Ever since commit 254d1a3f ("xen/pv-on-hvm kexec: shutdown watches
from old kernel") using the INTx interrupt from Xen PCI platform
device for event channel notification would just lockup the guest
during bootup.  postcore_initcall now calls xs_reset_watches which
will eventually try to read a value from XenStore and will get stuck
on read_reply at XenBus forever since the platform driver is not
probed yet and its INTx interrupt handler is not registered yet. That
means that the guest can not be notified at this moment of any pending
event channels and none of the per-event handlers will ever be invoked
(including the XenStore one) and the reply will never be picked up by
the kernel.

The exact stack where things get stuck during xenbus_init:

-xenbus_init
 -xs_init
  -xs_reset_watches
   -xenbus_scanf
    -xenbus_read
     -xs_single
      -xs_single
       -xs_talkv

Vector callbacks have always been the favourite event notification
mechanism since their introduction in commit 38e20b07 ("x86/xen:
event channels delivery on HVM.") and the vector callback feature has
always been advertised for quite some time by Xen that's why INTx was
broken for several years now without impacting anyone.

Luckily this also means that event channel notification through INTx
is basically dead-code which can be safely removed without impacting
anybody since it has been effectively disabled for more than 4 years
with nobody complaining about it (at least as far as I'm aware of).

This commit removes event channel notification through Xen PCI
platform device.

Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Julien Grall <julien.grall@citrix.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Ross Lagerwall <ross.lagerwall@citrix.com>
Cc: xen-devel@lists.xenproject.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-pci@vger.kernel.org
Cc: Anthony Liguori <aliguori@amazon.com>
Signed-off-by: NKarimAllah Ahmed <karahmed@amazon.de>
Reviewed-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>

Historically a lot of these existed because we did not have
a distinction between what was modular code and what was providing
support to modules via EXPORT_SYMBOL and friends.  That changed
when we forked out support for the latter into the export.h file.

This means we should be able to reduce the usage of module.h
in code that is obj-y Makefile or bool Kconfig.  In the case of
some of these which are modular, we can extend that to also include
files that are building basic support functionality but not related
to loading or registering the final module; such files also have
no need whatsoever for module.h

The advantage in removing such instances is that module.h itself
sources about 15 other headers; adding significantly to what we feed
cpp, and it can obscure what headers we are effectively using.

Since module.h was the source for init.h (for __init) and for
export.h (for EXPORT_SYMBOL) we consider each instance for the
presence of either and replace as needed.

In the case of crypto/glue_helper.c we delete a redundant instance
of MODULE_LICENSE in order to delete module.h -- the license info
is already present at the top of the file.

The uncore change warrants a mention too; it is uncore.c that uses
module.h and not uncore.h; hence the relocation done there.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160714001901.31603-9-paul.gortmaker@windriver.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

b4ff8389 is incomplete: relies on nr_legacy_irqs() to get the number
of legacy interrupts when actually nr_legacy_irqs() returns 0 after
probe_8259A(). Use NR_IRQS_LEGACY instead.
Signed-off-by: NStefano Stabellini <sstabellini@kernel.org>
CC: stable@vger.kernel.org

Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: iommu@lists.linux-foundation.org
Cc: linux-pm@vger.kernel.org
Cc: oprofile-list@lists.sf.net
Link: http://lkml.kernel.org/r/1459801503-15600-8-git-send-email-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

The messages should be different depending on the type of error.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>

Use accessor for_each_pci_msi_entry() to access MSI device list, so we
could easily move msi_list from struct pci_dev into struct device
later.
Signed-off-by: NJiang Liu <jiang.liu@linux.intel.com>
Acked-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: xen-devel@lists.xenproject.org
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Stuart Yoder <stuart.yoder@freescale.com>
Cc: Yijing Wang <wangyijing@huawei.com>
Cc: Borislav Petkov <bp@alien8.de>
Link: http://lkml.kernel.org/r/1436428847-8886-6-git-send-email-jiang.liu@linux.intel.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Unlike MSI, which is configured via registers in the MSI capability in
Configuration Space, MSI-X is configured via tables in Memory Space.
These MSI-X tables are mapped by a device BAR, and if no Memory Space
has been assigned to the BAR, MSI-X cannot be used.

Fail MSI-X setup if no space has been assigned for the BAR.

