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Re: 4.8.2 not booting in 32-bit VM without I/O-APIC

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  Re: 4.8.2 not booting in 32-bit VM without I/O-APIC Michal Necasek <michal.necasek@oracle.com> - 2016-11-03 21:10 +0100
    Re: 4.8.2 not booting in 32-bit VM without I/O-APIC Michael Thayer <michael.thayer@oracle.com> - 2016-11-10 15:30 +0100
      Re: 4.8.2 not booting in 32-bit VM without I/O-APIC Thomas Gleixner <tglx@linutronix.de> - 2016-11-10 18:30 +0100

#1514811 — Re: 4.8.2 not booting in 32-bit VM without I/O-APIC

    Hi Thomas,

 Sorry for the delay. I can confirm that the problem is fixed in 4.9.0-rc3 and prefill_possible_map no longer crashes (as it did in 4.9.0-rc2). Thank you!

 Just a side question, is the previous fix in commit ff8560512b (x86/boot/smp: Don't try to poke disabled/non-existent APIC) actually still required or would the no-op APIC driver take care of it?

    Regards,
      Michal

----- Original Message -----
From: tglx@linutronix.de
To: michal.necasek@oracle.com
Cc: prarit@redhat.com, ville.syrjala@linux.intel.com, michael.thayer@oracle.com, knut.osmundsen@oracle.com, frank.mehnert@oracle.com, linux-kernel@vger.kernel.org
Sent: Friday, October 28, 2016 9:37:31 PM GMT +01:00 Amsterdam / Berlin / Bern / Rome / Stockholm / Vienna
Subject: Re: 4.8.2 not booting in 32-bit VM without I/O-APIC

On Fri, 28 Oct 2016, Thomas Gleixner wrote:

> On Fri, 28 Oct 2016, Michal Necasek wrote:
> > 
> >  Sorry if I wasn't clear. No, it doesn't work for us. The ff8560512b8d
> > commit fixes the APIC poking on machines where there is no local APIC
> > available (and thus fixes the committer's machine), but it doesn't work
> > in our case, where there is a local APIC but no I/O APIC, no ACPI MADT,
> > and no MP tables.
> 
> > In other words, for us boot_cpu_has(X86_FEATURE_APIC) is true but the
> > APIC has not been set up yet because init_apic_mappings() hasn't been
> > run.

Right. That mapping setup is an utter trainwreck as we do it from multiple
places, but there is no reason why we can't move it before the call to
prefill_possible_map().

Thanks,

	tglx

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index bbfbca5fea0c..b59fdba3cbdf 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1221,11 +1221,13 @@ void __init setup_arch(char **cmdline_p)
 	 */
 	get_smp_config();
 
+	/* Make sure apic is mapped before prefill_possible_map() */
+	init_apic_mappings();
+
 	prefill_possible_map();
 
 	init_cpu_to_node();
 
-	init_apic_mappings();
 	io_apic_init_mappings();
 
 	kvm_guest_init();

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#1519008

Hello,

On 03.11.2016 21:02, Michal Necasek wrote:
> Sorry for the delay. I can confirm that the problem is fixed in
> 4.9.0-rc3 and prefill_possible_map no longer crashes (as it did in
> 4.9.0-rc2). Thank you!
>
> Just a side question, is the previous fix in commit ff8560512b
> (x86/boot/smp: Don't try to poke disabled/non-existent APIC) actually
> still required or would the no-op APIC driver take care of it?

Sorry for the delay too (holiday-related).  I tested 4.9.0rc4 on a 
32-bit VirtualBox virtual machine without I/O-APIC and can confirm that 
it now boots.  Since I am at it, the OHCI timer wheel-related problems 
are also no longer reproducible.

Regards and thanks,

Michael

>
> Regards, Michal
>
> ----- Original Message ----- From: tglx@linutronix.de To:
> michal.necasek@oracle.com Cc: prarit@redhat.com,
> ville.syrjala@linux.intel.com, michael.thayer@oracle.com,
> knut.osmundsen@oracle.com, frank.mehnert@oracle.com,
> linux-kernel@vger.kernel.org Sent: Friday, October 28, 2016 9:37:31
> PM GMT +01:00 Amsterdam / Berlin / Bern / Rome / Stockholm / Vienna
> Subject: Re: 4.8.2 not booting in 32-bit VM without I/O-APIC
>
> On Fri, 28 Oct 2016, Thomas Gleixner wrote:
>
>> On Fri, 28 Oct 2016, Michal Necasek wrote:
>>>
>>> Sorry if I wasn't clear. No, it doesn't work for us. The
>>> ff8560512b8d commit fixes the APIC poking on machines where there
>>> is no local APIC available (and thus fixes the committer's
>>> machine), but it doesn't work in our case, where there is a local
>>> APIC but no I/O APIC, no ACPI MADT, and no MP tables.
>>
>>> In other words, for us boot_cpu_has(X86_FEATURE_APIC) is true but
>>> the APIC has not been set up yet because init_apic_mappings()
>>> hasn't been run.
>
> Right. That mapping setup is an utter trainwreck as we do it from
> multiple places, but there is no reason why we can't move it before
> the call to prefill_possible_map().
>
> Thanks,
>
> tglx
>
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index
> bbfbca5fea0c..b59fdba3cbdf 100644 --- a/arch/x86/kernel/setup.c +++
> b/arch/x86/kernel/setup.c @@ -1221,11 +1221,13 @@ void __init
> setup_arch(char **cmdline_p) */ get_smp_config();
>
> +	/* Make sure apic is mapped before prefill_possible_map() */ +
> init_apic_mappings(); + prefill_possible_map();
>
> init_cpu_to_node();
>
> -	init_apic_mappings(); io_apic_init_mappings();
>
> kvm_guest_init();
>

-- 
Michael Thayer | VirtualBox engineer
ORACLE Deutschland B.V. & Co. KG | Werkstr. 24 | D-71384 Weinstadt

ORACLE Deutschland B.V. & Co. KG
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der Handelskammer Midden-Nederland, Nr. 30143697
Geschäftsführer: Alexander van der Ven, Jan Schultheiss, Val Maher

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#1519170

On Thu, 10 Nov 2016, Michael Thayer wrote:
> On 03.11.2016 21:02, Michal Necasek wrote:
> > Sorry for the delay. I can confirm that the problem is fixed in
> > 4.9.0-rc3 and prefill_possible_map no longer crashes (as it did in
> > 4.9.0-rc2). Thank you!
> > 
> > Just a side question, is the previous fix in commit ff8560512b
> > (x86/boot/smp: Don't try to poke disabled/non-existent APIC) actually
> > still required or would the no-op APIC driver take care of it?
> 
> Sorry for the delay too (holiday-related).  I tested 4.9.0rc4 on a 32-bit

No problem. I hope you enjoyed your well earned vacation :)

> VirtualBox virtual machine without I/O-APIC and can confirm that it now boots.
> Since I am at it, the OHCI timer wheel-related problems are also no longer
> reproducible.

Thanks for reporting back!

       tglx

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