TF-A August 2026

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3 participants
4 discussions

SDEI: SDEI_EVENT_0 trigger dropped while PE masked — by design?

by wtliang785

Hi all, I'd like to ask whether the following behavior of SDEI_EVENT_0 is intended, and whether it's a known limitation of the SDEI + GIC SGI semantics. I've read the code carefully but want to confirm the intent before relying on or working around it. ## Setup - TF-A SDEI, event 0 is a "signalable" private event whose backing interrupt is a Secure SGI (on our platform, SGI 9). - include/services/sdei.h, SDEI_DEFINE_EVENT_0(_intr) -> SDEI_PRIVATE_EVENT(SDEI_EVENT_0, _intr, SDEI_MAPF_SIGNALABLE) - services/std_svc/sdei/sdei_main.c: asserts event 0 must be a Secure SGI and may only carry SIGNALABLE|PRIVATE. ## What I observe in code When the PE is SDEI-masked (client called SDEI_PE_MASK) and the SGI backing event 0 fires, the handler does *not* preserve the trigger: 1. The EL3 FIQ is taken and acked in bl31/ehf.c ehf_el3_interrupt_handler() via plat_ic_acknowledge_interrupt() (reads ICC_IAR — interrupt now Active, its Pending bit consumed). 2. It reaches sdei_intr_handler() (services/std_svc/sdei/sdei_intr_mgmt.c). At L463, state->pe_masked is true, so it calls handle_masked_trigger() and returns 0. 3. handle_masked_trigger() : /* Nothing to do for event 0 */ if (map->ev_num == SDEI_EVENT_0) return; i.e. for event 0 it does none of the "freeze for replay" steps that a normal private event takes : plat_ic_disable_interrupt(intr); plat_ic_set_interrupt_pending(intr); plat_ic_end_of_interrupt(intr_raw); state->pending_enables = true; So while the PE is masked, an event-0 trigger is acknowledged and then silently dropped, with nothing stored for replay on the next SDEI_PE_UNMASK. ## Why I think this happens (and want to confirm) The "freeze for replay" mechanism for normal private events relies on re-asserting Pending via plat_ic_set_interrupt_pending(), because the ack already consumed the Pending bit. But for an SGI this is not permitted — plat/common/plat_gicv3.c: asserts it out: void plat_ic_set_interrupt_pending(unsigned int id) { /* Disallow setting SGIs pending */ assert(id >= MIN_PPI_ID); gicv3_set_interrupt_pending(id, plat_my_core_pos()); } So event 0 (backed by an SGI) cannot have its Pending bit re-asserted in software, which is consistent with the "Nothing to do for event 0" early return. Combined with the level/merge semantics of GIC SGIs (a sender firing the same SGI N times is represented as a single Pending, not a count), this means a masked-PE client can at most learn "an event happened while masked", never how many or which — by design. ## My questions 1. Is dropping an event-0 trigger while the PE is masked the intended behaviour (a consequence of "event 0 is a signalable SGI, counting is not guaranteed"), rather than a bug? The "Nothing to do for event 0" comment reads as deliberate, but I'd like explicit confirmation. 2. Is the recommended mitigation simply to avoid firing event 0 while the PE is masked (buffer on the sender side, deliver after unmask), or to use a normal explicit event for anything requiring precise accounting? Or is there a platform hook intended for this case that I'm missing (e.g. plat_sdei_handle_masked_trigger — though that path is only taken for shared ANY-PE events , not event 0)? 3. Separately (not the focus of this question): on this masked path neither handle_masked_trigger() nor sdei_intr_handler() calls plat_ic_end_of_interrupt() for event 0, and neither the EHF top-level handler nor the runtime_exceptions.S dispatch macro performs a fallback EOI. So the acked SGI appears to be left Active with no EOI on this path. Is there a later EOI for this SGI that I've missed, or is that also expected here? I don't want to conflate this with the "drop" question above; I'm just flagging it. For reference, this is on an in-tree SDEI path; the platform only defines event 0 via SDEI_DEFINE_EVENT_0(PLAT_SDEI_SGI_PRIVATE) and does not modify handle_masked_trigger(). Thanks, Tianliang

1 day, 18 hours

Canceled event with note: TF-A Tech Forum @ Thu Aug 20, 2026 5pm - 6pm (GMT+2) (tf-a@lists.trustedfirmware.org)