Previously, we ioremapped the MSI-X table even if the resource hadn't been
assigned.  In this case, the resource address is undefined (and is often
zero), which may lead to warnings or oopses in this path:

  pci_enable_msix
    msix_capability_init
      msix_map_region
        ioremap_nocache

The PCI core sets resource flags to zero when it can't assign space for the
resource (see reset_resource()).  There are also some cases where it sets
the IORESOURCE_UNSET flag, e.g., pci_reassigndev_resource_alignment(),
pci_assign_resource(), etc.  So we must check for both cases.

[bhelgaas: changelog]
Reported-by: NZhang Jukuo <zhangjukuo@huawei.com>
Tested-by: NZhang Jukuo <zhangjukuo@huawei.com>
Signed-off-by: NYijing Wang <wangyijing@huawei.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Xen overrides __acpi_register_gsi and leaves __acpi_unregister_gsi as is.
That means, an IRQ allocated by acpi_register_gsi_xen_hvm() or
acpi_register_gsi_xen() will be freed by acpi_unregister_gsi_ioapic(),
which may cause undesired effects. So override __acpi_unregister_gsi to
NULL for safety.
Signed-off-by: NJiang Liu <jiang.liu@linux.intel.com>
Tested-by: NSander Eikelenboom <linux@eikelenboom.it>
Cc: Tony Luck <tony.luck@intel.com>
Cc: xen-devel@lists.xenproject.org
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Graeme Gregory <graeme.gregory@linaro.org>
Cc: Lv Zheng <lv.zheng@intel.com>
Link: http://lkml.kernel.org/r/1421720467-7709-4-git-send-email-jiang.liu@linux.intel.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Currently Xen Domain0 has special treatment for ACPI SCI interrupt,
that is initialize irq for ACPI SCI at early stage in a special way as:
xen_init_IRQ()
	->pci_xen_initial_domain()
		->xen_setup_acpi_sci()
			Allocate and initialize irq for ACPI SCI

Function xen_setup_acpi_sci() calls acpi_gsi_to_irq() to get an irq
number for ACPI SCI. But unfortunately acpi_gsi_to_irq() depends on
IOAPIC irqdomains through following path
acpi_gsi_to_irq()
	->mp_map_gsi_to_irq()
		->mp_map_pin_to_irq()
			->check IOAPIC irqdomain

For PV domains, it uses Xen event based interrupt manangement and
doesn't make uses of native IOAPIC, so no irqdomains created for IOAPIC.
This causes Xen domain0 fail to install interrupt handler for ACPI SCI
and all ACPI events will be lost. Please refer to:
https://lkml.org/lkml/2014/12/19/178

So the fix is to get rid of special treatment for ACPI SCI, just treat
ACPI SCI as normal GSI interrupt as:
acpi_gsi_to_irq()
	->acpi_register_gsi()
		->acpi_register_gsi_xen()
			->xen_register_gsi()

With above change, there's no need for xen_setup_acpi_sci() anymore.
The above change also works with bare metal kernel too.
Signed-off-by: NJiang Liu <jiang.liu@linux.intel.com>
Tested-by: NSander Eikelenboom <linux@eikelenboom.it>
Cc: Tony Luck <tony.luck@intel.com>
Cc: xen-devel@lists.xenproject.org
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Link: http://lkml.kernel.org/r/1421720467-7709-2-git-send-email-jiang.liu@linux.intel.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

When hardware supports APIC/x2APIC virtualization we don't need to use
pirqs for MSI handling and instead use APIC since most APIC accesses
(MMIO or MSR) will now be processed without VMEXITs.

As an example, netperf on the original code produces this profile
(collected wih 'xentrace -e 0x0008ffff -T 5'):

    342 cpu_change
    260 CPUID
  34638 HLT
  64067 INJ_VIRQ
  28374 INTR
  82733 INTR_WINDOW
     10 NPF
  24337 TRAP
 370610 vlapic_accept_pic_intr
 307528 VMENTRY
 307527 VMEXIT
 140998 VMMCALL
    127 wrap_buffer

After applying this patch the same test shows

    230 cpu_change
    260 CPUID
  36542 HLT
    174 INJ_VIRQ
  27250 INTR
    222 INTR_WINDOW
     20 NPF
  24999 TRAP
 381812 vlapic_accept_pic_intr
 166480 VMENTRY
 166479 VMEXIT
  77208 VMMCALL
     81 wrap_buffer

ApacheBench results (ab -n 10000 -c 200) improve by about 10%
Signed-off-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: NAndrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>

If the hardware supports APIC virtualization we may decide not to use
pirqs and instead use APIC/x2APIC directly, meaning that we don't want
to set x86_msi.setup_msi_irqs and x86_msi.teardown_msi_irq to
Xen-specific routines.  However, x2APIC is not set up by the time
pci_xen_hvm_init() is called so we need to postpone setting these ops
until later, when we know which APIC mode is used.

