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Date:	Wed, 17 Dec 2014 12:35:31 +0800
From:	Jiang Liu <>
To:	Thomas Gleixner <>,
	Joerg Roedel <>,
	Benjamin Herrenschmidt <>,
	Ingo Molnar <>,
	"H. Peter Anvin" <>, Yinghai Lu <>,
	Borislav Petkov <>
Cc:	Jiang Liu <>,
	Tony Luck <>,,,
Subject: [Patch v1 00/17] Refine IR initialization flow and fixes bugs related to X2APIC

When converting x86 to new hierarchy irqdoamin framework, Thomas noticed
that the interrupt remapping initialization flow is a little complex and
has troubles in memory allocation. Then there is a joint force to
simplify IR initialization flow, please refer to related threads at:

This patch set is based on latest mainstream kernel and I will rebased
it onto v3.19-rc1 once v3.19-rc1 is out. And you may access it at: ir_init_v1

This patch set combimes above three patches to simplify IR initalization
flow and solves memory allocation issues. While at it, this patch set
also refines CPU X2APIC initialization code for maintenance. It also
fixes two bugs related to X2APIC support.
1) System hangs or panics if BIOS enables CPU X2APIC mode but kernel
   doesn't support X2APIC.
2) System livelocks if BIOS enables CPU X2APIC but opt-outs IR X2APIC.

This patch set has been tested with on an Intel 4-socket system with
following configuration:
[CPU X2APIC]	[IR X2APIC]	[Linux IR]	[Linux X2APIC]	[Result]
1     D		    /		    D		    D		  OK
2     D		    /		    E		    D		  OK
3     D		    /		    E		    E		  OK
4     P		    /		    E		    E		  OK
5     P		    /		    D		    D		  Panic(expected)
6     P		    /		    E		    D		  Panic(expected)
7     P		    H		    E		    E		  OK
CPU X2APIC: whether CPU X2APIC is enabled by hardware and BIOS
IR X2APIC: whether interrupt remapping hardware supports X2APIC mode
Linux IR: whether interrupt remapping is enabled by Linux kernel
Linux X2APIC: whether X2APIC is supported by Linux kernel
D: disabled
E: enabled
/: Not care
P: CPU X2APIC pre-enabled by BIOS
H: Hard-coded to opt-out X2APIC support in interrupt remapping hardware

The patch set changes the behevior of the last three rows:
1) Row 5 and 6 panics with clear messages instead of random hang or panic.
2) Row 7 boots successfully instead of livelocking.

The patch set also passes Fengguang's 0day test suites.

Due to lack of hardware platforms for tests, tests on AMD platform are

Jiang Liu (11):
  x86/apic: Panic if kernel doesn't support x2apic but BIOS has enabled
  x86/apic: Kill useless variable x2apic_enabled in function
  x86/apic: Correctly detect X2APIC status in function enable_IR()
  x86/apic: Refine enable_IR_x2apic() and related functions
  iommu/vt-d: Prepare for killing function irq_remapping_supported()
  iommu/vt-d: Allow IR works in XAPIC mode though CPU works in X2APIC
  x86/apic: Only disable CPU x2apic mode when necessary
  iommu/irq_remapping: Kill function irq_remapping_supported() and
    related code
  iommu/irq_remapping: Refine function irq_remapping_prepare() for
  iommu/irq_remapping: Change variable disable_irq_remap to be static
  iommu/irq_remapping: Normailize the way to detect whether IR is

Joerg Roedel (2):
  iommu/vt-d: Allocate IRQ remapping data structures only for all
  iommu/amd: Check for irq-remap support amd_iommu_prepare()

Thomas Gleixner (4):
  x86, smpboot: Remove pointless preempt_disable() in
  iommu, x86: Restructure setup of the irq remapping feature
  iommu/vt-d: Move iommu preparatory allocations to
  iommu/vt-d: Convert allocations to GFP_KERNEL

 arch/x86/include/asm/irq_remapping.h |    4 --
 arch/x86/kernel/apic/apic.c          |  104 ++++++++++++++++------------------
 arch/x86/kernel/smpboot.c            |    8 +--
 drivers/iommu/amd_iommu.c            |    1 -
 drivers/iommu/amd_iommu_init.c       |   10 +---
 drivers/iommu/amd_iommu_proto.h      |    1 -
 drivers/iommu/intel_irq_remapping.c  |   96 ++++++++++++++++---------------
 drivers/iommu/irq_remapping.c        |   74 ++++++++----------------
 drivers/iommu/irq_remapping.h        |    5 --
 9 files changed, 129 insertions(+), 174 deletions(-)


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