Re: [PATCH v3 08/16] irqchip/gic: Configure SGIs as standard interrupts

Marek Szyprowski
2020-09-15T06:48:12Z

Hi Marc,

On 14.09.2020 17:09, Marc Zyngier wrote:
> On 2020-09-14 14:26, Marek Szyprowski wrote:
>> On 14.09.2020 15:13, Marc Zyngier wrote:
>>> On 2020-09-14 14:06, Marek Szyprowski wrote:
>>>> On 01.09.2020 16:43, Marc Zyngier wrote:
>>>>> Change the way we deal with GIC SGIs by turning them into proper
>>>>> IRQs, and calling into the arch code to register the interrupt range
>>>>> instead of a callback.
>>>>>
>>>>> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
>>>>> Signed-off-by: Marc Zyngier <maz@kernel.org>
>>>> This patch landed in linux next-20200914 as commit ac063232d4b0
>>>> ("irqchip/gic: Configure SGIs as standard interrupts"). Sadly it
>>>> breaks
>>>> booting of all Samsung Exynos 4210/4412 based boards (dual/quad ARM
>>>> Cortex A9 based). Here are the last lines from the bootlog:
>>>>
>>>> [    0.106322] CPU: Testing write buffer coherency: ok
>>>> [    0.109895] CPU0: Spectre v2: using BPIALL workaround
>>>> [    0.116057] CPU0: thread -1, cpu 0, socket 9, mpidr 80000900
>>>> [    0.123885] Setting up static identity map for 0x40100000 -
>>>> 0x40100060
>>>> [    0.130191] rcu: Hierarchical SRCU implementation.
>>>> [    0.137195] soc soc0: Exynos: CPU[EXYNOS4210] PRO_ID[0x43210211]
>>>> REV[0x11] Detected
>>>> [    0.145129] smp: Bringing up secondary CPUs ...
>>>> [    0.156279] CPU1: thread -1, cpu 1, socket 9, mpidr 80000901
>>>> [    0.156291] CPU1: Spectre v2: using BPIALL workaround
>>>> [    2.716379] random: fast init done
>>>
>>> Thanks for the report. Is this the funky non-banked GIC?
>>
>> Both Exynos 4210 and 4412 use non-zero cpu-offset in GIC node in
>> device-tree: arch/arm/boot/dts/exynos{4210,4412}.dtsi, so I assume that
>> the GIC registers are not banked.
>
> Annoyingly, it seems to work correctly in QEMU:
>
> root@unassigned-hostname:~# cat /proc/interrupts
>            CPU0       CPU1
>  40:          0          0     GIC-0  89 Level     mct_comp_irq
>  41:      16144          0     GIC-0  74 Level     mct_tick0
>  42:          0      15205     GIC-0  80 Level     mct_tick1
>  43:          0          0  COMBINER  18 Edge      arm-pmu
>  44:          0          0  COMBINER  26 Edge      arm-pmu
>  46:       2270          0     GIC-0 107 Level     mmc0
>  48:        878          0     GIC-0  84 Level     13800000.serial
>  52:          0          0     GIC-0  90 Level     13860000.i2c
>  54:          0          0     GIC-0  67 Level     12680000.pdma
>  55:          0          0     GIC-0  68 Level     12690000.pdma
>  56:          0          0     GIC-0  66 Level     12850000.mdma
>  59:          0          0  COMBINER  45 Edge      13620000.sysmmu
>  60:          0          0  COMBINER  46 Edge      13630000.sysmmu
>  61:          0          0  COMBINER  44 Edge      12e20000.sysmmu
>  62:          0          0  COMBINER  34 Edge      11a20000.sysmmu
>  63:          0          0  COMBINER  35 Edge      11a30000.sysmmu
>  64:          0          0  COMBINER  36 Edge      11a40000.sysmmu
>  65:          0          0  COMBINER  37 Edge      11a50000.sysmmu
>  66:          0          0  COMBINER  38 Edge      11a60000.sysmmu
>  67:          0          0  COMBINER  40 Edge      12a30000.sysmmu
>  68:          0          0  COMBINER  42 Edge      11e20000.sysmmu
>  74:          0          0     GIC-0  79 Level 11400000.pinctrl
>  75:          0          0     GIC-0  78 Level 11000000.pinctrl
>  77:          0          0  COMBINER  39 Edge      12a20000.sysmmu
>  78:          0          0  COMBINER  43 Edge      12220000.sysmmu
> IPI0:          0          1  CPU wakeup interrupts
> IPI1:          0          0  Timer broadcast interrupts
> IPI2:         32         63  Rescheduling interrupts
> IPI3:       3925       5381  Function call interrupts
> IPI4:          0          0  CPU stop interrupts
> IPI5:       4375       3778  IRQ work interrupts
> IPI6:          0          0  completion interrupts
> Err:          0
>
> Do you happen to know whether the QEMU emulation is trustworthy?

I didn't play much with Exynos emulation on QEMU. All I know is that
this patch simply doesn't work on the real hw.

If there is anything to check or test, let me know. I will try to help
as much as possible.

Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland