[PATCH v9 12/18] drm/dp_mst: Add branch bandwidth validation to MST atomic check
Mikita Lipski
mlipski at amd.com
Fri Jan 17 15:26:54 UTC 2020
On 1/17/20 10:09 AM, Sean Paul wrote:
> On Fri, Dec 13, 2019 at 3:09 PM <mikita.lipski at amd.com> wrote:
>>
>> From: Mikita Lipski <mikita.lipski at amd.com>
>>
>
> Hi Mikita,
> Unfortunately this patch causes a crash on my i915 device when I
> unplug my MST hub. The panic is below.
Hi Sean,
I thought this issue was fixed by Wayne Lin in
https://patchwork.freedesktop.org/patch/346736/?series=71388&rev=1
but now I checked it seems it never got pushed. I will resend Wayne's
patch once again.
Thanks
Mikita
>
> [ 38.514014] BUG: kernel NULL pointer dereference, address: 0000000000000030
> [ 38.521801] #PF: supervisor read access in kernel mode
> [ 38.527556] #PF: error_code(0x0000) - not-present page
> [ 38.533299] PGD 0 P4D 0
> [ 38.536127] Oops: 0000 [#1] PREEMPT SMP PTI
> [ 38.540798] CPU: 1 PID: 1324 Comm: DrmThread Not tainted
> 5.5.0-rc6-02273-g9bb4096398e7 #36
> [ 38.550040] Hardware name: Google Fizz/Fizz, BIOS
> Google_Fizz.10139.39.0 01/04/2018
> [ 38.558606] RIP: 0010:drm_dp_mst_atomic_check_bw_limit+0x11/0x102
> [ 38.565418] Code: 05 ff cb bf 19 48 f7 f6 c3 0f 1f 44 00 00 55 b8
> 0b 80 ff 0f 48 89 e5 5d c3 55 48 89 e5 41 57 41 56 41 55 41 54 4c 8d
> 77 30 53 <48> 8b 47 30 49 89 fd 49 89 f7 45 31 e4 48 8d 58 e8 48 8d 53
> 18 4c
> [ 38.586422] RSP: 0018:ffffc9000139f9d8 EFLAGS: 00010282
> [ 38.592264] RAX: 0000000000000000 RBX: ffff888272aeac88 RCX: ffff888236f529e0
> [ 38.600242] RDX: ffff888272aeac88 RSI: ffff888236f529e0 RDI: 0000000000000000
> [ 38.608220] RBP: ffffc9000139fa00 R08: 0000000000000031 R09: 000000000000000e
> [ 38.616198] R10: ffff888236f529e8 R11: ffff8882621f3440 R12: 0000000000000000
> [ 38.624176] R13: ffff888236f529d0 R14: 0000000000000030 R15: ffff888236f529e0
> [ 38.632153] FS: 00007cd9229ce700(0000) GS:ffff888276c80000(0000)
> knlGS:0000000000000000
> [ 38.641193] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 38.647616] CR2: 0000000000000030 CR3: 00000002618e8004 CR4: 00000000003606e0
> [ 38.655593] Call Trace:
> [ 38.658329] drm_dp_mst_atomic_check+0x152/0x16d
> [ 38.663484] intel_atomic_check+0xcfe/0x1e6f
> [ 38.668259] ? trace_hardirqs_on+0x28/0x3d
> [ 38.672835] ? intel_pipe_config_compare+0x1b38/0x1b38
> [ 38.678580] drm_atomic_check_only+0x5ab/0x70f
> [ 38.683547] ? drm_atomic_set_crtc_for_connector+0xf5/0x102
> [ 38.689778] ? drm_atomic_helper_shutdown+0xb6/0xb6
> [ 38.695221] drm_atomic_commit+0x18/0x53
> [ 38.699604] drm_atomic_helper_set_config+0x5a/0x70
> [ 38.705057] drm_mode_setcrtc+0x2ab/0x833
> [ 38.709537] ? rcu_read_unlock+0x57/0x57
> [ 38.713920] ? drm_mode_getcrtc+0x173/0x173
> [ 38.718594] drm_ioctl+0x2e5/0x424
> [ 38.722392] ? drm_mode_getcrtc+0x173/0x173
> [ 38.727069] vfs_ioctl+0x21/0x2f
> [ 38.730675] do_vfs_ioctl+0x5fb/0x61e
> [ 38.734766] ksys_ioctl+0x55/0x75
> [ 38.738469] __x64_sys_ioctl+0x1a/0x1e
> [ 38.742659] do_syscall_64+0x5c/0x6d
