linux-kernel - Re: [PATCH 0/5] Fix Intel IRQ remapping initialization order

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Date:	Tue, 16 Dec 2014 09:45:14 +0800
From:	Jiang Liu <jiang.liu@...ux.intel.com>
To:	Thomas Gleixner <tglx@...utronix.de>
CC:	Joerg Roedel <joro@...tes.org>, Ingo Molnar <mingo@...hat.com>,
	hpa@...or.com, x86@...nel.org, Borislav Petkov <bp@...en8.de>,
	linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org
Subject: Re: [PATCH 0/5] Fix Intel IRQ remapping initialization order



On 2014/12/16 3:54, Thomas Gleixner wrote:
> On Mon, 15 Dec 2014, Jiang Liu wrote:
>> On 2014/12/15 23:13, Joerg Roedel wrote:
>>> Hi,
>>>
>>> here is a patch-set against tip/x86/apic to fix an initialization order
>>> problem with the IRQ remapping code.  The problem is in the ordering of
>>> the irq_remapping_prepare and irq_remapping_supported functions.
>>>
>>> Currently the call-order is irq_remapping_prepare ->
>>> irq_remapping_supported, so that 'prepare' can succeed but 'supported'
>>> fails, so that interrupt remapping gets initialized but not enabled.
>>> This causes a broken interrupt setup on affected systems (machines with
>>> an Intel IOMMU without, or broken, IRQ remapping support). The result
>>> are lost interrupts and a non-bootable system.
>>>
>>> Both functions do checks whether IRQ remapping can be enabled on the
>>> machine.  The reason for this is that some checks rely on
>>> dmar_table_init() and thus have to be done in irq_remapping_prepare().
>>>
>>> This patch-set moves all these checks into the irq_remapping_prepare()
>>> path with the right ordering and removes the irq_remapping_supported()
>>> function and its call-backs. This fixes the initializion order problem
>>> and simplifies the exported API from the IOMMU code.
>>>
>>> Please review.
>> Hi Joerg,
>> 	I have posted a patch set for the same purpose at:
>> https://lkml.org/lkml/2014/12/10/20
>> 	Seems we need to combine these two patch sets:)
> 
> Actually you want to combine it also with these patches:
> 
> 326c2bb2c526: iommu/vt-d: Convert allocations to GFP_KERNEL
> e9220e591375: iommu/vt-d: Move iommu preparatory allocations to irq_remap_ops.prepare
> e88edbd316ea: iommu, x86: Restructure setup of the irq remapping feature
> dd60143c04f2: x86, smpboot: Remove pointless preempt_disable() in native_smp_prepare_cpus()
> 
> against 3.19 independent of the irqdomain stuff.
> 
> So that would be a clean base to put the rest of the irqdomain and
> hotplug stuff on top.
> 
> So the ordering of the patches for 3.20 would become:
> 
>    iommu cleanup (init and allocations)
>    acpi cleanup and parser extensions
>    ioapic hotplug
>    irqdomain conversion
> 
> I will route dd60143c04f2 "x86, smpboot: Remove pointless
> preempt_disable() in native_smp_prepare_cpus()" into -rc1.  I'm going
> to do so for a few other cherry-picks from x86/apic.
> 
> So can you please create a combined series, which just deals with the
> init cleanup and the allocation conversion (ATOMIC -> GFP) based on
> current Linus tree should be fine.
Hi Thomas,
	I will work on that, hope we will have something after Christmas Holiday:)
Regards!
Gerry
> 
> Thanks,
> 
> 	tglx
> 
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