(Note that currently x2APIC is never initialized on HVM guests. This
may change in the future)
Signed-off-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com>
Acked-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>

Rename write_msi_msg() to pci_write_msi_msg() to mark it as PCI
specific.
Signed-off-by: NJiang Liu <jiang.liu@linux.intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Yingjoe Chen <yingjoe.chen@mediatek.com>
Cc: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Rename __read_msi_msg() to __pci_read_msi_msg() and kill unused
read_msi_msg(). It's a preparation to separate generic MSI code from
PCI core.
Signed-off-by: NJiang Liu <jiang.liu@linux.intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Yingjoe Chen <yingjoe.chen@mediatek.com>
Cc: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

The problem fixed by 0e4ccb15 ("PCI: Add x86_msi.msi_mask_irq() and
msix_mask_irq()") has been fixed in a simpler way by a previous commit
("PCI/MSI: Add pci_msi_ignore_mask to prevent writes to MSI/MSI-X Mask
Bits").

The msi_mask_irq() and msix_mask_irq() x86_msi_ops added by 0e4ccb15
are no longer needed, so revert the commit.

default_msi_mask_irq() and default_msix_mask_irq() were added by
0e4ccb15 and are still used by s390, so keep them for now.

[bhelgaas: changelog]
Signed-off-by: NYijing Wang <wangyijing@huawei.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NDavid Vrabel <david.vrabel@citrix.com>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC: xen-devel@lists.xenproject.org

MSI-X vector Mask Bits are in MSI-X Tables in PCI memory space.  Xen PV
guests can't write to those tables.  MSI vector Mask Bits are in PCI
configuration space.  Xen PV guests can write to config space, but those
writes are ignored.

Commit 0e4ccb15 ("PCI: Add x86_msi.msi_mask_irq() and
msix_mask_irq()") added a way to override default_mask_msi_irqs() and
default_mask_msix_irqs() so they can be no-ops in Xen guests, but this is
more complicated than necessary.

Add "pci_msi_ignore_mask" in the core PCI MSI code.  If set,
default_mask_msi_irqs() and default_mask_msix_irqs() return without doing
anything.  This is less flexible, but much simpler.

[bhelgaas: changelog]
Signed-off-by: NYijing Wang <wangyijing@huawei.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NDavid Vrabel <david.vrabel@citrix.com>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC: xen-devel@lists.xenproject.org

Some platforms, such as Intel MID and mshypv, do not support legacy
interrupt controllers. So count legacy IRQs by legacy_pic->nr_legacy_irqs
instead of hard-coded NR_IRQS_LEGACY.
Signed-off-by: NJiang Liu <jiang.liu@linux.intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: xen-devel@lists.xenproject.org
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Tony Lindgren <tony@atomide.com>
Acked-by: NDavid Vrabel <david.vrabel@citrix.com>
Link: http://lkml.kernel.org/r/1402302011-23642-20-git-send-email-jiang.liu@linux.intel.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Add support for MSI message groups for Xen Dom0 using the
MAP_PIRQ_TYPE_MULTI_MSI pirq map type.

In order to keep track of which pirq is the first one in the group all
pirqs in the MSI group except for the first one have the newly
introduced PIRQ_MSI_GROUP flag set. This prevents calling
PHYSDEVOP_unmap_pirq on them, since the unmap must be done with the
first pirq in the group.
Signed-off-by: NRoger Pau Monné <roger.pau@citrix.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>

Change x86_msi.restore_msi_irqs(struct pci_dev *dev, int irq) to
x86_msi.restore_msi_irqs(struct pci_dev *dev).

restore_msi_irqs() restores multiple MSI-X IRQs, so param 'int irq' is
unneeded.  This makes code more consistent between vm and bare metal.

Dom0 MSI-X restore code can also be optimized as XEN only has a hypercall
to restore all MSI-X vectors at one time.
Tested-by: NSucheta Chakraborty <sucheta.chakraborty@qlogic.com>
Signed-off-by: NZhenzhong Duan <zhenzhong.duan@oracle.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Certain platforms do not allow writes in the MSI-X BARs to setup or tear
down vector values.  To combat against the generic code trying to write to
that and either silently being ignored or crashing due to the pagetables
being marked R/O this patch introduces a platform override.

