[Patch v1 00/17] Refine IR initialization flow and fixes bugs related to X2APIC

[Patch v1 00/17] Refine IR initialization flow and fixes bugs related to X2APIC

[Jiang Liu]

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:
https://lkml.org/lkml/2014/12/5/114
https://lkml.org/lkml/2014/12/10/20
https://www.mail-archive.com/linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org/msg788792.html

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:
https://github.com/jiangliu/linux.git 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
welcomed!

Jiang Liu (11):
  x86/apic: Panic if kernel doesn't support x2apic but BIOS has enabled
    x2apic
  x86/apic: Kill useless variable x2apic_enabled in function
    enable_IR_x2apic()
  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
    mode
  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
    maintenance
  iommu/irq_remapping: Change variable disable_irq_remap to be static
  iommu/irq_remapping: Normailize the way to detect whether IR is
    enabled

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

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

-- 
1.7.10.4

[Patch v1 01/17] x86, smpboot: Remove pointless preempt_disable() in native_smp_prepare_cpus()

[Jiang Liu]

From: Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>

There is no reason to keep preemption disabled in this function.

We only have two other threads live: kthreadd and idle. Neither of
them is going to preempt. But that preempt_disable forces all the code
inside to do GFP_ATOMIC allocations which is just insane.

Remove it.

Signed-off-by: Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
Tested-by: Borislav Petkov <bp-Gina5bIWoIWzQB+pC5nmwQ@public.gmane.org>
Cc: Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Cc: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
Cc: x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org
Link: http://lkml.kernel.org/r/20141205084147.153643952-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org
Signed-off-by: Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
Signed-off-by: Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 arch/x86/kernel/smpboot.c |    8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 7a8f5845e8eb..6d7022c683e3 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1084,7 +1084,6 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
 {
 	unsigned int i;
 
-	preempt_disable();
 	smp_cpu_index_default();
 
 	/*
@@ -1102,22 +1101,19 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
 	}
 	set_cpu_sibling_map(0);
 
-
 	if (smp_sanity_check(max_cpus) < 0) {
 		pr_info("SMP disabled\n");
 		disable_smp();
-		goto out;
+		return;
 	}
 
 	default_setup_apic_routing();
 
-	preempt_disable();
 	if (read_apic_id() != boot_cpu_physical_apicid) {
 		panic("Boot APIC ID in local APIC unexpected (%d vs %d)",
 		     read_apic_id(), boot_cpu_physical_apicid);
 		/* Or can we switch back to PIC here? */
 	}
-	preempt_enable();
 
 	connect_bsp_APIC();
 
@@ -1151,8 +1147,6 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
 		uv_system_init();
 
 	set_mtrr_aps_delayed_init();
-out:
-	preempt_enable();
 }
 
 void arch_enable_nonboot_cpus_begin(void)
-- 
1.7.10.4

[Patch v1 02/17] iommu, x86: Restructure setup of the irq remapping feature

[Jiang Liu]

From: Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>

enable_IR_x2apic() calls setup_irq_remapping_ops() which by default
installs the intel dmar remapping ops and then calls the amd iommu irq
remapping prepare callback to figure out whether we are running on an
AMD machine with irq remapping hardware.

Right after that it calls irq_remapping_prepare() which pointlessly
checks:
	if (!remap_ops || !remap_ops->prepare)
               return -ENODEV;
and then calls

    remap_ops->prepare()

which is silly in the AMD case as it got called from
setup_irq_remapping_ops() already a few microseconds ago.

Simplify this and just collapse everything into
irq_remapping_prepare().

The irq_remapping_prepare() remains still silly as it assigns blindly
the intel ops, but that's not scope of this patch.

The scope here is to move the preperatory work, i.e. memory
allocations out of the atomic section which is required to enable irq
remapping.

Signed-off-by: Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
Tested-by: Borislav Petkov <bp-Gina5bIWoIWzQB+pC5nmwQ@public.gmane.org>
Acked-by: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
Cc: Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Cc: x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org
Link: http://lkml.kernel.org/r/20141205084147.232633738-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org
Signed-off-by: Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
Signed-off-by: Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 arch/x86/include/asm/irq_remapping.h |    2 --
 arch/x86/kernel/apic/apic.c          |    3 ---
 drivers/iommu/irq_remapping.c        |   19 +++++++------------
 3 files changed, 7 insertions(+), 17 deletions(-)

diff --git a/arch/x86/include/asm/irq_remapping.h b/arch/x86/include/asm/irq_remapping.h
index b7747c4c2cf2..f1b619e5a50d 100644
--- a/arch/x86/include/asm/irq_remapping.h
+++ b/arch/x86/include/asm/irq_remapping.h
@@ -33,7 +33,6 @@ struct irq_cfg;
 
 #ifdef CONFIG_IRQ_REMAP
 
-extern void setup_irq_remapping_ops(void);
 extern int irq_remapping_supported(void);
 extern void set_irq_remapping_broken(void);
 extern int irq_remapping_prepare(void);
@@ -60,7 +59,6 @@ void irq_remap_modify_chip_defaults(struct irq_chip *chip);
 
 #else  /* CONFIG_IRQ_REMAP */
 
-static inline void setup_irq_remapping_ops(void) { }
 static inline int irq_remapping_supported(void) { return 0; }
 static inline void set_irq_remapping_broken(void) { }
 static inline int irq_remapping_prepare(void) { return -ENODEV; }
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index ba6cc041edb1..5fd533a4c7a5 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1597,9 +1597,6 @@ void __init enable_IR_x2apic(void)
 	int ret, x2apic_enabled = 0;
 	int hardware_init_ret;
 
-	/* Make sure irq_remap_ops are initialized */
-	setup_irq_remapping_ops();
-
 	hardware_init_ret = irq_remapping_prepare();
 	if (hardware_init_ret && !x2apic_supported())
 		return;
diff --git a/drivers/iommu/irq_remapping.c b/drivers/iommu/irq_remapping.c
index 2c3f5ad01098..5829131aa34a 100644
--- a/drivers/iommu/irq_remapping.c
+++ b/drivers/iommu/irq_remapping.c
@@ -194,16 +194,6 @@ static __init int setup_irqremap(char *str)
 }
 early_param("intremap", setup_irqremap);
 
-void __init setup_irq_remapping_ops(void)
-{
-	remap_ops = &intel_irq_remap_ops;
-
-#ifdef CONFIG_AMD_IOMMU
-	if (amd_iommu_irq_ops.prepare() == 0)
-		remap_ops = &amd_iommu_irq_ops;
-#endif
-}
-
 void set_irq_remapping_broken(void)
 {
 	irq_remap_broken = 1;
@@ -222,9 +212,14 @@ int irq_remapping_supported(void)
 
 int __init irq_remapping_prepare(void)
 {
-	if (!remap_ops || !remap_ops->prepare)
-		return -ENODEV;
+	remap_ops = &intel_irq_remap_ops;
 
+#ifdef CONFIG_AMD_IOMMU
+	if (amd_iommu_irq_ops.prepare() == 0) {
+		remap_ops = &amd_iommu_irq_ops;
+		return 0;
+	}
+#endif
 	return remap_ops->prepare();
 }
 
-- 
1.7.10.4

[Patch v1 03/17] iommu/vt-d: Move iommu preparatory allocations to irq_remap_ops.prepare

[Jiang Liu]

From: Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>

The whole iommu setup for irq remapping is a convoluted mess. The
iommu detect function gets called from mem_init() and the prepare
callback gets called from enable_IR_x2apic() for unknown reasons.

