On 2020-02-07 at 00:00:13 +0530, Anshuman Gupta wrote:
> On 2020-02-06 at 23:06:57 +0530, Ramalingam C wrote:
> > On 2020-02-06 at 22:39:28 +0530, Anshuman Gupta wrote:
> > > On 2020-02-06 at 22:30:27 +0530, Ramalingam C wrote:
> > > > On 2020-02-06 at 20:34:41 +0530, Anshuman Gupta wrote:
> > > > > HDCP Repeater initializes seq_num_V to 0 at the beginning of
> > > > > hdcp Session i.e. after AKE_init received.
> > > > >
> > > > > HDCP 2.2 Comp specs 1B-06 test verifies that whether DUT
> > > > > considers failures of authentication if the repeater provides a
> > > > > non-zero value in seq_num_V in the first,
> > > > > RepeaterAuth_Send_ReceiverID_List message after first AKE_Init.
> > > > > Fixing this broken test.
> > > > Instead of "Fixing the broken test" could we say, we mandate the first
> > > > seq_num_v to be zero? in fact i would keep this as commit subject also.
> > > > >
> > > > > Cc: Ramalingam C <ramalingam.c@xxxxxxxxx>
> > > > > Signed-off-by: Anshuman Gupta <anshuman.gupta@xxxxxxxxx>
> > > > > ---
> > > > > drivers/gpu/drm/i915/display/intel_display_types.h | 3 +++
> > > > > drivers/gpu/drm/i915/display/intel_hdcp.c | 13 +++++++++++++
> > > > > 2 files changed, 16 insertions(+)
> > > > >
> > > > > diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> > > > > index 7ae0bc8b80d1..2ae540e986ba 100644
> > > > > --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> > > > > +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> > > > > @@ -360,6 +360,9 @@ struct intel_hdcp {
> > > > > /* HDCP2.2 Encryption status */
> > > > > bool hdcp2_encrypted;
> > > > >
> > > > > + /* Flag indicate if it is a first ReceiverID_List msg after AKE_Init */
> > > > > + bool first_recvid_msg;
> > > > This extra flag is not needed, see below comment
> > > > > +
> > > > > /*
> > > > > * Content Stream Type defined by content owner. TYPE0(0x0) content can
> > > > > * flow in the link protected by HDCP2.2 or HDCP1.4, where as TYPE1(0x1)
> > > > > diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c
> > > > > index 4d1a33d13105..3e24a6df503a 100644
> > > > > --- a/drivers/gpu/drm/i915/display/intel_hdcp.c
> > > > > +++ b/drivers/gpu/drm/i915/display/intel_hdcp.c
> > > > > @@ -1251,6 +1251,8 @@ static int hdcp2_authentication_key_exchange(struct intel_connector *connector)
> > > > > size_t size;
> > > > > int ret;
> > > > >
> > > > > + hdcp->first_recvid_msg = true;
> > > > > +
> > > > > /* Init for seq_num */
> > > > > hdcp->seq_num_v = 0;
> > > > > hdcp->seq_num_m = 0;
> > > > > @@ -1462,6 +1464,16 @@ int hdcp2_authenticate_repeater_topology(struct intel_connector *connector)
> > > > > seq_num_v =
> > > > > drm_hdcp_be24_to_cpu((const u8 *)msgs.recvid_list.seq_num_v);
> > > > >
> > > > > + /*
> > > > > + * HDCP 2.2 Spec HDMI PAGE 19, DP PAGE 20
> > > > > + * HDCP 2.2 Comp 1B-06 test requires to disable encryption if there is
> > > > > + * non zero seq_num_V from recevier.
> > > > IMHO In commit message this kind of reasoning make sense, but here this is
> > > > not needed. As every line in the file will be as per the spec so we dont
> > > > need to call them out.
> > > > > + */
> > > > > + if (hdcp->first_recvid_msg && seq_num_v) {
> > > > if (!hdcp->seq_num_v && seq_num_v) {
> > > >
> > > > IMO This is all we need it.
> > > I had tried this as my first solution, eventually this fill the link integrity check, see below.
> > > >
> > > > -Ram
> > > > > + drm_dbg_kms(&dev_priv->drm, "Non zero Seq_num_v at beginning of HDCP Session\n");
> > > > > + return -EINVAL;
> > > > > + }
> > > > > +
> > > > > if (seq_num_v < hdcp->seq_num_v) {
> > > > > /* Roll over of the seq_num_v from repeater. Reauthenticate. */
> > > > > DRM_DEBUG_KMS("Seq_num_v roll over.\n");
> > > > > @@ -1484,6 +1496,7 @@ int hdcp2_authenticate_repeater_topology(struct intel_connector *connector)
> > > > > return ret;
> > > > >
> > > > > hdcp->seq_num_v = seq_num_v;
> > > seq_num_v will be zero for first session, which left hdcp->seq_num_v to zero and that will
> > > fail the link intergrity check as at during link intergrity check seq_num_v will be non-zero,
> > > this happens during 1B-09, when repeater topolgy changes due to Roll over of seq_num_v.
> >
> > topology update should increment the seq_num_v which will make it > than
> > hdcp->seq_num_v. How roll over happens? And at every AKE start we init
> > hdcp->seq_num_v to 0.
> >
> > So please elaborate the failure scenario.
> Please refer to HDCP 2.2 spec page page 44 Step 1-B-09
> STEP 1B-09-01
> -> TE sets seq_num_V to 0xFFFFFFh
Is it possible to randomly set seq_num_v to 0xFFFFFFh after 0? thought
it is getting incremented by 1 for every topology change.
> -> TE simulate disconnect of active downstream device by decrementing DEVICE_COUNT
> *As I understand above will assert the READY bit that will detect as topology change and will make a call
> to hdcp2_authenticate_repeater_topology() and there it will fail for
> if (!hdcp->seq_num_v && seq_num_v) conidiation, and test will fail here itself.
possible if the TE change the seq_num_v from 0 to ffffffh directly. Need
to check whether that is ok to do?
> -> DUT sends RepeaterAuth_Send_Ack message
> STEP 1B-09-02
> -> TE will set seq_num_V to 0x000 to indicate Roll Over.
>
> Please correct me if i am wrong here.
if not the hdcp->seq_num_v, you can use hdcp->value which will be
ENABLED for repeated topology change or you can use
hdcp->hdcp2_encrypted which will be true in above roll over case.
Thanks,
Ram.
>
> Thanks ,
> Anshuman Gupta.
>
> >
> > Ram.
> > > Thanks ,
> > > Anshuman Gupta.
> > >
> > > > > + hdcp->first_recvid_msg = false;
> > > > > ret = shim->write_2_2_msg(intel_dig_port, &msgs.rep_ack,
> > > > > sizeof(msgs.rep_ack));
> > > > > if (ret < 0)
> > > > > --
> > > > > 2.24.0
> > > > >
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