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Subject[PATCH v9 00/12] Unify the interrupt delivery mode and do its setup in advance
Date
Changes V8 --> V9:
No functionality change, update and modify the comments.

- [01/12] patch: modify the comments of apic_intr_mode_select().
Currently, the check logic of BIOS is based on the original code,
Baoquan and I have discussed it in V8 for readability, I am not sure
that I can clean up it correctly, So keep it like before.

- [06/12] patch: update the comments of init_apic_mappings()

- [11/12] patch: update the comments of native_smp_prepare_cpus().

- Post the patch putting acpi_early_init() earlier independently
suggested by Rafael and Baoquan.

- Rebase it

[Background]

MP specification defines three different interrupt delivery modes as follows:

1. PIC Mode
2. Virtual Wire Mode
3. Symmetric I/O Mode

They will be setup in the different periods of booting time:
1. *PIC Mode*, the default interrupt delivery modes, will be set first.
2. *Virtual Wire Mode* will be setup during ISA IRQ initialization( step 1
in the figure.1).
3. *Symmetric I/O Mode*'s setup is related to the system
3.1 In SMP-capable system, setup during prepares CPUs(step 2)
3.2 In UP system, setup during 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 |
+-------------------+
figure.1 The flow chart of the kernel startup process

[Problem]

1. Cause kernel in an unmatched mode at the beginning of booting time.
2. Cause the dump-capture kernel hangs with 'notsc' option inherited
from 1st kernel option.
3. Cause the code hard to read and maintain.

As Ingo's and Eric's discusses[1,2], it need to be refactor.

[Solution]

1. Construct a selector to unify these switches

+------------+
|disable_apic+--------------------+
+------------+ true |
|false |
| |
+------------v------------------+ |
|!boot_cpu_has(X86_FEATURE_APIC)+-------+
+-------------------------------+ true |
|false |
| |
+-------v---------+ v
|!smp_found_config| PIC MODE
+---------------+-+
|false |true
| |
v +---v---------+
SYMMETRIC IO MODE | !acpi_lapic |
+------+------+
|
v
VIRTUAL WIRE MODE

2. Unifying these setup steps of SMP-capable and UP system

start_kernel
---------------+
|
|
|
| x86_late_time_init
+---->---+------------+
| |
| | +------------------------+
| +----> | 4. init_interrupt_mode |
| +------------------------+
v


3. Execute the function as soon as possible.

[Link]

[1]. https://lkml.org/lkml/2016/8/2/929
[2]. https://lkml.org/lkml/2016/8/1/506

[History patches]
For previous discussion, please refer to:

V8: https://lkml.org/lkml/2017/8/27/265
V7: https://lkml.org/lkml/2017/7/14/20
V6: https://lkml.org/lkml/2017/7/3/269
V5: https://lkml.org/lkml/2017/6/30/17
V3: https://lkml.org/lkml/2017/5/10/323
V2: https://www.spinics.net/lists/kernel/msg2491620.html
V1: https://lkml.org/lkml/2017/3/29/481


Changes V7 --> V8:

- Change the order of [12/13] patch and [11/13]patch suggested by Rafael J. Wysocki.
- Fix some comments.
- Do more tests in Thinkpad x121e -- Thanks for Borislav Petkov's help.

Changes V6 --> V7:

- add a new patch: p12

Changes V5 --> V6:

- change the check order for X86_32 in apic_intr_mode_select()
- replace the apic_printk with pr_info in apic_intr_mode_init()
- add a separate helper function for get the logical apicid
- remove the extra argument upmode in apic_intr_mode_select()
- cleanup the logic of apic_intr_mode_init()
- replcae the 'ticks = jiffies' with 'end = jiffies + 4'
- rewrite the 9th and 10th patches's changelog

Changes V4 --> V5:

- remove the RFC presix
- remove the 1/12 patch in V4
- merge 2 patches together for SMP-capable system
- replace the *_interrupt_* with *_intr_*
- replace the pr_info with apic_printk in apic_intr_mode_init()
- add a patch for PV xen to bypass intr_mode_init()

Changes V3 --> V4:

- Move interrupt_mode_init to x86_init_ops instead of the use of
header files
- Replace "return" with "break" in case of APIC_SYMMETRIC_IO_NO_ROUTING
- Setup upmode earlier for UP system.
- Check interrupt mode before per cpu clock event setup.

Changes V2 --> V3:

- Rebase the patches.
- Change two function name:
apic_bsp_mode_check --> apic_interrupt_mode_select
init_interrupt_mode --> apic_interrupt_mode_init
- Find a new waiting way to check whether timer IRQs work or not
- Refine the switch logic in apic_interrupt_mode_init()
- Consistently start sentences with upper case letters
- Fix some typos and comments
- Try my best to rewrite some changelog again

Changes since V1:

- Move the initialization from init_IRQ() to x86_late_time_init()
- Use a threshold to refactor the check logic in timer_irq_works()
- Rename the framework to a selector
- Split two patches
- Consistently start sentences with upper case letters
- Fix some typos
- Rewrite the changelog

Cc: xen-devel@lists.xenproject.org
Cc: boris.ostrovsky@oracle.com
Cc: Juergen Gross <jgross@suse.com>
Cc: linux-acpi@vger.kernel.org
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Zheng, Lv <lv.zheng@intel.com>

Dou Liyang (12):
x86/apic: Construct a selector for the interrupt delivery mode
x86/apic: Prepare for unifying the interrupt delivery modes setup
x86/apic: Split local APIC timer setup from the APIC setup
x86/apic: Move logical APIC ID away from apic_bsp_setup()
x86/apic: Unify interrupt mode setup for SMP-capable system
x86/apic: Mark the apic_intr_mode extern for sanity check cleanup
x86/apic: Unify interrupt mode setup for UP system
x86/ioapic: Refactor the delay logic in timer_irq_works()
x86/init: add intr_mode_init to x86_init_ops
x86/xen: Bypass intr mode setup in enlighten_pv system
x86/time: Initialize interrupt mode behind timer init
x86/apic: Remove the init_bsp_APIC()

arch/x86/include/asm/apic.h | 15 +++-
arch/x86/include/asm/x86_init.h | 2 +
arch/x86/kernel/apic/apic.c | 188 ++++++++++++++++++++--------------------
arch/x86/kernel/apic/io_apic.c | 45 +++++++++-
arch/x86/kernel/irqinit.c | 3 -
arch/x86/kernel/smpboot.c | 85 ++++++------------
arch/x86/kernel/time.c | 5 ++
arch/x86/kernel/x86_init.c | 1 +
arch/x86/xen/enlighten_pv.c | 1 +
9 files changed, 184 insertions(+), 161 deletions(-)

--
2.5.5



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