Of course AMD and Intel setup differs in nonsensical ways. Intels
prepare callback is explicit while AMDs prepare callback is implicit
in setup_irq_remapping_ops() just to be called in the prepare call
again.

Because all of this gets called from enable_IR_x2apic() and the dmar
prepare function merily parses the ACPI tables, but does not allocate
memory we end up with memory allocation from irq disabled context
later on.

AMDs iommu code at least allocates the required memory from the
prepare function. That has issues as well, but thats not scope of this
patch.

The goal of this change is to distangle the allocation from the actual
enablement. There is no point to allocate memory from irq disabled
regions with GFP_ATOMIC just because it does not matter at that point
in the boot stage. It matters with physical hotplug later on.

There is another issue with the current setup. Due to the conversion
to stacked irqdomains we end up with a call into the irqdomain
allocation code from irq disabled context, but that code does
GFP_KERNEL allocations rightfully as there is no reason to do
preperatory allocations with GFP_ATOMIC.

That change caused the allocator code to complain about GFP_KERNEL
allocations invoked in atomic context. Boris provided a temporary
hackaround which changed the GFP flags if irq_domain_add() got called
from atomic context. Not pretty and we really dont want to get this
into a mainline release for obvious reasons.

Move the ACPI table parsing and the resulting memory allocations from
the enable to the prepare function. That allows to get rid of the
horrible hackaround in irq_domain_add() later.

[Jiang] Rebased onto v3.19

Signed-off-by: Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
Tested-by: Borislav Petkov <bp-Gina5bIWoIWzQB+pC5nmwQ@public.gmane.org>
Acked-by: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
Cc: Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Cc: x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org
Link: http://lkml.kernel.org/r/20141205084147.313026156-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org
Signed-off-by: Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
Signed-off-by: Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 drivers/iommu/intel_irq_remapping.c |   64 ++++++++++++++++++++++++-----------
 1 file changed, 44 insertions(+), 20 deletions(-)

diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
index 27541d440849..4b80e16e0736 100644
--- a/drivers/iommu/intel_irq_remapping.c
+++ b/drivers/iommu/intel_irq_remapping.c
@@ -595,22 +595,57 @@ static int __init intel_irq_remapping_supported(void)
 	return 1;
 }
 
-static int __init intel_enable_irq_remapping(void)
+static void __init intel_cleanup_irq_remapping(void)
+{
+	struct dmar_drhd_unit *drhd;
+	struct intel_iommu *iommu;
+
+	for_each_iommu(iommu, drhd) {
+		if (ecap_ir_support(iommu->ecap)) {
+			iommu_disable_irq_remapping(iommu);
+			intel_teardown_irq_remapping(iommu);
+		}
+	}
+
+	if (x2apic_supported())
+		pr_warn("Failed to enable irq remapping.  You are vulnerable to irq-injection attacks.\n");
+}
+
+static int __init intel_prepare_irq_remapping(void)
 {
 	struct dmar_drhd_unit *drhd;
 	struct intel_iommu *iommu;
-	bool x2apic_present;
-	int setup = 0;
-	int eim = 0;
 
-	x2apic_present = x2apic_supported();
+	if (dmar_table_init() < 0)
+		return -1;
 
 	if (parse_ioapics_under_ir() != 1) {
-		printk(KERN_INFO "Not enable interrupt remapping\n");
+		printk(KERN_INFO "Not enabling interrupt remapping\n");
 		goto error;
 	}
 
-	if (x2apic_present) {
+	for_each_iommu(iommu, drhd) {
+		if (!ecap_ir_support(iommu->ecap))
+			continue;
+
+		/* Do the allocations early */
+		if (intel_setup_irq_remapping(iommu))
+			goto error;
+	}
+	return 0;
+error:
+	intel_cleanup_irq_remapping();
+	return -1;
+}
+
+static int __init intel_enable_irq_remapping(void)
+{
+	struct dmar_drhd_unit *drhd;
+	struct intel_iommu *iommu;
+	int setup = 0;
+	int eim = 0;
+
+	if (x2apic_supported()) {
 		pr_info("Queued invalidation will be enabled to support x2apic and Intr-remapping.\n");
 
 		eim = !dmar_x2apic_optout();
@@ -678,9 +713,6 @@ static int __init intel_enable_irq_remapping(void)
 		if (!ecap_ir_support(iommu->ecap))
 			continue;
 
-		if (intel_setup_irq_remapping(iommu))
-			goto error;
-
 		iommu_set_irq_remapping(iommu, eim);
 		setup = 1;
 	}
@@ -702,15 +734,7 @@ static int __init intel_enable_irq_remapping(void)
 	return eim ? IRQ_REMAP_X2APIC_MODE : IRQ_REMAP_XAPIC_MODE;
 
 error:
-	for_each_iommu(iommu, drhd)
-		if (ecap_ir_support(iommu->ecap)) {
-			iommu_disable_irq_remapping(iommu);
-			intel_teardown_irq_remapping(iommu);
-		}
-
-	if (x2apic_present)
-		pr_warn("Failed to enable irq remapping.  You are vulnerable to irq-injection attacks.\n");
-
+	intel_cleanup_irq_remapping();
 	return -1;
 }
 
@@ -1200,7 +1224,7 @@ static int intel_alloc_hpet_msi(unsigned int irq, unsigned int id)
 
 struct irq_remap_ops intel_irq_remap_ops = {
 	.supported		= intel_irq_remapping_supported,
-	.prepare		= dmar_table_init,
+	.prepare		= intel_prepare_irq_remapping,
 	.enable			= intel_enable_irq_remapping,
 	.disable		= disable_irq_remapping,
 	.reenable		= reenable_irq_remapping,
-- 
1.7.10.4

[Patch v1 04/17] iommu/vt-d: Convert allocations to GFP_KERNEL

[Jiang Liu]

From: Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>

No reason anymore to do GFP_ATOMIC allocations which are not harmful
in the normal bootup case, but matter in the physical hotplug
scenario.

