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

[Dou Liyang]

Hi, Zheng

At 07/28/2017 09:53 AM, Zheng, Lv wrote:
[...]
> > > Dmar hardware support interrupt remapping and io remapping separately. But
> > > intel_iommu_init() is called later than intel_prepare_irq_remapping().
> > > So what if make dmar_table_init() a reentrant function? You can just
> > > have a try, but maybe not a good idea, the dmar table will be parsed
> > > twice.
> >
> > Yes, It is precisely one reason that I gave up invoking
> > acpi_put_table().
>
> Parsing a table twice is not a problem on x86.
> If you check the code, there are many examples.
> It's actually required if you want to use a table both in early stage and late stage.

I am sorry I don't explain clearly.

Yeah, in current kernel, The DMAR table has been parsed twice as well.
one is in detect_intel_iommu(), the other is in dmar_table_init().

Here we focus on the reentrant dmar_table_init(), this func contains
many callback for parsing different DMAR type structures, such as DRHD,
RMRR.

acpi_put_table() can release the mapped DMAR address, but we should
clear the remapping structure types manually. and I think parsing these
DMAR type structures again may have an influence on interrupt remapping.


Thanks,

	dou.

> Thanks
>
> > Thanks,
> >
> > 	dou.
> >
> > > > Thanks,
> > > >
> > > > 	dou.
> > > > > Thanks
> > > > > Lv
> > > > >
> > > > > > From: Dou Liyang [mailto:douly.fnst@xxxxxxxxxxxxxx]
> > > > > > Sent: Friday, July 14, 2017 1:53 PM
> > > > > > To: x86@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> > > > > > Cc: tglx@xxxxxxxxxxxxx; mingo@xxxxxxxxxx; hpa@xxxxxxxxx; ebiederm@xxxxxxxxxxxx; bhe@xxxxxxxxxx;
> > > > > > peterz@xxxxxxxxxxxxx; izumi.taku@xxxxxxxxxxxxxx; tokunaga.keiich@xxxxxxxxxxxxxx; Dou Liyang
> > > > > > <douly.fnst@xxxxxxxxxxxxxx>; linux-acpi@xxxxxxxxxxxxxxx; Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>;
> > Zheng,
> > > > > > Lv <lv.zheng@xxxxxxxxx>; Julian Wollrath <jwollrath@xxxxxx>
> > > > > > Subject: [PATCH v7 12/13] ACPI / init: Invoke early ACPI initialization earlier
> > > > > >
> > > > > > 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").
> > > > > >
> > > > > >  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();
> > > > > > --
> > > > > > 2.5.5