT:00000000e288eb7d] found in mst state 000000008e642070 So, fix this by doing what we probably should have done from the start: only call drm_dp_atomic_find_vcpi_slots() when crtc_state->mode_changed is set, so that VCPI allocations remain for as long as the CRTC is enabled. Signed-off-by: Lyude Paul Fixes: 232c9eec417a ("drm/nouveau: Use atomic VCPI helpers for MST") Cc: Lyude Paul Cc: Ben Skeggs Cc: Daniel Vetter Cc: David Airlie Cc: Jerry Zuo Cc: Harry Wentland Cc: Juston Li Cc: Karol Herbst Cc: Laurent Pinchart Cc: Ilia Mirkin Cc: # v5.1+ Acked-by: Ben Skeggs Signed-off-by: Dave Airlie Link: https://patchwork.freedesktop.org/patch/msgid/20190801220216.15323-1-lyude@redhat.com --- drivers/gpu/drm/nouveau/dispnv50/disp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/gpu/drm/nouveau/dispnv50/disp.c') diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c index 8497768f1b41..126703816794 100644 --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c @@ -780,7 +780,7 @@ nv50_msto_atomic_check(struct drm_encoder *encoder, drm_dp_calc_pbn_mode(crtc_state->adjusted_mode.clock, connector->display_info.bpc * 3); - if (drm_atomic_crtc_needs_modeset(crtc_state)) { + if (crtc_state->mode_changed) { slots = drm_dp_atomic_find_vcpi_slots(state, &mstm->mgr, mstc->port, asyh->dp.pbn); -- cgit v1.2.3 From db1231ddc04682f60d56ff42447f13099c6c4a4c Mon Sep 17 00:00:00 2001 From: Lyude Paul Date: Thu, 8 Aug 2019 20:53:05 -0400 Subject: drm/nouveau: Only recalculate PBN/VCPI on mode/connector changes MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit I -thought- I had fixed this entirely, but it looks like that I didn't test this thoroughly enough as we apparently still make one big mistake with nv50_msto_atomic_check() - we don't handle the following scenario: * CRTC #1 has n VCPI allocated to it, is attached to connector DP-4 which is attached to encoder #1. enabled=y active=n * CRTC #1 is changed from DP-4 to DP-5, causing: * DP-4 crtc=#1→NULL (VCPI n→0) * DP-5 crtc=NULL→#1 * CRTC #1 steals encoder #1 back from DP-4 and gives it to DP-5 * CRTC #1 maintains the same mode as before, just with a different connector * mode_changed=n connectors_changed=y (we _SHOULD_ do VCPI 0→n here, but don't) Once the above scenario is repeated once, we'll attempt freeing VCPI from the connector that we didn't allocate due to the connectors changing, but the mode staying the same. Sigh. Since nv50_msto_atomic_check() has broken a few times now, let's rethink things a bit to be more careful: limit both VCPI/PBN allocations to mode_changed || connectors_changed, since neither VCPI or PBN should ever need to change outside of routing and mode changes. Changes since v1: * Fix accidental reversal of clock and bpp arguments in drm_dp_calc_pbn_mode() - William Lewis Signed-off-by: Lyude Paul Reported-by: Bohdan Milar Tested-by: Bohdan Milar Fixes: 232c9eec417a ("drm/nouveau: Use atomic VCPI helpers for MST") References: 412e85b60531 ("drm/nouveau: Only release VCPI slots on mode changes") Cc: Lyude Paul Cc: Ben Skeggs Cc: Daniel Vetter Cc: David Airlie Cc: Jerry Zuo Cc: Harry Wentland Cc: Juston Li Cc: Laurent Pinchart Cc: Karol Herbst Cc: Ilia Mirkin Cc: # v5.1+ Acked-by: Ben Skeggs Signed-off-by: Dave Airlie Link: https://patchwork.freedesktop.org/patch/msgid/20190809005307.18391-1-lyude@redhat.com --- drivers/gpu/drm/nouveau/dispnv50/disp.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) (limited to 'drivers/gpu/drm/nouveau/dispnv50/disp.c') diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c index 126703816794..5c36c75232e6 100644 --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c @@ -771,16 +771,20 @@ nv50_msto_atomic_check(struct drm_encoder *encoder, struct nv50_head_atom *asyh = nv50_head_atom(crtc_state); int slots; - /* When restoring duplicated states, we need to make sure that the - * bw remains the same and avoid recalculating it, as the connector's - * bpc may have changed after the state was duplicated - */ - if (!state->duplicated) - asyh->dp.pbn = - drm_dp_calc_pbn_mode(crtc_state->adjusted_mode.clock, - connector->display_info.bpc * 3); + if (crtc_state->mode_changed || crtc_state->connectors_changed) { + /* + * When restoring duplicated states, we need to make sure that + * the bw remains the same and avoid recalculating it, as the + * connector's bpc may have changed after the state was + * duplicated + */ + if (!state->duplicated) { + const int bpp = connector->display_info.bpc * 3; + const int clock = crtc_state->adjusted_mode.clock; + + asyh->dp.pbn = drm_dp_calc_pbn_mode(clock, bpp); + } - if (crtc_state->mode_changed) { slots = drm_dp_atomic_find_vcpi_slots(state, &mstm->mgr, mstc->port, asyh->dp.pbn); -- cgit v1.2.3