Signed-off-by: Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
Tested-by: Borislav Petkov <bp-Gina5bIWoIWzQB+pC5nmwQ@public.gmane.org>
Acked-by: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
Cc: Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Cc: x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org
Link: http://lkml.kernel.org/r/20141205084147.472428339-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org
Signed-off-by: Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
Signed-off-by: Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 drivers/iommu/intel_irq_remapping.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
index 4b80e16e0736..d5b7a096c240 100644
--- a/drivers/iommu/intel_irq_remapping.c
+++ b/drivers/iommu/intel_irq_remapping.c
@@ -481,11 +481,11 @@ static int intel_setup_irq_remapping(struct intel_iommu *iommu)
 	if (iommu->ir_table)
 		return 0;
 
-	ir_table = kzalloc(sizeof(struct ir_table), GFP_ATOMIC);
+	ir_table = kzalloc(sizeof(struct ir_table), GFP_KERNEL);
 	if (!ir_table)
 		return -ENOMEM;
 
-	pages = alloc_pages_node(iommu->node, GFP_ATOMIC | __GFP_ZERO,
+	pages = alloc_pages_node(iommu->node, GFP_KERNEL | __GFP_ZERO,
 				 INTR_REMAP_PAGE_ORDER);
 
 	if (!pages) {
-- 
1.7.10.4

[Patch v1 05/17] x86/apic: Panic if kernel doesn't support x2apic but BIOS has enabled x2apic

[Jiang Liu]

When kernel doesn't support X2APIC but BIOS has enabled X2APIC, system
may panic or hang without useful messages. On the other hand, it's
hard to dynamically disable X2APIC when CONFIG_X86_X2APIC is disabled.
So panic with a clear message in such a case.

System panics as below when X2APIC is disabled and interrupt remapping
is enabled:
[    0.316118] LAPIC pending interrupts after 512 EOI
[    0.322126] ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
[    0.368655] Kernel panic - not syncing: timer doesn't work through Interrupt-remapped IO-APIC
[    0.378300] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.18.0+ #340
[    0.385300] Hardware name: Intel Corporation BRICKLAND/BRICKLAND, BIOS BRIVTIN1.86B.0051.L05.1406240953 06/24/2014
[    0.396997]  ffff88046dc03000 ffff88046c307dd8 ffffffff8179dada 00000000000043f2
[    0.405629]  ffffffff81a92158 ffff88046c307e58 ffffffff8179b757 0000000000000002
[    0.414261]  0000000000000008 ffff88046c307e68 ffff88046c307e08 ffffffff813ad82b
[    0.422890] Call Trace:
[    0.425711]  [<ffffffff8179dada>] dump_stack+0x45/0x57
[    0.431533]  [<ffffffff8179b757>] panic+0xc1/0x1f5
[    0.436978]  [<ffffffff813ad82b>] ? delay_tsc+0x3b/0x70
[    0.442910]  [<ffffffff8166fa2c>] panic_if_irq_remap+0x1c/0x20
[    0.449524]  [<ffffffff81d73645>] setup_IO_APIC+0x405/0x82e
[    0.464979]  [<ffffffff81d6fcc2>] native_smp_prepare_cpus+0x2d9/0x31c
[    0.472274]  [<ffffffff81d5d0ac>] kernel_init_freeable+0xd6/0x223
[    0.479170]  [<ffffffff81792ad0>] ? rest_init+0x80/0x80
[    0.485099]  [<ffffffff81792ade>] kernel_init+0xe/0xf0
[    0.490932]  [<ffffffff817a537c>] ret_from_fork+0x7c/0xb0
[    0.497054]  [<ffffffff81792ad0>] ? rest_init+0x80/0x80
[    0.502983] ---[ end Kernel panic - not syncing: timer doesn't work through Interrupt-remapped IO-APIC

System hangs as below when X2APIC and interrupt remapping are both disabled:
[    1.102782] pci 0000:00:02.0: System wakeup disabled by ACPI
[    1.109351] pci 0000:00:03.0: System wakeup disabled by ACPI
[    1.115915] pci 0000:00:03.2: System wakeup disabled by ACPI
[    1.122479] pci 0000:00:03.3: System wakeup disabled by ACPI
[    1.132274] pci 0000:00:1c.0: Enabling MPC IRBNCE
[    1.137620] pci 0000:00:1c.0: Intel PCH root port ACS workaround enabled
[    1.145239] pci 0000:00:1c.0: System wakeup disabled by ACPI
[    1.151790] pci 0000:00:1c.7: Enabling MPC IRBNCE
[    1.157128] pci 0000:00:1c.7: Intel PCH root port ACS workaround enabled
[    1.164748] pci 0000:00:1c.7: System wakeup disabled by ACPI
[    1.171447] pci 0000:00:1e.0: System wakeup disabled by ACPI
[    1.178612] acpiphp: Slot [8] registered
[    1.183095] pci 0000:00:02.0: PCI bridge to [bus 01]
[    1.188867] acpiphp: Slot [2] registered

Signed-off-by: Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 arch/x86/kernel/apic/apic.c |    8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 5fd533a4c7a5..9c43899433e3 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1597,6 +1597,14 @@ void __init enable_IR_x2apic(void)
 	int ret, x2apic_enabled = 0;
 	int hardware_init_ret;
 
+	if (!IS_ENABLED(CONFIG_X86_X2APIC)) {
+		u64 msr;
+
+		rdmsrl(MSR_IA32_APICBASE, msr);
+		if (msr & X2APIC_ENABLE)
+			panic("BIOS has enabled x2apic but kernel doesn't support x2apic, please disable x2apic in BIOS.\n");
+	}
+
 	hardware_init_ret = irq_remapping_prepare();
 	if (hardware_init_ret && !x2apic_supported())
 		return;
-- 
1.7.10.4

[Patch v1 06/17] x86/apic: Kill useless variable x2apic_enabled in function enable_IR_x2apic()

[Jiang Liu]

Local variable x2apic_enabled has been assigned to but never referred,
so kill it.

Signed-off-by: Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 arch/x86/kernel/apic/apic.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 9c43899433e3..4a65e1aced33 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1594,7 +1594,7 @@ int __init enable_IR(void)
 void __init enable_IR_x2apic(void)
 {
 	unsigned long flags;
-	int ret, x2apic_enabled = 0;
+	int ret;
 	int hardware_init_ret;
 
 	if (!IS_ENABLED(CONFIG_X86_X2APIC)) {
@@ -1652,8 +1652,6 @@ void __init enable_IR_x2apic(void)
 		goto skip_x2apic;
 	}
 
-	x2apic_enabled = 1;
-
 	if (x2apic_supported() && !x2apic_mode) {
 		x2apic_mode = 1;
 		enable_x2apic();
-- 
1.7.10.4

[Patch v1 07/17] x86/apic: Correctly detect X2APIC status in function enable_IR()

[Jiang Liu]

X2APIC will be disabled if user specifies "nox2apic" on kernel command
line, even when x2apic_preenabled is true. So correctly detect X2APIC
status by using x2apic_enabled() instead of x2apic_preenabled.

