Re: [PATCH v7 12/13] ACPI / init: Invoke early ACPI initialization earlier

[Dou Liyang]

Hi Rafael, Zheng,

At 07/31/2017 06:50 PM, Dou Liyang wrote:
> Hi,
>
> At 07/14/2017 01:52 PM, Dou Liyang wrote:
> > Linux uses acpi_early_init() to put the ACPI table management into
> > the late stage from the early stage where the mapped ACPI tables is
> > temporary and should be unmapped.
> >
> > But, now initializing interrupt delivery mode should map and parse the
> > DMAR table earlier in the early stage. This causes an ACPI error when
> > Linux reallocates the ACPI root tables. Because Linux doesn't unmapped
> > the DMAR table after using in the early stage.
> >
> > Invoke acpi_early_init() earlier before late_time_init(), Keep the DMAR
> > be mapped and parsed in late stage like before.
> >
> > Reported-by: Xiaolong Ye <xiaolong.ye@xxxxxxxxx>
> > Signed-off-by: Dou Liyang <douly.fnst@xxxxxxxxxxxxxx>
> > Cc: linux-acpi@xxxxxxxxxxxxxxx
> > Cc: Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>
> > Cc: Zheng, Lv <lv.zheng@xxxxxxxxx>
> > Cc: Julian Wollrath <jwollrath@xxxxxx>
> > ---
> > Test in my own PC(Lenovo M4340).
> > Ask help for doing regression testing for the bug said in commit
> > c4e1acbb35e4
> > ("ACPI / init: Invoke early ACPI initialization later").
>
> Now, I can prove this patch doesn't result in the bug[1] which made the
> fast TSC calibration using PIT failed in a Thinkpad x121e (AMD E-450
> APU).
>
> The true reason of the bug is enabling ACPI subsystem earlier than
> using PIT, not the SCI setup. invoking acpi_enable_subsystem() later
> could fix this bug as Julian tested and said[2].
>
> And, I found that Commit b064a8fa77df (" ACPI / init: Switch over
> platform to the ACPI mode later") split the ACPI early initialization
> code into acpi_early_init() and acpi_subsystem_init(). executing
> acpi_enable_subsystem() at the original early ACPI initialization spot.
>
> The sequence of them shows below:
>
>  start_kernel
> +---------------+
> |
> +--> .......
> |
> |    late_time_init()
> +--> +-------+
> |
> +--> .......
> |
> |    acpi_early_init()
> +--> +-------+
> |
> +--> .......
> |
> |   acpi_subsystem_init()
> +-> +--------+
>
> We make sure the acpi_subsystem_init() is called later than
> late_time_init(), the bug will be avoided.
>
> This patch changes the sequence of late_time_init() and
> acpi_early_init(), doesn't effect acpi_subsystem_init().
>
> So, this patch is OK.
>
> Btw, Thanks very much for Borislav Petkov, he will have access to
> Thinkpad x121e from Mid-August and will test this series.

Almost one month passed, Borislav have tested this series in Thinkpad
x121e and I also have tested in my box and QEmu again. It is OK.

BTW,
1) I found your commit b064a8fa77df (" ACPI / init: Switch over
platform to the ACPI mode later") split the ACPI early initialization
code into acpi_early_init() and acpi_subsystem_init(). Actually enabling
the ACPI subsystem is in acpi_subsystem_init().

2) As we discussed earlier, invoking acpi_put_table() is not good for
this situation.

So I do this patch, Is that goot to you? Any comments will be welcome.

If it is OK, As the patches need to be re-based, and I also found
several spelling mistake, I will send a new version next week.

Thanks,
	dou.

> [1] https://lkml.org/lkml/2014/3/10/123
> [2] https://lkml.org/lkml/2014/3/12/311
>
>
> Thanks
>     dou.
>
> >  init/main.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/init/main.c b/init/main.c
> > index df58a41..7a09467 100644
> > --- a/init/main.c
> > +++ b/init/main.c
> > @@ -654,12 +654,12 @@ asmlinkage __visible void __init start_kernel(void)
> >      kmemleak_init();
> >      setup_per_cpu_pageset();
> >      numa_policy_init();
> > +    acpi_early_init();
> >      if (late_time_init)
> >          late_time_init();
> >      calibrate_delay();
> >      pidmap_init();
> >      anon_vma_init();
> > -    acpi_early_init();
> >  #ifdef CONFIG_X86
> >      if (efi_enabled(EFI_RUNTIME_SERVICES))
> >          efi_enter_virtual_mode();