> [ 38.746653] entry_SYSCALL_64_after_hwframe+0x49/0xbe
> [ 38.752298] RIP: 0033:0x7cd92552d497
> [ 38.756291] Code: 8a 66 90 48 8b 05 d1 d9 2b 00 64 c7 00 26 00 00
> 00 48 c7 c0 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 b8 10 00 00
> 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d a1 d9 2b 00 f7 d8 64 89
> 01 48
> [ 38.777296] RSP: 002b:00007cd9229cd698 EFLAGS: 00000246 ORIG_RAX:
> 0000000000000010
> [ 38.785762] RAX: ffffffffffffffda RBX: 000020323373da80 RCX: 00007cd92552d497
> [ 38.793740] RDX: 00007cd9229cd6d0 RSI: 00000000c06864a2 RDI: 000000000000001c
> [ 38.801717] RBP: 00007cd9229cd6c0 R08: 0000000000000000 R09: 0000000000000000
> [ 38.809693] R10: 0000000000000000 R11: 0000000000000246 R12: 000000000000001c
> [ 38.817670] R13: 0000000000000000 R14: 00007cd9229cd6d0 R15: 00000000c06864a2
> [ 38.825642] Modules linked in: xt_nat cdc_ether r8152 bridge stp
> llc usbhid btusb btrtl btbcm btintel bluetooth asix usbnet
> ecdh_generic ecc mii snd_soc_hdac_hdmi snd_soc_dmic xhci_pci xhci_hcd
> snd_soc_skl snd_soc_sst_ipc snd_soc_sst_dsp snd_hda_ext_core
> snd_intel_dspcfg snd_hda_core usbcore usb_common acpi_als kfifo_buf
> industrialio xt_MASQUERADE iptable_nat nf_nat xt_mark fuse
> ip6table_filter iwlmvm mac80211 r8169 realtek iwlwifi lzo_rle
> lzo_compress zram cfg80211
> [ 38.871839] CR2: 0000000000000030
> [ 38.875542] ---[ end trace 6bb39ec52e30c7cb ]---
> [ 38.886142] RIP: 0010:drm_dp_mst_atomic_check_bw_limit+0x11/0x102
> [ 38.892957] Code: 05 ff cb bf 19 48 f7 f6 c3 0f 1f 44 00 00 55 b8
> 0b 80 ff 0f 48 89 e5 5d c3 55 48 89 e5 41 57 41 56 41 55 41 54 4c 8d
> 77 30 53 <48> 8b 47 30 49 89 fd 49 89 f7 45 31 e4 48 8d 58 e8 48 8d 53
> 18 4c
> [ 38.913964] RSP: 0018:ffffc9000139f9d8 EFLAGS: 00010282
> [ 38.919804] RAX: 0000000000000000 RBX: ffff888272aeac88 RCX: ffff888236f529e0
> [ 38.927784] RDX: ffff888272aeac88 RSI: ffff888236f529e0 RDI: 0000000000000000
> [ 38.935765] RBP: ffffc9000139fa00 R08: 0000000000000031 R09: 000000000000000e
> [ 38.943733] R10: ffff888236f529e8 R11: ffff8882621f3440 R12: 0000000000000000
> [ 38.951712] R13: ffff888236f529d0 R14: 0000000000000030 R15: ffff888236f529e0
> [ 38.959692] FS: 00007cd9229ce700(0000) GS:ffff888276c80000(0000)
> knlGS:0000000000000000
> [ 38.968730] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 38.975144] CR2: 0000000000000030 CR3: 00000002618e8004 CR4: 00000000003606e0
> [ 38.983121] Kernel panic - not syncing: Fatal exception
> [ 38.988967] Kernel Offset: disabled
> [ 38.998280] ---[ end Kernel panic - not syncing: Fatal exception ]---
>
>
>
>
>
>
>> [why]
>> Adding PBN attribute to drm_dp_vcpi_allocation structure to
>> keep track of how much bandwidth each Port requires.
>> Adding drm_dp_mst_atomic_check_bw_limit to verify that
>> state's bandwidth needs doesn't exceed available bandwidth.
>> The funtion is called in drm_dp_mst_atomic_check after
>> drm_dp_mst_atomic_check_topology_state to fully verify that
>> the proposed topology is supported.
>>
>> v2: Fixing some typos and indentations
>>
>> Reviewed-by: Lyude Paul <lyude at redhat.com>
>> Signed-off-by: Mikita Lipski <mikita.lipski at amd.com>
>> ---
>> drivers/gpu/drm/drm_dp_mst_topology.c | 66 ++++++++++++++++++++++++++-
>> include/drm/drm_dp_mst_helper.h | 1 +
>> 2 files changed, 65 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
>> index 7cd505e771ff..f8b72ac79c66 100644
>> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
>> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
>> @@ -4052,7 +4052,7 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
>> {
>> struct drm_dp_mst_topology_state *topology_state;
>> struct drm_dp_vcpi_allocation *pos, *vcpi = NULL;
>> - int prev_slots, req_slots;
>> + int prev_slots, prev_bw, req_slots;
>>
>> topology_state = drm_atomic_get_mst_topology_state(state, mgr);
>> if (IS_ERR(topology_state))
>> @@ -4063,6 +4063,7 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
>> if (pos->port == port) {
>> vcpi = pos;
>> prev_slots = vcpi->vcpi;
>> + prev_bw = vcpi->pbn;
>>
>> /*
>> * This should never happen, unless the driver tries
>> @@ -4078,8 +4079,10 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
>> break;
>> }
>> }
>> - if (!vcpi)
>> + if (!vcpi) {
>> prev_slots = 0;
>> + prev_bw = 0;
>> + }
>>
>> if (pbn_div <= 0)
>> pbn_div = mgr->pbn_div;
>> @@ -4089,6 +4092,9 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
>> DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] [MST PORT:%p] VCPI %d -> %d\n",
>> port->connector->base.id, port->connector->name,
>> port, prev_slots, req_slots);
>> + DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] [MST PORT:%p] PBN %d -> %d\n",
>> + port->connector->base.id, port->connector->name,
>> + port, prev_bw, pbn);
>>
>> /* Add the new allocation to the state */
>> if (!vcpi) {
>> @@ -4101,6 +4107,7 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
>> list_add(&vcpi->next, &topology_state->vcpis);
>> }
>> vcpi->vcpi = req_slots;
>> + vcpi->pbn = pbn;
>>
>> return req_slots;
>> }
>> @@ -4677,6 +4684,58 @@ static void drm_dp_mst_destroy_state(struct drm_private_obj *obj,
>> kfree(mst_state);
>> }
>>
>> +static bool drm_dp_mst_port_downstream_of_branch(struct drm_dp_mst_port *port,
>> + struct drm_dp_mst_branch *branch)
>> +{
>> + while (port->parent) {
>> + if (port->parent == branch)
>> + return true;
>> +
>> + if (port->parent->port_parent)
>> + port = port->parent->port_parent;
>> + else
>> + break;
>> + }
>> + return false;
>> +}
>> +
>> +static inline
>> +int drm_dp_mst_atomic_check_bw_limit(struct drm_dp_mst_branch *branch,
>> + struct drm_dp_mst_topology_state *mst_state)
>> +{
>> + struct drm_dp_mst_port *port;
>> + struct drm_dp_vcpi_allocation *vcpi;
>> + int pbn_limit = 0, pbn_used = 0;
>> +
>> + list_for_each_entry(port, &branch->ports, next) {
>> + if (port->mstb)
>> + if (drm_dp_mst_atomic_check_bw_limit(port->mstb, mst_state))
>> + return -EINVAL;
>> +
>> + if (port->available_pbn > 0)
>> + pbn_limit = port->available_pbn;
>> + }
>> + DRM_DEBUG_ATOMIC("[MST BRANCH:%p] branch has %d PBN available\n",
>> + branch, pbn_limit);
>> +
>> + list_for_each_entry(vcpi, &mst_state->vcpis, next) {
>> + if (!vcpi->pbn)
>> + continue;
>> +
>> + if (drm_dp_mst_port_downstream_of_branch(vcpi->port, branch))
>> + pbn_used += vcpi->pbn;
>> + }
>> + DRM_DEBUG_ATOMIC("[MST BRANCH:%p] branch used %d PBN\n",
>> + branch, pbn_used);
>> +
>> + if (pbn_used > pbn_limit) {
>> + DRM_DEBUG_ATOMIC("[MST BRANCH:%p] No available bandwidth\n",
>> + branch);
>> + return -EINVAL;
>> + }
>> + return 0;
>> +}
>> +
>> static inline int
>> drm_dp_mst_atomic_check_topology_state(struct drm_dp_mst_topology_mgr *mgr,
>> struct drm_dp_mst_topology_state *mst_state)
>> @@ -4808,6 +4867,9 @@ int drm_dp_mst_atomic_check(struct drm_atomic_state *state)
>> ret = drm_dp_mst_atomic_check_topology_state(mgr, mst_state);
>> if (ret)
>> break;
>> + ret = drm_dp_mst_atomic_check_bw_limit(mgr->mst_primary, mst_state);
>> + if (ret)
>> + break;
>> }
>>
>> return ret;
>> diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
>> index 830c94b7f45d..2919d9776af3 100644
>> --- a/include/drm/drm_dp_mst_helper.h
>> +++ b/include/drm/drm_dp_mst_helper.h
>> @@ -502,6 +502,7 @@ struct drm_dp_payload {
>> struct drm_dp_vcpi_allocation {
>> struct drm_dp_mst_port *port;
>> int vcpi;
>> + int pbn;
>> bool dsc_enabled;
>> struct list_head next;
>> };
>> --
>> 2.17.1
>>
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel at lists.freedesktop.org
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--
Thanks,
Mikita Lipski
Software Engineer 2, AMD
mikita.lipski at amd.com
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