Signed-off-by: Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 arch/x86/kernel/apic/apic.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 4a65e1aced33..ab7c7f9eb85f 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1580,7 +1580,7 @@ int __init enable_IR(void)
 		return -1;
 	}
 
-	if (!x2apic_preenabled && skip_ioapic_setup) {
+	if (!x2apic_enabled() && skip_ioapic_setup) {
 		pr_info("Skipped enabling intr-remap because of skipping "
 			"io-apic setup\n");
 		return -1;
-- 
1.7.10.4

[Patch v1 08/17] x86/apic: Refine enable_IR_x2apic() and related functions

[Jiang Liu]

Refine enable_IR_x2apic() and related functions for better readability.

It also changes the way to handle IR in XAPIC mode when enabling X2APIC.
Previously it just skips X2APIC initialization without checking max CPU
APIC ID in system, which may cause problem if system has CPU with APIC
ID bigger than 255. So treat IR in XAPIC mode as same as IR is disabled
when enabling CPU X2APIC.

Signed-off-by: Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 arch/x86/kernel/apic/apic.c |   85 +++++++++++++++++++++----------------------
 1 file changed, 41 insertions(+), 44 deletions(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index ab7c7f9eb85f..c6204eab3d1b 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1572,7 +1572,7 @@ void enable_x2apic(void)
 }
 #endif /* CONFIG_X86_X2APIC */
 
-int __init enable_IR(void)
+static int __init try_to_enable_IR(void)
 {
 #ifdef CONFIG_IRQ_REMAP
 	if (!irq_remapping_supported()) {
@@ -1585,17 +1585,48 @@ int __init enable_IR(void)
 			"io-apic setup\n");
 		return -1;
 	}
+#endif
 
 	return irq_remapping_enable();
+}
+
+static __init void try_to_enable_x2apic(int ir_stat)
+{
+#ifdef CONFIG_X86_X2APIC
+	if (!x2apic_supported())
+		return;
+
+	if (ir_stat != IRQ_REMAP_X2APIC_MODE) {
+		/* IR is required if there is APIC ID > 255 even when running
+		 * under KVM
+		 */
+		if (max_physical_apicid > 255 ||
+		    !hypervisor_x2apic_available()) {
+			pr_info("IRQ remapping doesn't support X2APIC mode, disable x2apic.\n");
+			if (x2apic_preenabled)
+				disable_x2apic();
+			return;
+		}
+
+		/*
+		 * without IR all CPUs can be addressed by IOAPIC/MSI
+		 * only in physical mode
+		 */
+		x2apic_force_phys();
+	}
+
+	if (!x2apic_mode) {
+		x2apic_mode = 1;
+		enable_x2apic();
+		pr_info("Enabled x2apic\n");
+	}
 #endif
-	return -1;
 }
 
 void __init enable_IR_x2apic(void)
 {
 	unsigned long flags;
-	int ret;
-	int hardware_init_ret;
+	int ret, ir_stat;
 
 	if (!IS_ENABLED(CONFIG_X86_X2APIC)) {
 		u64 msr;
@@ -1605,8 +1636,8 @@ void __init enable_IR_x2apic(void)
 			panic("BIOS has enabled x2apic but kernel doesn't support x2apic, please disable x2apic in BIOS.\n");
 	}
 
-	hardware_init_ret = irq_remapping_prepare();
-	if (hardware_init_ret && !x2apic_supported())
+	ir_stat = irq_remapping_prepare();
+	if (ir_stat < 0 && !x2apic_supported())
 		return;
 
 	ret = save_ioapic_entries();
@@ -1621,45 +1652,11 @@ void __init enable_IR_x2apic(void)
 
 	if (x2apic_preenabled && nox2apic)
 		disable_x2apic();
+	if (ir_stat >= 0)
+		ir_stat = try_to_enable_IR();
+	try_to_enable_x2apic(ir_stat);
 
-	if (hardware_init_ret)
-		ret = -1;
-	else
-		ret = enable_IR();
-
-	if (!x2apic_supported())
-		goto skip_x2apic;
-
-	if (ret < 0) {
-		/* IR is required if there is APIC ID > 255 even when running
-		 * under KVM
-		 */
-		if (max_physical_apicid > 255 ||
-		    !hypervisor_x2apic_available()) {
-			if (x2apic_preenabled)
-				disable_x2apic();
-			goto skip_x2apic;
-		}
-		/*
-		 * without IR all CPUs can be addressed by IOAPIC/MSI
-		 * only in physical mode
-		 */
-		x2apic_force_phys();
-	}
-
-	if (ret == IRQ_REMAP_XAPIC_MODE) {
-		pr_info("x2apic not enabled, IRQ remapping is in xapic mode\n");
-		goto skip_x2apic;
-	}
-
-	if (x2apic_supported() && !x2apic_mode) {
-		x2apic_mode = 1;
-		enable_x2apic();
-		pr_info("Enabled x2apic\n");
-	}
-
-skip_x2apic:
-	if (ret < 0) /* IR enabling failed */
+	if (ir_stat < 0) /* IR enabling failed */
 		restore_ioapic_entries();
 	legacy_pic->restore_mask();
 	local_irq_restore(flags);
-- 
1.7.10.4

[Patch v1 09/17] iommu/vt-d: Prepare for killing function irq_remapping_supported()

[Jiang Liu]

Prepare for killing function irq_remapping_supported() by moving code
from intel_irq_remapping_supported() into intel_prepare_irq_remapping().

Combined with patch from Joerg at https://lkml.org/lkml/2014/12/15/487,
so assume an signed-off from Joerg.

