boot regression on ppc64 with linux 6.2

[Andrea Righi]

I'm triggering the following bug when booting my qemu powerpc VM:

event-sources: Unable to request interrupt 23 for /event-sources/hot-plug-events
WARNING: CPU: 0 PID: 1 at arch/powerpc/platforms/pseries/event_sources.c:26 request_event_sources_irqs+0xbc/0xf0
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W          6.2.2-kc #1
Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1200 0xf000005 of:SLOF,HEAD pSeries
NIP:  c000000002022eec LR: c000000002022ee8 CTR: 0000000000000000
REGS: c000000003483910 TRAP: 0700   Tainted: G        W           (6.2.2-kc)
MSR:  8000000002029033 <SF,VEC,EE,ME,IR,DR,RI,LE>  CR: 24483200  XER: 00000000
CFAR: c000000000180838 IRQMASK: 0 
GPR00: c000000002022ee8 c000000003483bb0 c000000001a5ce00 0000000000000050 
GPR04: c000000002437d78 c000000002437e28 0000000000000001 0000000000000001 
GPR08: c000000002437d00 0000000000000001 0000000000000000 0000000044483200 
GPR12: 0000000000000000 c000000002720000 c000000000012758 0000000000000000 
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
GPR24: 0000000000000000 c0000000020033fc cccccccccccccccd c0000000000e07f0 
GPR28: c000000000db0520 0000000000000000 c0000000fff92ac0 0000000000000017 
NIP [c000000002022eec] request_event_sources_irqs+0xbc/0xf0
LR [c000000002022ee8] request_event_sources_irqs+0xb8/0xf0
Call Trace:
[c000000003483bb0] [c000000002022ee8] request_event_sources_irqs+0xb8/0xf0 (unreliable)
[c000000003483c40] [c000000002022fa0] __machine_initcall_pseries_init_ras_hotplug_IRQ+0x80/0xb0
[c000000003483c70] [c0000000000121b8] do_one_initcall+0x98/0x300
[c000000003483d50] [c000000002004b28] kernel_init_freeable+0x2ec/0x370
[c000000003483df0] [c000000000012780] kernel_init+0x30/0x190
[c000000003483e50] [c00000000000cf5c] ret_from_kernel_thread+0x5c/0x64
--- interrupt: 0 at 0x0

I did a bisect it and it seems that the offending commit is:
baa49d81a94b ("powerpc/pseries: hvcall stack frame overhead")

Reverting that and also dfecd06bc552 ("powerpc: remove
STACK_FRAME_OVERHEAD"), because we need to re-introduce
STACK_FRAME_OVERHEAD, seems to fix everything.

-Andrea