Date:   Sun, 21 Aug 2022 19:06:30 +0300
From:   Igor Kononenko <i.kononenko@...ro.com>
To:     Corey Minyard <minyard@....org>, Joel Stanley <joel@....id.au>,
        "Andrew Jeffery" <andrew@...id.au>
CC:     <openipmi-developer@...ts.sourceforge.net>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-aspeed@...ts.ozlabs.org>, <linux-kernel@...r.kernel.org>,
        <openbmc@...ts.ozlabs.org>, Igor Kononenko <i.kononenko@...ro.com>
Subject: [PATCH 0/3] aspeed:lpc: Fix lpc-snoop probe exception

The bmc might be rebooted while the host is still reachable and the host
might send requests through configured lpc-kcs channels in same time.
That leads to raise lpc-snoop/lpc-kcs interrupts that haven't adjusted IRQ
handlers yet on next early kernel boot, because on the aspeed-chip reboot
might keep lpc-registers on a unclean state that is configured on the last
boot.

The described way might raise the next exception:
```
[    1.360110] irq 35: nobody cared (try booting with the "irqpoll" option)
[    1.360145] CPU: 0 PID: 1 Comm: swapper Not tainted 5.4.43-c109de3-24cc5b6 #1
[    1.360158] Hardware name: Generic DT based system
[    1.360168] Backtrace:
[    1.360228] [<80107f5c>] (dump_backtrace) from [<80108184>] (show_stack+0x20/0x24)
[    1.360250]  r7:00000023 r6:00000000 r5:00000000 r4:9d12d560
[    1.360283] [<80108164>] (show_stack) from [<8084ae54>] (dump_stack+0x20/0x28)
[    1.360316] [<8084ae34>] (dump_stack) from [<80156790>] (__report_bad_irq+0x40/0xc0)
[    1.360344] [<80156750>] (__report_bad_irq) from [<801566c0>] (note_interrupt+0x238/0x290)
[    1.360366]  r9:9d0ae000 r8:9d00c600 r7:00000023 r6:00000000 r5:00000000 r4:9d12d560
[    1.360408] [<80156488>] (note_interrupt) from [<80153594>] (handle_irq_event+0xb4/0xc4)
[    1.360429]  r10:00000000 r9:9d0ae000 r8:9d00c600 r7:00000001 r6:00000000 r5:00000000
[    1.360440]  r4:9d12d560 r3:00000000
[    1.360466] [<801534e0>] (handle_irq_event) from [<8015788c>] (handle_level_irq+0xac/0x180)
[    1.360480]  r5:80c7d35c r4:9d12d560
[    1.360503] [<801577e0>] (handle_level_irq) from [<80152a5c>] (__handle_domain_irq+0x6c/0xc8)
[    1.360519]  r5:80c7d35c r4:9d12d560
[    1.360545] [<801529f0>] (__handle_domain_irq) from [<801021cc>] (avic_handle_irq+0x68/0x70)
[    1.360568]  r9:9d0ae000 r8:9d12d608 r7:9d0afc84 r6:ffffffff r5:9d0afc50 r4:9d002380
[    1.360587] [<80102164>] (avic_handle_irq) from [<80101a6c>] (__irq_svc+0x6c/0x90)
[    1.360603] Exception stack(0x9d0afc50 to 0x9d0afc98)
[    1.360620] fc40:                                     00000000 00000100 00000000 00000000
[    1.360640] fc60: 9d12d560 98bbd0c0 00000000 00000023 9d12d608 60000053 00000000 9d0afcd4
[    1.360657] fc80: 9d0afc80 9d0afca0 801570ec 80154cdc 40000053 ffffffff
[    1.360670]  r5:40000053 r4:80154cdc
[    1.360693] [<801549e0>] (__setup_irq) from [<801555e4>] (request_threaded_irq+0xdc/0x15c)
[    1.360715]  r9:98bbb340 r8:00000023 r7:9d12d570 r6:9d12d560 r5:00000000 r4:98bbd0c0
[    1.360741] [<80155508>] (request_threaded_irq) from [<801589d8>] (devm_request_threaded_irq+0x70/0xc4)
[    1.360762]  r10:80a7353c r9:00000000 r8:98bbb340 r7:9d130e10 r6:00000023 r5:804f4a70
[    1.360774]  r4:98bbd020 r3:00000080
[    1.360800] [<80158968>] (devm_request_threaded_irq) from [<804f4ebc>] (aspeed_lpc_snoop_probe+0x100/0x2ac)
[    1.360821]  r10:00000000 r9:9d130e10 r8:98bbd040 r7:00000000 r6:9d130e00 r5:98bbb340
[    1.360830]  r4:00000000
[    1.360851] [<804f4dbc>] (aspeed_lpc_snoop_probe) from [<8056a5c4>] (platform_drv_probe+0x44/0x80)
[    1.360873]  r9:80c5ef90 r8:00000000 r7:80cc2938 r6:00000000 r5:80c5ef90 r4:9d130e10
[    1.360910] [<8056a580>] (platform_drv_probe) from [<80568420>] (really_probe+0x26c/0x498)
[    1.360924]  r5:80cc282c r4:9d130e10
[    1.360949] [<805681b4>] (really_probe) from [<80568c28>] (driver_probe_device+0x138/0x184)
[    1.360970]  r10:80b0050c r9:80adadb0 r8:00000007 r7:80c5ef90 r6:9d130e10 r5:00000000
[    1.360981]  r4:80c5ef90
[    1.361004] [<80568af0>] (driver_probe_device) from [<80568fe4>] (device_driver_attach+0xb8/0xc0)
[    1.361020]  r7:80c5ef90 r6:9d130e54 r5:00000000 r4:9d130e10
[    1.361046] [<80568f2c>] (device_driver_attach) from [<80569070>] (__driver_attach+0x84/0x16c)
[    1.361063]  r7:80c61128 r6:9d130e10 r5:00000001 r4:80c5ef90
[    1.361088] [<80568fec>] (__driver_attach) from [<80566068>] (bus_for_each_dev+0x84/0xcc)
[    1.361106]  r7:80c61128 r6:80568fec r5:80c5ef90 r4:00000000
[    1.361130] [<80565fe4>] (bus_for_each_dev) from [<80569180>] (driver_attach+0x28/0x30)
[    1.361147]  r6:00000000 r5:9d1a3d40 r4:80c5ef90
[    1.361169] [<80569158>] (driver_attach) from [<80566a08>] (bus_add_driver+0x114/0x200)
[    1.361195] [<805668f4>] (bus_add_driver) from [<80569814>] (driver_register+0x98/0x128)
[    1.361214]  r7:00000000 r6:80ca0ca0 r5:00000000 r4:80c5ef90
[    1.361241] [<8056977c>] (driver_register) from [<8056b528>] (__platform_driver_register+0x40/0x54)
[    1.361256]  r5:000000b8 r4:80b2575c
[    1.361294] [<8056b4e8>] (__platform_driver_register) from [<80b2577c>] (aspeed_lpc_snoop_driver_init+0x20/0x28)
[    1.361331] [<80b2575c>] (aspeed_lpc_snoop_driver_init) from [<80b01318>] (do_one_initcall+0x84/0x184)
[    1.361356] [<80b01294>] (do_one_initcall) from [<80b01540>] (kernel_init_freeable+0x128/0x1ec)
[    1.361375]  r7:80b3f858 r6:80ca0ca0 r5:000000b8 r4:80b61914
[    1.361412] [<80b01418>] (kernel_init_freeable) from [<80864060>] (kernel_init+0x18/0x11c)
[    1.361435]  r10:00000000 r9:00000000 r8:00000000 r7:00000000 r6:00000000 r5:80864048
[    1.361444]  r4:00000000
[    1.361470] [<80864048>] (kernel_init) from [<801010e8>] (ret_from_fork+0x14/0x2c)
[    1.361483] Exception stack(0x9d0affb0 to 0x9d0afff8)
[    1.361500] ffa0:                                     00000000 00000000 00000000 00000000
[    1.361518] ffc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[    1.361535] ffe0: 00000000 00000000 00000000 00000000 00000013 00000000
[    1.361547]  r5:80864048 r4:00000000
[    1.361555] handlers:
[    1.361592] [<(ptrval)>] aspeed_lpc_snoop_irq
[    1.361609] Disabling IRQ #35