Signed-off-by: Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Signed-off-by: Joerg Roedel <jroedel-l3A5Bk7waGM@public.gmane.org>
---
 drivers/iommu/intel_irq_remapping.c |   58 +++++++++++++++--------------------
 1 file changed, 25 insertions(+), 33 deletions(-)

diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
index d5b7a096c240..b7ce4f458b29 100644
--- a/drivers/iommu/intel_irq_remapping.c
+++ b/drivers/iommu/intel_irq_remapping.c
@@ -568,30 +568,6 @@ static int __init dmar_x2apic_optout(void)
 
 static int __init intel_irq_remapping_supported(void)
 {
-	struct dmar_drhd_unit *drhd;
-	struct intel_iommu *iommu;
-
-	if (disable_irq_remap)
-		return 0;
-	if (irq_remap_broken) {
-		printk(KERN_WARNING
-			"This system BIOS has enabled interrupt remapping\n"
-			"on a chipset that contains an erratum making that\n"
-			"feature unstable.  To maintain system stability\n"
-			"interrupt remapping is being disabled.  Please\n"
-			"contact your BIOS vendor for an update\n");
-		add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK);
-		disable_irq_remap = 1;
-		return 0;
-	}
-
-	if (!dmar_ir_support())
-		return 0;
-
-	for_each_iommu(iommu, drhd)
-		if (!ecap_ir_support(iommu->ecap))
-			return 0;
-
 	return 1;
 }
 
@@ -616,26 +592,42 @@ static int __init intel_prepare_irq_remapping(void)
 	struct dmar_drhd_unit *drhd;
 	struct intel_iommu *iommu;
 
+	/* First check whether IRQ remapping should be enabled */
+	if (disable_irq_remap)
+		return -ENODEV;
+
+	if (irq_remap_broken) {
+		printk(KERN_WARNING
+			"This system BIOS has enabled interrupt remapping\n"
+			"on a chipset that contains an erratum making that\n"
+			"feature unstable.  To maintain system stability\n"
+			"interrupt remapping is being disabled.  Please\n"
+			"contact your BIOS vendor for an update\n");
+		add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK);
+		disable_irq_remap = 1;
+		return -ENODEV;
+	}
+
 	if (dmar_table_init() < 0)
-		return -1;
+		return -ENODEV;
+
+	if (!dmar_ir_support())
+		return -ENODEV;
 
 	if (parse_ioapics_under_ir() != 1) {
 		printk(KERN_INFO "Not enabling interrupt remapping\n");
 		goto error;
 	}
 
-	for_each_iommu(iommu, drhd) {
-		if (!ecap_ir_support(iommu->ecap))
-			continue;
-
-		/* Do the allocations early */
-		if (intel_setup_irq_remapping(iommu))
+	for_each_iommu(iommu, drhd)
+		if (!ecap_ir_support(iommu->ecap) ||
+		    intel_setup_irq_remapping(iommu))
 			goto error;
-	}
 	return 0;
+
 error:
 	intel_cleanup_irq_remapping();
-	return -1;
+	return -ENODEV;
 }
 
 static int __init intel_enable_irq_remapping(void)
-- 
1.7.10.4

[Patch v1 10/17] iommu/vt-d: Allocate IRQ remapping data structures only for all IOMMUs

[Jiang Liu]

From: Joerg Roedel <jroedel-l3A5Bk7waGM@public.gmane.org>

IRQ remapping is only supported when all IOMMUs in the
system support it. So check if all IOMMUs in the system
support IRQ remapping before doing the allocations.

[Jiang]
1) Rebased onto v3.19.
2) Remove redundant check of ecap_ir_support(iommu->ecap) in function
   intel_enable_irq_remapping().

Signed-off-by: Joerg Roedel <jroedel-l3A5Bk7waGM@public.gmane.org>
Signed-off-by: Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 drivers/iommu/intel_irq_remapping.c |   19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
index b7ce4f458b29..a47cb31f198e 100644
--- a/drivers/iommu/intel_irq_remapping.c
+++ b/drivers/iommu/intel_irq_remapping.c
@@ -619,10 +619,16 @@ static int __init intel_prepare_irq_remapping(void)
 		goto error;
 	}
 
+	/* First make sure all IOMMUs support IRQ remapping */
 	for_each_iommu(iommu, drhd)
-		if (!ecap_ir_support(iommu->ecap) ||
-		    intel_setup_irq_remapping(iommu))
+		if (!ecap_ir_support(iommu->ecap))
+			goto error;
+
+	/* Do the allocations early */
+	for_each_iommu(iommu, drhd)
+		if (intel_setup_irq_remapping(iommu))
 			goto error;
+
 	return 0;
 
 error:
@@ -673,16 +679,12 @@ static int __init intel_enable_irq_remapping(void)
 	/*
 	 * check for the Interrupt-remapping support
 	 */
-	for_each_iommu(iommu, drhd) {
-		if (!ecap_ir_support(iommu->ecap))
-			continue;
-
+	for_each_iommu(iommu, drhd)
 		if (eim && !ecap_eim_support(iommu->ecap)) {
 			printk(KERN_INFO "DRHD %Lx: EIM not supported by DRHD, "
 			       " ecap %Lx\n", drhd->reg_base_addr, iommu->ecap);
 			goto error;
 		}
-	}
 
 	/*
 	 * Enable queued invalidation for all the DRHD's.
@@ -702,9 +704,6 @@ static int __init intel_enable_irq_remapping(void)
 	 * Setup Interrupt-remapping for all the DRHD's now.
 	 */
 	for_each_iommu(iommu, drhd) {
-		if (!ecap_ir_support(iommu->ecap))
-			continue;
-
 		iommu_set_irq_remapping(iommu, eim);
 		setup = 1;
 	}
-- 
1.7.10.4

[Patch v1 11/17] iommu/vt-d: Allow IR works in XAPIC mode though CPU works in X2APIC mode

[Jiang Liu]

Currently if CPU supports X2APIC, IR hardware must work in X2APIC mode
or disabled. Change the code to support IR working in XAPIC mode when
CPU supports X2APIC. Then the CPU APIC driver will decide how to handle
such as configuration by:
1) Disabling X2APIC mode
2) Forcing X2APIC physical mode

This change also fixes a live locking when
1) BIOS enables CPU X2APIC
2) DMAR table disables X2APIC mode or IR hardware doesn't support X2APIC
with following messages:
[   37.863463] dmar: INTR-REMAP: Request device [[f0:1f.7] fault index 2
[   37.863463] INTR-REMAP:[fault reason 36] Detected reserved fields in the IRTE entry
[   37.879372] dmar: INTR-REMAP: Request device [[f0:1f.7] fault index 2
[   37.879372] INTR-REMAP:[fault reason 36] Detected reserved fields in the IRTE entry
[   37.895282] dmar: INTR-REMAP: Request device [[f0:1f.7] fault index 2
[   37.895282] INTR-REMAP:[fault reason 36] Detected reserved fields in the IRTE entry
[   37.911192] dmar: INTR-REMAP: Request device [[f0:1f.7] fault index 2

Signed-off-by: Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 drivers/iommu/intel_irq_remapping.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
index a47cb31f198e..caf803ab1abc 100644
--- a/drivers/iommu/intel_irq_remapping.c
+++ b/drivers/iommu/intel_irq_remapping.c
@@ -32,8 +32,9 @@ struct hpet_scope {
 };
 
 #define IR_X2APIC_MODE(mode) (mode ? (1 << 11) : 0)
-#define IRTE_DEST(dest) ((x2apic_mode) ? dest : dest << 8)
+#define IRTE_DEST(dest) ((eim_mode) ? dest : dest << 8)
 
+static int __read_mostly eim_mode;
 static struct ioapic_scope ir_ioapic[MAX_IO_APICS];
 static struct hpet_scope ir_hpet[MAX_HPET_TBS];
 
@@ -644,8 +645,6 @@ static int __init intel_enable_irq_remapping(void)
 	int eim = 0;
 
 	if (x2apic_supported()) {
-		pr_info("Queued invalidation will be enabled to support x2apic and Intr-remapping.\n");
-
 		eim = !dmar_x2apic_optout();
 		if (!eim)
 			printk(KERN_WARNING
@@ -683,8 +682,11 @@ static int __init intel_enable_irq_remapping(void)
 		if (eim && !ecap_eim_support(iommu->ecap)) {
 			printk(KERN_INFO "DRHD %Lx: EIM not supported by DRHD, "
 			       " ecap %Lx\n", drhd->reg_base_addr, iommu->ecap);
-			goto error;
+			eim = 0;
 		}
+	eim_mode = eim;
+	if (eim)
+		pr_info("Queued invalidation will be enabled to support x2apic and Intr-remapping.\n");
 
 	/*
 	 * Enable queued invalidation for all the DRHD's.
-- 
1.7.10.4

[Patch v1 12/17] x86/apic: Only disable CPU x2apic mode when necessary

[Jiang Liu]

When interrupt remapping hardware is not in X2APIC, CPU X2APIC mode
will be disabled if:
1) Maximum CPU APIC ID is bigger than 255
2) hypervisior doesn't support x2apic mode.

But we should only check whether hypervisor supports X2APIC mode when
hypervisor(CONFIG_HYPERVISOR_GUEST) is enabled, otherwise X2APIC will
always be disabled when CONFIG_HYPERVISOR_GUEST is disabled and IR
doesn't work in X2APIC mode.

Signed-off-by: Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 arch/x86/kernel/apic/apic.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index c6204eab3d1b..95ed9e7e7548 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1601,7 +1601,8 @@ static __init void try_to_enable_x2apic(int ir_stat)
 		 * under KVM
 		 */
 		if (max_physical_apicid > 255 ||
-		    !hypervisor_x2apic_available()) {
+		    (IS_ENABLED(CONFIG_HYPERVISOR_GUEST) &&
+		     !hypervisor_x2apic_available())) {
 			pr_info("IRQ remapping doesn't support X2APIC mode, disable x2apic.\n");
 			if (x2apic_preenabled)
 				disable_x2apic();
-- 
1.7.10.4

[Patch v1 13/17] iommu/amd: Check for irq-remap support amd_iommu_prepare()

[Jiang Liu]

From: Joerg Roedel <jroedel-l3A5Bk7waGM@public.gmane.org>

This allows to get rid of the irq_remapping_supported()
function and all its call-backs into the Intel and AMD
IOMMU drivers.

Signed-off-by: Joerg Roedel <jroedel-l3A5Bk7waGM@public.gmane.org>
Signed-off-by: Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 drivers/iommu/amd_iommu_init.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index b0522f15730f..0039f87f48b8 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -2123,6 +2123,9 @@ static int __init iommu_go_to_state(enum iommu_init_state state)
 #ifdef CONFIG_IRQ_REMAP
 int __init amd_iommu_prepare(void)
 {
+	if (!amd_iommu_irq_remap)
+		return -1;
+
 	return iommu_go_to_state(IOMMU_ACPI_FINISHED);
 }
 
-- 
1.7.10.4

[Patch v1 14/17] iommu/irq_remapping: Kill function irq_remapping_supported() and related code

[Jiang Liu]

Simplify irq_remapping code by killing irq_remapping_supported() and
related interfaces.

Joerg posted a similar patch at https://lkml.org/lkml/2014/12/15/490,
so assume an signed-off from Joerg.

Signed-off-by: Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Signed-off-by: Joerg Roedel <jroedel-l3A5Bk7waGM@public.gmane.org>
---
 arch/x86/include/asm/irq_remapping.h |    2 --
 arch/x86/kernel/apic/apic.c          |    7 +------
 drivers/iommu/amd_iommu.c            |    1 -
 drivers/iommu/amd_iommu_init.c       |    5 -----
 drivers/iommu/amd_iommu_proto.h      |    1 -
 drivers/iommu/intel_irq_remapping.c  |    6 ------
 drivers/iommu/irq_remapping.c        |   12 ++----------
 drivers/iommu/irq_remapping.h        |    3 ---
 8 files changed, 3 insertions(+), 34 deletions(-)

diff --git a/arch/x86/include/asm/irq_remapping.h b/arch/x86/include/asm/irq_remapping.h
index f1b619e5a50d..6224d316c405 100644
--- a/arch/x86/include/asm/irq_remapping.h
+++ b/arch/x86/include/asm/irq_remapping.h
@@ -33,7 +33,6 @@ struct irq_cfg;
 
 #ifdef CONFIG_IRQ_REMAP
 
-extern int irq_remapping_supported(void);
 extern void set_irq_remapping_broken(void);
 extern int irq_remapping_prepare(void);
 extern int irq_remapping_enable(void);
@@ -59,7 +58,6 @@ void irq_remap_modify_chip_defaults(struct irq_chip *chip);
 
 #else  /* CONFIG_IRQ_REMAP */
 
-static inline int irq_remapping_supported(void) { return 0; }
 static inline void set_irq_remapping_broken(void) { }
 static inline int irq_remapping_prepare(void) { return -ENODEV; }
 static inline int irq_remapping_enable(void) { return -ENODEV; }
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 95ed9e7e7548..330e69d908df 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1574,12 +1574,7 @@ void enable_x2apic(void)
 
 static int __init try_to_enable_IR(void)
 {
-#ifdef CONFIG_IRQ_REMAP
-	if (!irq_remapping_supported()) {
-		pr_debug("intr-remapping not supported\n");
-		return -1;
-	}
-
+#ifdef CONFIG_X86_IO_APIC
 	if (!x2apic_enabled() && skip_ioapic_setup) {
 		pr_info("Skipped enabling intr-remap because of skipping "
 			"io-apic setup\n");
diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index b205f76d7129..440152380446 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -4284,7 +4284,6 @@ static int alloc_hpet_msi(unsigned int irq, unsigned int id)
 }
 
 struct irq_remap_ops amd_iommu_irq_ops = {
-	.supported		= amd_iommu_supported,
 	.prepare		= amd_iommu_prepare,
 	.enable			= amd_iommu_enable,
 	.disable		= amd_iommu_disable,
diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index 0039f87f48b8..970979ecbebb 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -2129,11 +2129,6 @@ int __init amd_iommu_prepare(void)
 	return iommu_go_to_state(IOMMU_ACPI_FINISHED);
 }
 