Note that we keep two separate, non-weak, functions default_mask_msi_irqs()
and default_mask_msix_irqs() for the behavior of the arch_mask_msi_irqs()
and arch_mask_msix_irqs(), as the default behavior is needed by x86 PCI
code.

For Xen, which does not allow the guest to write to MSI-X tables - as the
hypervisor is solely responsible for setting the vector values - we
implement two nops.

This fixes a Xen guest crash when passing a PCI device with MSI-X to the
guest.  See the bugzilla for more details.

[bhelgaas: add bugzilla info]
Reference: https://bugzilla.kernel.org/show_bug.cgi?id=64581Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
CC: Sucheta Chakraborty <sucheta.chakraborty@qlogic.com>
CC: Zhenzhong Duan <zhenzhong.duan@oracle.com>

We now cache the MSI-X capability offset in the struct pci_dev, so no
need to find the capability again.
Acked-by: NJan Beulich <jbeulich@suse.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

PCI_MSIX_FLAGS_BIRMASK is mis-named because the BIR mask is in the
Table Offset register, not the flags ("Message Control" per spec)
register.
Acked-by: NJan Beulich <jbeulich@suse.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

For quite a few Xen versions, this wasn't the IRQ vector anymore
anyway, and it is not being used by the kernel for anything. Hence
drop the field from struct irq_info, and respective function
parameters.
Signed-off-by: NJan Beulich <jbeulich@suse.com>
Acked-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

There is no hypercall to setup multiple MSI per PCI device.
As such with these two new commits:
-  08261d87
   PCI/MSI: Enable multiple MSIs with pci_enable_msi_block_auto()
- 5ca72c4f
   AHCI: Support multiple MSIs

we would call the PHYSDEVOP_map_pirq 'nvec' times with the same
contents of the PCI device. Sander discovered that we would get
the same PIRQ value 'nvec' times and return said values to the
caller. That of course meant that the device was configured only
with one MSI and AHCI would fail with:

ahci 0000:00:11.0: version 3.0
xen: registering gsi 19 triggering 0 polarity 1
xen: --> pirq=19 -> irq=19 (gsi=19)
(XEN) [2013-02-27 19:43:07] IOAPIC[0]: Set PCI routing entry (6-19 -> 0x99 -> IRQ 19 Mode:1 Active:1)
ahci 0000:00:11.0: AHCI 0001.0200 32 slots 4 ports 6 Gbps 0xf impl SATA mode
ahci 0000:00:11.0: flags: 64bit ncq sntf ilck pm led clo pmp pio slum part
ahci: probe of 0000:00:11.0 failed with error -22

That is b/c in ahci_host_activate the second call to
devm_request_threaded_irq  would return -EINVAL as we passed in
(on the second run) an IRQ that was never initialized.

CC: stable@vger.kernel.org
Reported-and-Tested-by: NSander Eikelenboom <linux@eikelenboom.it>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

PV on HVM guests map GSIs into event channels. At restore time the
event channels are resumed by restore_pirqs.

Device drivers might try to register the same GSI again through ACPI at
restore time, but the GSI has already been mapped and bound by
restore_pirqs. This patch detects these situations and avoids
 mapping the same GSI multiple times.

Without this patch we get:
(XEN) irq.c:2235: dom4: pirq 23 or emuirq 28 already mapped
and waste a pirq.

CC: stable@kernel.org
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

CC: stable@kernel.org #2.6.37 and onwards
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

to make a hypercall to restore the vectors in the MSI/MSI-X
configuration space.
Signed-off-by: NTang Liang <liang.tang@oracle.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

There are three different modes: PV, HVM, and initial domain 0. In all
the cases we would return -1 for failure instead of a proper error code.
Fix this by propagating the error code from the generic IRQ code.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Now that the hypercall interface changes are in -unstable, make the
kernel side code not ignore the segment (aka domain) number anymore
(which results in pretty odd behavior on such systems). Rather, if
only the old interfaces are available, don't call them for devices on
non-zero segments at all.
Signed-off-by: NJan Beulich <jbeulich@suse.com>
[v1: Edited git description]
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

In the past we would only use the function's value if the
returned value was not equal to 'acpi_sci_override_gsi'. Meaning
that the INT_SRV_OVR values for global and source irq were different.
But it is OK to use the function's value even when the global
and source irq are the same.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