```

Main caught of that state is the lpc-snoop driver found on the same
1e789080 address and have same IRQ#35 as for lpc-kcs, and lpc-snoop
registering earlier than lpc-kcs. So, on the lpc-snoop initialization
the lpc-snoop IRQ will be registried for IRQ#35, but it will
passthrough it for the LPC KCS handlers that is not registried yet.

Summary we got the `nobody cared` warning about more 100.000 unhandled
IRQ#35

Steps to reproduce:
* Turn-on BMC
* Turn-on HOST
* Run `watch 'ipmitool sensor'` on the host that is configured to pass
  requests via kcs-channel(3,4)
* Reboot BMC.
* On the next BMC boot kernel(BMC) dmesg have exception mentioned above.

The following patchset aims to fixup described issue.

Igor Kononenko (3):
  ipmi:kcs_bmc: Add cleanup regmap(interrupt-regs) on a shutdown.
  drivers/misc: (aspeed-lpc-snoop): Add regmap cleanup on a shutdown.
  drivers/misc: (aspeed-lpc-snoop): Fix platform_get_irq() error
    checking

 drivers/char/ipmi/kcs_bmc_aspeed.c    |  8 +++++
 drivers/soc/aspeed/aspeed-lpc-snoop.c | 46 ++++++++++++++++++++++++++-
 2 files changed, 53 insertions(+), 1 deletion(-)

-- 
2.25.1

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