-int __init amd_iommu_supported(void)
-{
-	return amd_iommu_irq_remap ? 1 : 0;
-}
-
 int __init amd_iommu_enable(void)
 {
 	int ret;
diff --git a/drivers/iommu/amd_iommu_proto.h b/drivers/iommu/amd_iommu_proto.h
index 95ed6deae47f..861af9d8338a 100644
--- a/drivers/iommu/amd_iommu_proto.h
+++ b/drivers/iommu/amd_iommu_proto.h
@@ -33,7 +33,6 @@ extern void amd_iommu_init_notifier(void);
 extern void amd_iommu_init_api(void);
 
 /* Needed for interrupt remapping */
-extern int amd_iommu_supported(void);
 extern int amd_iommu_prepare(void);
 extern int amd_iommu_enable(void);
 extern void amd_iommu_disable(void);
diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
index caf803ab1abc..9c1aafb26632 100644
--- a/drivers/iommu/intel_irq_remapping.c
+++ b/drivers/iommu/intel_irq_remapping.c
@@ -567,11 +567,6 @@ static int __init dmar_x2apic_optout(void)
 	return dmar->flags & DMAR_X2APIC_OPT_OUT;
 }
 
-static int __init intel_irq_remapping_supported(void)
-{
-	return 1;
-}
-
 static void __init intel_cleanup_irq_remapping(void)
 {
 	struct dmar_drhd_unit *drhd;
@@ -1216,7 +1211,6 @@ static int intel_alloc_hpet_msi(unsigned int irq, unsigned int id)
 }
 
 struct irq_remap_ops intel_irq_remap_ops = {
-	.supported		= intel_irq_remapping_supported,
 	.prepare		= intel_prepare_irq_remapping,
 	.enable			= intel_enable_irq_remapping,
 	.disable		= disable_irq_remapping,
diff --git a/drivers/iommu/irq_remapping.c b/drivers/iommu/irq_remapping.c
index 5829131aa34a..eb944ed3a463 100644
--- a/drivers/iommu/irq_remapping.c
+++ b/drivers/iommu/irq_remapping.c
@@ -199,19 +199,11 @@ void set_irq_remapping_broken(void)
 	irq_remap_broken = 1;
 }
 
-int irq_remapping_supported(void)
+int __init irq_remapping_prepare(void)
 {
 	if (disable_irq_remap)
-		return 0;
-
-	if (!remap_ops || !remap_ops->supported)
-		return 0;
+		return -ENOSYS;
 
-	return remap_ops->supported();
-}
-
-int __init irq_remapping_prepare(void)
-{
 	remap_ops = &intel_irq_remap_ops;
 
 #ifdef CONFIG_AMD_IOMMU
diff --git a/drivers/iommu/irq_remapping.h b/drivers/iommu/irq_remapping.h
index fde250f86e60..a8edfea0ab5d 100644
--- a/drivers/iommu/irq_remapping.h
+++ b/drivers/iommu/irq_remapping.h
@@ -38,9 +38,6 @@ extern int no_x2apic_optout;
 extern int irq_remapping_enabled;
 
 struct irq_remap_ops {
-	/* Check whether Interrupt Remapping is supported */
-	int (*supported)(void);
-
 	/* Initializes hardware and makes it ready for remapping interrupts */
 	int  (*prepare)(void);
 
-- 
1.7.10.4

[Patch v1 15/17] iommu/irq_remapping: Refine function irq_remapping_prepare() for maintenance

[Jiang Liu]

Assign intel_irq_remap_ops to remap_ops only if
intel_irq_remap_ops.prepare() succeeds.

Signed-off-by: Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 drivers/iommu/irq_remapping.c |   16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/iommu/irq_remapping.c b/drivers/iommu/irq_remapping.c
index eb944ed3a463..a0b26ca853ae 100644
--- a/drivers/iommu/irq_remapping.c
+++ b/drivers/iommu/irq_remapping.c
@@ -204,15 +204,15 @@ int __init irq_remapping_prepare(void)
 	if (disable_irq_remap)
 		return -ENOSYS;
 
-	remap_ops = &intel_irq_remap_ops;
-
-#ifdef CONFIG_AMD_IOMMU
-	if (amd_iommu_irq_ops.prepare() == 0) {
+	if (intel_irq_remap_ops.prepare() == 0)
+		remap_ops = &intel_irq_remap_ops;
+	else if (IS_ENABLED(CONFIG_AMD_IOMMU) &&
+		 amd_iommu_irq_ops.prepare() == 0)
 		remap_ops = &amd_iommu_irq_ops;
-		return 0;
-	}
-#endif
-	return remap_ops->prepare();
+	else
+		return -ENOSYS;
+
+	return 0;
 }
 
 int __init irq_remapping_enable(void)
-- 
1.7.10.4

[Patch v1 16/17] iommu/irq_remapping: Change variable disable_irq_remap to be static

[Jiang Liu]

Change variable disable_irq_remap to be static and simplify the code.

Signed-off-by: Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 drivers/iommu/amd_iommu_init.c      |    6 +-----
 drivers/iommu/intel_irq_remapping.c |    5 -----
 drivers/iommu/irq_remapping.c       |    3 +--
 drivers/iommu/irq_remapping.h       |    2 --
 4 files changed, 2 insertions(+), 14 deletions(-)

diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index 970979ecbebb..e430dc8dffdf 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -2014,9 +2014,6 @@ static bool detect_ivrs(void)
 	/* Make sure ACS will be enabled during PCI probe */
 	pci_request_acs();
 
-	if (!disable_irq_remap)
-		amd_iommu_irq_remap = true;
-
 	return true;
 }
 
@@ -2123,8 +2120,7 @@ static int __init iommu_go_to_state(enum iommu_init_state state)
 #ifdef CONFIG_IRQ_REMAP
 int __init amd_iommu_prepare(void)
 {
-	if (!amd_iommu_irq_remap)
-		return -1;
+	amd_iommu_irq_remap = true;
 
 	return iommu_go_to_state(IOMMU_ACPI_FINISHED);
 }
diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
index 9c1aafb26632..78cdd0d15424 100644
--- a/drivers/iommu/intel_irq_remapping.c
+++ b/drivers/iommu/intel_irq_remapping.c
@@ -588,10 +588,6 @@ static int __init intel_prepare_irq_remapping(void)
 	struct dmar_drhd_unit *drhd;
 	struct intel_iommu *iommu;
 