In the past (2.6.38) the 'xen_allocate_pirq_gsi' would allocate
an entry in a Linux IRQ -> {XEN_IRQ, type, event, ..} array. All
of that has been removed in 2.6.39 and the Xen IRQ subsystem uses
an linked list that is populated when the call to
'xen_allocate_irq_gsi' (universally done from any of the xen_bind_*
calls) is done. The 'xen_allocate_pirq_gsi' is a NOP and there is
no need for it anymore so lets remove it.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

As the code paths that are guarded by CONFIG_XEN_DOM0 already depend
on CONFIG_ACPI so the extra #ifdef is not required. The earlier
patch that added them in had done its job.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

.. which means we can preset of NR_IRQS_LEGACY interrupts using
the 'acpi_get_override_irq' API before this loop.
This means that we can get the IRQ's polarity (and trigger) from either
the ACPI (or MP); or use the default values. This fixes a bug if we did
not have an IOAPIC we would not been able to preset the IRQ's polarity
if the MP table existed.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Since they are only called once and the rest of the pci_xen_*
functions follow the same pattern of setup.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

.. to cut down on the code duplicity.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Not before .. also that code segment starts looking like the HVM one.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

In the past we would guard those code segments to be dependent
on CONFIG_XEN_DOM0 (which depends on CONFIG_ACPI) so this patch is
not stricly necessary. But the next patch will merge common
HVM and initial domain code and we want to make sure the CONFIG_ACPI
dependency is preserved - as HVM code does not depend on CONFIG_XEN_DOM0.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Update the out-dated comment at the beginning of the file.
Also provide the copyrights of folks who have been contributing
to this code lately.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

The file is hard to read. Move the code around so that
the contents of it follows a uniform format:
 - setup GSIs - PV, HVM, and initial domain case
 - then MSI/MSI-x setup - PV, HVM and then initial domain case.
 - then MSI/MSI-x teardown - same order.
 - lastly, the __init functions in PV, HVM, and initial domain order.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Previously we would check for acpi_sci_override_gsi == gsi every time
a PCI device was enabled. That works during early bootup, but later
on it could lead to triggering unnecessarily the acpi_gsi_to_irq(..) lookup.
The reason is that acpi_sci_override_gsi was declared in __initdata and
after early bootup could contain bogus values.

This patch moves the check for acpi_sci_override_gsi to the
site where the ACPI SCI is preset.

CC: stable@kernel.org
Reported-by: NRaghavendra D Prabhu <rprabhu@wnohang.net>
Tested-by: NRaghavendra D Prabhu <rprabhu@wnohang.net>
[http://lists.xensource.com/archives/html/xen-devel/2011-07/msg00154.html]
Suggested-by: NIan Campbell <ijc@hellion.org.uk>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

In the past we would use the GSI value to preset the ACPI SCI
IRQ which worked great as GSI == IRQ:

ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 low level)

While that is most often seen, there are some oddities:

ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 20 low level)

which means that GSI 20 (or pin 20) is to be overriden for IRQ 9.
Our code that presets the interrupt for ACPI SCI however would
use the GSI 20 instead of IRQ 9 ending up with:

xen: sci override: global_irq=20 trigger=0 polarity=1
xen: registering gsi 20 triggering 0 polarity 1
xen: --> pirq=20 -> irq=20
xen: acpi sci 20
.. snip..
calling  acpi_init+0x0/0xbc @ 1
ACPI: SCI (IRQ9) allocation failed
ACPI Exception: AE_NOT_ACQUIRED, Unable to install System Control Interrupt handler (20110413/evevent-119)
ACPI: Unable to start the ACPI Interpreter

as the ACPI interpreter made a call to 'acpi_gsi_to_irq' which got nine.
It used that value to request an IRQ (request_irq) and since that was not
present it failed.

The fix is to recognize that for interrupts that are overriden (in our
case we only care about the ACPI SCI) we should use the IRQ number
to present the IRQ instead of the using GSI. End result is that we get:

xen: sci override: global_irq=20 trigger=0 polarity=1
xen: registering gsi 20 triggering 0 polarity 1
xen: --> pirq=20 -> irq=9 (gsi=9)
xen: acpi sci 9

which fixes the ACPI interpreter failing on startup.

CC: stable@kernel.org
Reported-by: NLiwei <xieliwei@gmail.com>
Tested-by: NLiwei <xieliwei@gmail.com>
[http://lists.xensource.com/archives/html/xen-devel/2011-06/msg01727.html]
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>