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Message-ID: <54B3E1AC.6080902@citrix.com>
Date: Mon, 12 Jan 2015 15:01:00 +0000
From: David Vrabel <david.vrabel@...rix.com>
To: Jiang Liu <jiang.liu@...ux.intel.com>,
Sander Eikelenboom <linux@...elenboom.it>,
Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, <x86@...nel.org>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
David Vrabel <david.vrabel@...rix.com>,
"Grant Likely" <grant.likely@...aro.org>,
Yinghai Lu <yinghai@...nel.org>
CC: <xen-devel@...ts.xenproject.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [Xen-devel] [PATCH v2] [Bugfix] x86/apic: Fix xen IRQ allocation
failure caused by commit b81975eade8c
On 12/01/15 13:39, Jiang Liu wrote:
> Commit b81975eade8c ("x86, irq: Clean up irqdomain transition code")
> breaks xen IRQ allocation because xen_smp_prepare_cpus() doesn't invoke
> setup_IO_APIC(), so no irqdomains created for IOAPICs and
> mp_map_pin_to_irq() fails at the very beginning.
>
> Enhance xen_smp_prepare_cpus() to call setup_IO_APIC() to initialize
> irqdomain for IOAPICs.
Having Xen call setup_IO_APIC() to initialize the irq domains then having to
add special cases to it is just wrong.
The bits of init deferred by mp_register_apic() are also deferred to
two different places which looks odd.
What about something like the following (untested) patch?
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 3f5f604..e180680 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -253,8 +253,10 @@ int __init arch_early_ioapic_init(void)
if (!nr_legacy_irqs())
io_apic_irqs = ~0UL;
- for_each_ioapic(i)
+ for_each_ioapic(i) {
+ BUG_ON(mp_irqdomain_create(ioapic));
alloc_ioapic_saved_registers(i);
+ }
/*
* For legacy IRQ's, start with assigning irq0 to irq15 to
@@ -2379,8 +2381,6 @@ void __init setup_IO_APIC(void)
io_apic_irqs = nr_legacy_irqs() ? ~PIC_IRQS : ~0UL;
apic_printk(APIC_VERBOSE, "ENABLING IO-APIC IRQs\n");
- for_each_ioapic(ioapic)
- BUG_ON(mp_irqdomain_create(ioapic));
/*
* Set up IO-APIC IRQ routing.
@@ -2929,7 +2929,8 @@ int mp_register_ioapic(int id, u32 address, u32 gsi_base,
/*
* If mp_register_ioapic() is called during early boot stage when
* walking ACPI/SFI/DT tables, it's too early to create irqdomain,
- * we are still using bootmem allocator. So delay it to setup_IO_APIC().
+ * we are still using bootmem allocator. So delay it to
+ * arch_early_ioapic_init().
*/
if (hotplug) {
if (mp_irqdomain_create(idx)) {
> --- a/arch/x86/kernel/apic/io_apic.c
> +++ b/arch/x86/kernel/apic/io_apic.c
> @@ -2369,6 +2381,15 @@ static void ioapic_destroy_irqdomain(int idx)
> ioapics[idx].pin_info = NULL;
> }
>
> +static void setup_IO_APIC_IDs(void)
> +{
> + if (xen_domain())
> + return;
This would have to xen_pv_domain().
David
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