-	/* First check whether IRQ remapping should be enabled */
-	if (disable_irq_remap)
-		return -ENODEV;
-
 	if (irq_remap_broken) {
 		printk(KERN_WARNING
 			"This system BIOS has enabled interrupt remapping\n"
@@ -600,7 +596,6 @@ static int __init intel_prepare_irq_remapping(void)
 			"interrupt remapping is being disabled.  Please\n"
 			"contact your BIOS vendor for an update\n");
 		add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK);
-		disable_irq_remap = 1;
 		return -ENODEV;
 	}
 
diff --git a/drivers/iommu/irq_remapping.c b/drivers/iommu/irq_remapping.c
index a0b26ca853ae..c6fdca412e71 100644
--- a/drivers/iommu/irq_remapping.c
+++ b/drivers/iommu/irq_remapping.c
@@ -17,12 +17,11 @@
 #include "irq_remapping.h"
 
 int irq_remapping_enabled;
-
-int disable_irq_remap;
 int irq_remap_broken;
 int disable_sourceid_checking;
 int no_x2apic_optout;
 
+static int disable_irq_remap;
 static struct irq_remap_ops *remap_ops;
 
 static int msi_alloc_remapped_irq(struct pci_dev *pdev, int irq, int nvec);
diff --git a/drivers/iommu/irq_remapping.h b/drivers/iommu/irq_remapping.h
index a8edfea0ab5d..c448eb48340a 100644
--- a/drivers/iommu/irq_remapping.h
+++ b/drivers/iommu/irq_remapping.h
@@ -31,7 +31,6 @@ struct cpumask;
 struct pci_dev;
 struct msi_msg;
 
-extern int disable_irq_remap;
 extern int irq_remap_broken;
 extern int disable_sourceid_checking;
 extern int no_x2apic_optout;
@@ -86,7 +85,6 @@ extern struct irq_remap_ops amd_iommu_irq_ops;
 #else  /* CONFIG_IRQ_REMAP */
 
 #define irq_remapping_enabled 0
-#define disable_irq_remap     1
 #define irq_remap_broken      0
 
 #endif /* CONFIG_IRQ_REMAP */
-- 
1.7.10.4

[Patch v1 17/17] iommu/irq_remapping: Normailize the way to detect whether IR is enabled

[Jiang Liu]

Refine code by normailizing the way to detect whether IR is enabled.

Signed-off-by: Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 drivers/iommu/irq_remapping.c |   38 ++++++++++++++------------------------
 1 file changed, 14 insertions(+), 24 deletions(-)

diff --git a/drivers/iommu/irq_remapping.c b/drivers/iommu/irq_remapping.c
index c6fdca412e71..10f4894a37e9 100644
--- a/drivers/iommu/irq_remapping.c
+++ b/drivers/iommu/irq_remapping.c
@@ -218,7 +218,7 @@ int __init irq_remapping_enable(void)
 {
 	int ret;
 
-	if (!remap_ops || !remap_ops->enable)
+	if (!remap_ops->enable)
 		return -ENODEV;
 
 	ret = remap_ops->enable();
@@ -231,22 +231,16 @@ int __init irq_remapping_enable(void)
 
 void irq_remapping_disable(void)
 {
-	if (!irq_remapping_enabled ||
-	    !remap_ops ||
-	    !remap_ops->disable)
-		return;
-
-	remap_ops->disable();
+	if (irq_remapping_enabled && remap_ops->disable)
+		remap_ops->disable();
 }
 
 int irq_remapping_reenable(int mode)
 {
-	if (!irq_remapping_enabled ||
-	    !remap_ops ||
-	    !remap_ops->reenable)
-		return 0;
+	if (irq_remapping_enabled && remap_ops->reenable)
+		return remap_ops->reenable(mode);
 
-	return remap_ops->reenable(mode);
+	return 0;
 }
 
 int __init irq_remap_enable_fault_handling(void)
@@ -254,7 +248,7 @@ int __init irq_remap_enable_fault_handling(void)
 	if (!irq_remapping_enabled)
 		return 0;
 
-	if (!remap_ops || !remap_ops->enable_faulting)
+	if (!remap_ops->enable_faulting)
 		return -ENODEV;
 
 	return remap_ops->enable_faulting();
@@ -265,7 +259,7 @@ int setup_ioapic_remapped_entry(int irq,
 				unsigned int destination, int vector,
 				struct io_apic_irq_attr *attr)
 {
-	if (!remap_ops || !remap_ops->setup_ioapic_entry)
+	if (!remap_ops->setup_ioapic_entry)
 		return -ENODEV;
 
 	return remap_ops->setup_ioapic_entry(irq, entry, destination,
@@ -275,8 +269,7 @@ int setup_ioapic_remapped_entry(int irq,
 static int set_remapped_irq_affinity(struct irq_data *data,
 				     const struct cpumask *mask, bool force)
 {
-	if (!config_enabled(CONFIG_SMP) || !remap_ops ||
-	    !remap_ops->set_affinity)
+	if (!config_enabled(CONFIG_SMP) || !remap_ops->set_affinity)
 		return 0;
 
 	return remap_ops->set_affinity(data, mask, force);
@@ -286,10 +279,7 @@ void free_remapped_irq(int irq)
 {
 	struct irq_cfg *cfg = irq_get_chip_data(irq);
 
-	if (!remap_ops || !remap_ops->free_irq)
-		return;
-
-	if (irq_remapped(cfg))
+	if (irq_remapped(cfg) && remap_ops->free_irq)
 		remap_ops->free_irq(irq);
 }
 
@@ -301,13 +291,13 @@ void compose_remapped_msi_msg(struct pci_dev *pdev,
 
 	if (!irq_remapped(cfg))
 		native_compose_msi_msg(pdev, irq, dest, msg, hpet_id);
-	else if (remap_ops && remap_ops->compose_msi_msg)
+	else if (remap_ops->compose_msi_msg)
 		remap_ops->compose_msi_msg(pdev, irq, dest, msg, hpet_id);
 }
 
 static int msi_alloc_remapped_irq(struct pci_dev *pdev, int irq, int nvec)
 {
-	if (!remap_ops || !remap_ops->msi_alloc_irq)
+	if (!remap_ops->msi_alloc_irq)
 		return -ENODEV;
 
 	return remap_ops->msi_alloc_irq(pdev, irq, nvec);
@@ -316,7 +306,7 @@ static int msi_alloc_remapped_irq(struct pci_dev *pdev, int irq, int nvec)
 static int msi_setup_remapped_irq(struct pci_dev *pdev, unsigned int irq,
 				  int index, int sub_handle)
 {
-	if (!remap_ops || !remap_ops->msi_setup_irq)
+	if (!remap_ops->msi_setup_irq)
 		return -ENODEV;
 
 	return remap_ops->msi_setup_irq(pdev, irq, index, sub_handle);
@@ -326,7 +316,7 @@ int setup_hpet_msi_remapped(unsigned int irq, unsigned int id)
 {
 	int ret;
 
-	if (!remap_ops || !remap_ops->alloc_hpet_msi)
+	if (!remap_ops->alloc_hpet_msi)
 		return -ENODEV;
 
 	ret = remap_ops->alloc_hpet_msi(irq, id);
-- 
1.7.10.4