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Message-ID: <1d5f96d4-a443-e63b-e50c-f89ab7469e1f@cn.fujitsu.com>
Date: Thu, 30 Mar 2017 11:09:56 +0800
From: Dou Liyang <douly.fnst@...fujitsu.com>
To: Baoquan He <bhe@...hat.com>
CC: <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
<tglx@...utronix.de>, <mingo@...nel.org>, <ebiederm@...ssion.com>,
<hpa@...or.com>, <izumi.taku@...fujitsu.com>, <joro@...tes.org>
Subject: Re: [RFC PATCH 0/6] Unify the Interrupt Mode and setup it as soon as
possible
At 03/30/2017 11:03 AM, Dou Liyang wrote:
> Hi Baoquan,
>
> At 03/30/2017 10:08 AM, Baoquan He wrote:
>> Hi Liyang,
>>
>> This is awesome. I planned to do this after kaslr back porting, glad to
>> see your posting. I like below diagram and the idea of patch 2/6
>> framework. Will review and see what I can do to help since rhel bug from
>> FJ is assigned to me.
>>
>
> Thanks very much for your join! We have investigated the bug almost
> half a year. :)
>
> In my opinion,
> If we plan to refactor the process of APIC initialization for the bug.
> There must be lots of work need to be done. This patchset is just the
> first step. When I test it, I am thinking about:
>
> 1. The check and logic in each enable and setup LAPIC/IOAPIC functions.
> 2. The process of IRQ remapping.
> 3. The check and init of APIC timer.
> 4. The relationship between the various switches, such as If
> the smp_found_config is 1, the acpi_lapic must be 1.
>
> And following work to me are:
>
> 1. Use more test cases to test.
> 2. learn the IOMMU.
> 3. trace the APIC timer code.
> 4. make the check logic more clear.
>
> Hope to be helpful to you.
>
>> Thanks for the effort!
>>
>> And add Joerg to this thread since he knows IOMMU very well.
>
ahh,
--cc joro@...tes.org, not joro@...pes.org
Thanks
Liyang
> oops, Yes, I forgot it, Thanks!
>
> Thanks
> Liyang
>
>>
>> Thanks
>> Baoquan
>>
>> On 03/29/17 at 10:55pm, Dou Liyang wrote:
>>> According to Ingo's and Eric's advice[1,2], Try my best to optimize the
>>> init of Interrupt Mode for x86.
>>>
>>> The MP specification defines three different interrupt modes as follows:
>>>
>>> 1. PIC Mode
>>> 2. Virtual Wire Mode
>>> 3. Symmetic I/O Mode
>>>
>>> Currently, In kernel,
>>>
>>> 1. Setup the Virtual Wire Mode during the IRQ initialization(
>>> step 1 in the following figure).
>>> 2. Enable and Setup the Symmetic I/O Mode either during the
>>> SMP-capabe system prepares CPUs(step 2) or during the UP system
>>> initializes itself(step 3).
>>>
>>> start_kernel
>>> +---------------+
>>> |
>>> +--> .......
>>> |
>>> | setup_arch
>>> +--> +-------+
>>> |
>>> | init_IRQ
>>> +-> +--+-----+
>>> | | init_ISA_irqs
>>> | +------> +-+--------+
>>> | | +----------------+
>>> +---> +------> | 1.init_bsp_APIC|
>>> | ....... +----------------+
>>> +--->
>>> | rest_init
>>> +--->---+-----+
>>> | | kernel_init
>>> | +> ----+-----+
>>> | | kernel_init_freeable
>>> | +-> ----+-------------+
>>> | | smp_prepare_cpus
>>> | +---> +----+---------+
>>> | | | +-------------------+
>>> | | +-> |2. apic_bsp_setup |
>>> | | +-------------------+
>>> | |
>>> v | smp_init
>>> +---> +---+----+
>>> | +-------------------+
>>> +--> |3. apic_bsp_setup |
>>> +-------------------+
>>>
>>> The purpose of this patchset is Unifing these setup steps and
>>> executing as
>>> soon as possible as follows:
>>>
>>> start_kernel
>>> ---------------+
>>> |
>>> |
>>> |
>>> | init_IRQ
>>> +---->---+----+
>>> | |
>>> | | +--------------------+
>>> | +----> | 4. init_bsp_APIC |
>>> | +--------------------+
>>> v
>>>
>>> By the way, Also fix a bug about kexec[3].
>>>
>>>
>>> Some doubts, need help:
>>>
>>> 1. Patchset has influence on IOMMU in enable_IR_x2apic(). Not sure
>>> it can be in advance?
>>>
>>> 2. Due to
>>>
>>> Commit 8c3ba8d04924 ("x86, apic: ack all pending irqs when crashed/on
>>> kexec")
>>>
>>> ..., patchset also needs TSC and uses the "cpu_khz" in
>>> setup_local_APIC().
>>> And a warning[4] will be triggered when crashed/on kexec. Not sure
>>> how to
>>> modify?
>>>
>>> [1]. https://lkml.org/lkml/2016/8/2/929
>>> [2]. https://lkml.org/lkml/2016/8/1/506
>>> [3]. https://lkml.org/lkml/2016/7/25/1118
>>> [4]. WARN_ON(max_loops <= 0) in setup_local_APIC()
>>>
>>> Dou Liyang (6):
>>> x86/apic: Replace init_bsp_APIC() with apic_virture_wire_mode_setup()
>>> x86/apic: Construct a framework for setuping APIC mode as soon as
>>> possible
>>> x86/apic: Extract APIC timer related code from apic_bsp_setup()
>>> x86/apic: Make the APIC mode setup earlier for SMP-capable system
>>> x86/apic: Make the APIC mode setup earlier for UP system
>>> x86/apic: Remove the apic_virture_wire_mode_setup()
>>>
>>> arch/x86/include/asm/apic.h | 7 +-
>>> arch/x86/include/asm/io_apic.h | 2 +
>>> arch/x86/kernel/apic/apic.c | 218
>>> ++++++++++++++++++++++++-----------------
>>> arch/x86/kernel/apic/io_apic.c | 4 +-
>>> arch/x86/kernel/irqinit.c | 6 +-
>>> arch/x86/kernel/smpboot.c | 68 ++-----------
>>> 6 files changed, 149 insertions(+), 156 deletions(-)
>>>
>>> --
>>> 2.5.5
>>>
>>>
>>>
>>
>>
>>
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