by Olivier Deprez

This event has been canceled with a note: "Also cancelling Aug 20th instance as no topic and expected low attendance." TF-A Tech Forum Thursday Aug 20, 2026 ⋅ 5pm – 6pm Central European Time - Paris Location https://linaro-org.zoom.us/j/93557863987?pwd=56a1l8cBnetDTZ6eazHGaE1Ctk4W34… https://www.google.com/url?q=https%3A%2F%2Flinaro-org.zoom.us%2Fj%2F9355786… Trusted Firmware is inviting you to a scheduled Zoom meeting.Topic: TF-A Tech ForumTime: May 15, 2025 02:00 PM London Every 2 weeks on Thu, 78 occurrence(s)Please download and import the following iCalendar (.ics) files to your calendar system.Weekly: https://linaro-org.zoom.us/meeting/tJcocu6gqDgjEtOkyBhSQauR1sUyFwIcNKLa/ics… Zoom Meetinghttps://linaro-org.zoom.us/j/93557863987?pwd=56a1l8cBnetDTZ6eazHGaE1Ctk4W34.1Meeting ID: 935 5786 3987Passcode: 939141---One tap mobile+12532158782,,93557863987# US (Tacoma)+13017158592,,93557863987# US (Washington DC)---Dial by your location• +1 253 215 8782 US (Tacoma)• +1 301 715 8592 US (Washington DC)• +1 305 224 1968 US• +1 309 205 3325 US• +1 312 626 6799 US (Chicago)• +1 346 248 7799 US (Houston)• +1 360 209 5623 US• +1 386 347 5053 US• +1 507 473 4847 US• +1 564 217 2000 US• +1 646 558 8656 US (New York)• +1 646 931 3860 US• +1 669 444 9171 US• +1 669 900 9128 US (San Jose)• +1 689 278 1000 US• +1 719 359 4580 US• +1 253 205 0468 US• 833 548 0276 US Toll-free• 833 548 0282 US Toll-free• 833 928 4608 US Toll-free• 833 928 4609 US Toll-free• 833 928 4610 US Toll-free• 877 853 5247 US Toll-free• 888 788 0099 US Toll-freeMeeting ID: 935 5786 3987Find your local number: https://linaro-org.zoom.us/u/adoz9mILli Guests d82620130(a)gmail.com namyoon(a)google.com shaikadnanafrid(a)gmail.com tf-a(a)lists.trustedfirmware.org ~~//~~ Sent by Google Calendar: https://calendar.google.com/calendar/ You are receiving this email because you are an attendee on the event. Forwarding this invitation could allow any recipient to send a response to the organizer, be added to the guest list, invite others regardless of their own invitation status, or modify your RSVP. Learn more https://support.google.com/calendar/answer/37135#forwarding

2 weeks, 2 days

Canceled event with note: TF-A Tech Forum @ Thu Aug 6, 2026 5pm - 6pm (GMT+2) (tf-a@lists.trustedfirmware.org)

by Olivier Deprez

This event has been canceled with a note: "Hi Cancelling as topic on Aug 6th. Regards, Olivier. " TF-A Tech Forum Thursday Aug 6, 2026 ⋅ 5pm – 6pm Central European Time - Paris Location https://linaro-org.zoom.us/j/93557863987?pwd=56a1l8cBnetDTZ6eazHGaE1Ctk4W34… https://www.google.com/url?q=https%3A%2F%2Flinaro-org.zoom.us%2Fj%2F9355786… Trusted Firmware is inviting you to a scheduled Zoom meeting.Topic: TF-A Tech ForumTime: May 15, 2025 02:00 PM London Every 2 weeks on Thu, 78 occurrence(s)Please download and import the following iCalendar (.ics) files to your calendar system.Weekly: https://linaro-org.zoom.us/meeting/tJcocu6gqDgjEtOkyBhSQauR1sUyFwIcNKLa/ics… Zoom Meetinghttps://linaro-org.zoom.us/j/93557863987?pwd=56a1l8cBnetDTZ6eazHGaE1Ctk4W34.1Meeting ID: 935 5786 3987Passcode: 939141---One tap mobile+12532158782,,93557863987# US (Tacoma)+13017158592,,93557863987# US (Washington DC)---Dial by your location• +1 253 215 8782 US (Tacoma)• +1 301 715 8592 US (Washington DC)• +1 305 224 1968 US• +1 309 205 3325 US• +1 312 626 6799 US (Chicago)• +1 346 248 7799 US (Houston)• +1 360 209 5623 US• +1 386 347 5053 US• +1 507 473 4847 US• +1 564 217 2000 US• +1 646 558 8656 US (New York)• +1 646 931 3860 US• +1 669 444 9171 US• +1 669 900 9128 US (San Jose)• +1 689 278 1000 US• +1 719 359 4580 US• +1 253 205 0468 US• 833 548 0276 US Toll-free• 833 548 0282 US Toll-free• 833 928 4608 US Toll-free• 833 928 4609 US Toll-free• 833 928 4610 US Toll-free• 877 853 5247 US Toll-free• 888 788 0099 US Toll-freeMeeting ID: 935 5786 3987Find your local number: https://linaro-org.zoom.us/u/adoz9mILli Guests d82620130(a)gmail.com namyoon(a)google.com shaikadnanafrid(a)gmail.com tf-a(a)lists.trustedfirmware.org ~~//~~ Sent by Google Calendar: https://calendar.google.com/calendar/ You are receiving this email because you are an attendee on the event. Forwarding this invitation could allow any recipient to send a response to the organizer, be added to the guest list, invite others regardless of their own invitation status, or modify your RSVP. Learn more https://support.google.com/calendar/answer/37135#forwarding

2 weeks, 2 days

Lava Lab downtime tomorrow 06/06/2026

by Ben Copeland

Hello all, Please be aware that tomorrow, 06/06/2026, the Lava Lab will be down due to a UPS replacement. The time will be 13:00 to 17:00 (UTC+1). Regards Ben

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