Re: [PATCH] ACPI: x86: Call acpi_boot_table_init() after acpi_table_upgrade()

[David Hildenbrand]

On 13.04.21 19:53, Rafael J. Wysocki wrote:
> On Tue, Apr 13, 2021 at 7:43 PM David Hildenbrand <david@xxxxxxxxxx> wrote:
> > On 13.04.21 16:01, Rafael J. Wysocki wrote:
> > > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> > >
> > > Commit 1a1c130ab757 ("ACPI: tables: x86: Reserve memory occupied by
> > > ACPI tables") attempted to address an issue with reserving the memory
> > > occupied by ACPI tables, but it broke the initrd-based table override
> > > mechanism relied on by multiple users.
> > >
> > > To restore the initrd-based ACPI table override functionality, move
> > > the acpi_boot_table_init() invocation in setup_arch() on x86 after
> > > the acpi_table_upgrade() one.
> > >
> > > Fixes: 1a1c130ab757 ("ACPI: tables: x86: Reserve memory occupied by ACPI tables")
> > > Reported-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> > > Tested-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> > > ---
> > >
> > > George, can you please check if this reintroduces the issue addressed by
> > > the above commit for you?
> > >
> > > ---
> > >    arch/x86/kernel/setup.c |    5 ++---
> > >    1 file changed, 2 insertions(+), 3 deletions(-)
> > >
> > > Index: linux-pm/arch/x86/kernel/setup.c
> > > ===================================================================
> > > --- linux-pm.orig/arch/x86/kernel/setup.c
> > > +++ linux-pm/arch/x86/kernel/setup.c
> > > @@ -1045,9 +1045,6 @@ void __init setup_arch(char **cmdline_p)
> > >
> > >        cleanup_highmap();
> > >
> > > -     /* Look for ACPI tables and reserve memory occupied by them. */
> > > -     acpi_boot_table_init();
> > > -
> > >        memblock_set_current_limit(ISA_END_ADDRESS);
> > >        e820__memblock_setup();
> > >
> > > @@ -1132,6 +1129,8 @@ void __init setup_arch(char **cmdline_p)
> > >        reserve_initrd();
> > >
> > >        acpi_table_upgrade();
> > > +     /* Look for ACPI tables and reserve memory occupied by them. */
> > > +     acpi_boot_table_init();
> > >
> > >        vsmp_init();
> >
> > This is fairly late; especially, it's after actual allocations -- see
> > e820__memblock_alloc_reserved_mpc_new().
> >
> > Can't the table upgrade mechanism fix up when adjusting something?
>
> Not at this point of the cycle I'm afraid.
>
> > Some details on what actually breaks would be helpful.
>
> Generally speaking, the table overrides that come from the initrd are
> not taken into account if acpi_boot_table_init() runs before
> acpi_table_upgrade() and the latter cannot run before
> reserve_initrd().

I see. (looking at Documentation/acpi/initrd_table_override.txt I 
understand what acpi table overrides are for :) )

> Honestly, I'm not sure how much effort it would take to untangle this ATM.

Also true; ideally, we wouldn't have any allocations (find+reserve) 
before ordinary reservations are done.

However, I have no idea if we can move 
e820__memblock_alloc_reserved_mpc_new() and reserve_real_mode() around 
easily. Also, reserve_initrd()->relocate_initrd() does allocations.

This is a mess.

--
Thanks,

David / dhildenb