[PATCH] irqchip/gic-v3-its: Reconfigure ITS from software state on resume

[Bjoern Doebel]

Hi all,

gentle ping on this one.

Since the original posting I've re-validated the fix against current
mainline:

  - It still applies cleanly to v7.2-rc1 (and to v7.1.0).

  - I reproduced the original failure on *stock* v7.2-rc1. On EC2
    Graviton instances, hibernation resume fails 100% of the time: the
    ITS comes back reset, MAPD/MAPTI are never replayed, and the ENA
    NIC silently loses its LPIs:

      ena 0000:00:05.0: ... didn't receive a MSI-X interrupt (cmd 3)
      ena 0000:00:05.0: Failed to create IO CQ. error: -62

    The instance then has no networking after resume.

  - With this patch applied, the same kernel survives hibernate/resume
    cleanly: 9/9 cycles with zero failures, across all three Graviton
    generations (Graviton 2/3/4, i.e. Neoverse N1/V1/V2), networking
    fully restored on every resume.

As described in the previous message, this is the fallout from 713335b6ee29
("irqchip/gic-v3-its: Implement .msi_teardown() callback"): device
teardown no longer happens across a suspend/resume that keeps the MSI
domain, so the ITS is never reprogrammed and drops interrupts after the
hardware has been reset.

Could you take a look when you get a chance?

Thanks,
Bjoern




Amazon Web Services Development Center Germany GmbH
Tamara-Danz-Str. 13
10243 Berlin
Geschaeftsfuehrung: Christof Hellmis, Andreas Stieger
Eingetragen am Amtsgericht Charlottenburg unter HRB 257764 B
Sitz: Berlin
Ust-ID: DE 365 538 597