Re: [RFC PATCH 0/6] Unify the Interrupt Mode and setup it as soon as possible

[Dou Liyang]

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@xxxxxxxxxx, not joro@xxxxxxxxxx

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