Re: [PULL 31/35] hw/intc/allwinner-a10-pic: Don't use set_bit()/clear_bit()

[Guenter Roeck]

Hi,

On Tue, May 02, 2023 at 01:14:55PM +0100, Peter Maydell wrote:
> The Allwinner PIC model uses set_bit() and clear_bit() to update the
> values in its irq_pending[] array when an interrupt arrives.  However
> it is using these functions wrongly: they work on an array of type
> 'long', and it is passing an array of type 'uint32_t'.  Because the
> code manually figures out the right array element, this works on
> little-endian hosts and on 32-bit big-endian hosts, where bits 0..31
> in a 'long' are in the same place as they are in a 'uint32_t'.
> However it breaks on 64-bit big-endian hosts.
> 
> Remove the use of set_bit() and clear_bit() in favour of using
> deposit32() on the array element.  This fixes a bug where on
> big-endian 64-bit hosts the guest kernel would hang early on in
> bootup.
> 
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> Reviewed-by: Thomas Huth <thuth@redhat.com>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> Message-id: 20230424152833.1334136-1-peter.maydell@linaro.org

In v8.0.2, the cubieboard emulation running Linux crashes during reboot
with a hung task error. Tested with mainline Linux (v6.4-rc4-78-g929ed21dfdb6)
and with v5.15.114. Host is AMD Ryzen 5900X.

Requesting system reboot
[   61.927460] INFO: task kworker/0:1:13 blocked for more than 30 seconds.
[   61.927896]       Not tainted 5.15.115-rc2-00038-g31e35d9f1b8d #1
[   61.928144] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this 
message.
[   61.928419] task:kworker/0:1     state:D stack:    0 pid:   13 ppid:     2 
flags:0x00000000
[   61.928972] Workqueue: events_freezable mmc_rescan
[   61.929739] [<c13734f0>] (__schedule) from [<c1373c98>] (schedule+0x80/0x15c)
[   61.930041] [<c1373c98>] (schedule) from [<c137ad64>] 
(schedule_timeout+0xd4/0x12c)
[   61.930270] [<c137ad64>] (schedule_timeout) from [<c137477c>] 
(do_wait_for_common+0xa0/0x154)
[   61.930523] [<c137477c>] (do_wait_for_common) from [<c1374870>] 
(wait_for_completion+0x40/0x4c)
[   61.930764] [<c1374870>] (wait_for_completion) from [<c1044cd0>] 
(mmc_wait_for_req_done+0x6c/0x90)
[   61.931012] [<c1044cd0>] (mmc_wait_for_req_done) from [<c1044e34>] 
(mmc_wait_for_cmd+0x70/0xa8)
[   61.931252] [<c1044e34>] (mmc_wait_for_cmd) from [<c10512a0>] 
(sdio_reset+0x58/0x124)
[   61.931478] [<c10512a0>] (sdio_reset) from [<c1046328>] 
(mmc_rescan+0x294/0x30c)
[   61.931692] [<c1046328>] (mmc_rescan) from [<c036be10>] 
(process_one_work+0x28c/0x720)
[   61.931924] [<c036be10>] (process_one_work) from [<c036c308>] 
(worker_thread+0x64/0x53c)
[   61.932153] [<c036c308>] (worker_thread) from [<c03753e0>] 
(kthread+0x15c/0x180)
[   61.932365] [<c03753e0>] (kthread) from [<c030015c>] 
(ret_from_fork+0x14/0x38)
[   61.932628] Exception stack(0xc31ddfb0 to 0xc31ddff8)

This was not seen with v8.0.0. Bisect points to this patch. Reverting it
fixes the problem.

Bisect log is attached.

Guenter

---
# bad: [f7f686b61cf7ee142c9264d2e04ac2c6a96d37f8] Update version for 8.0.2 
release
# good: [c1eb2ddf0f8075faddc5f7c3d39feae3e8e9d6b4] Update version for v8.0.0 
release
git bisect start 'v8.0.2' 'v8.0.0'
# bad: [21b54a683d14c0c6f9af35536d9059c60b7449ca] s390x/pv: Fix spurious 
warning with asynchronous teardown
git bisect bad 21b54a683d14c0c6f9af35536d9059c60b7449ca
# bad: [4dc5df865c482c6e8894964c7f300fa556c3b78e] softfloat: Fix the incorrect 
computation in float32_exp2
git bisect bad 4dc5df865c482c6e8894964c7f300fa556c3b78e
# good: [f0c5a780292bd405bbce818b63757313cafcf262] target/arm: Initialize debug 
capabilities only once
git bisect good f0c5a780292bd405bbce818b63757313cafcf262
# bad: [af08c70ef5204fedb2b974fbecaf65e1b6cc0a2f] hw/intc/allwinner-a10-pic: 
Don't use set_bit()/clear_bit()
git bisect bad af08c70ef5204fedb2b974fbecaf65e1b6cc0a2f
# good: [168f193c5be54fc9a6d725dbb9974c0d2815792a] hw/arm/boot: Make 
write_bootloader() public as arm_write_bootloader()
git bisect good 168f193c5be54fc9a6d725dbb9974c0d2815792a
# good: [975f12aa528d6cab5cc41efebaf05d7eb7296d94] hw/arm/raspi: Use 
arm_write_bootloader() to write boot code
git bisect good 975f12aa528d6cab5cc41efebaf05d7eb7296d94
# first bad commit: [af08c70ef5204fedb2b974fbecaf65e1b6cc0a2f] 
hw/intc/allwinner-a10-pic: Don't use set_bit()/clear_bit()