In current code it continues setup even if alloc_msi_entry() for MSI-X
is failed due to lack of memory.  It means arch_setup_msi_irqs() might
be called with msi_desc entries less than its argument nvec.

At least x86's arch_setup_msi_irqs() uses list_for_each_entry() for
dev->msi_list that suspected to have entries same numbers as nvec, and
it doesn't check the number of allocated vectors and passed arg nvec.
Therefore it will result in success of pci_enable_msix(), with less
vectors allocated than requested.

This patch fixes the error route to return -ENOMEM, instead of continuing
the setup (proposed by Matthew Wilcox).

Note that there is no iounmap in msi_free_irqs() if no msi_disc is
allocated.
Reviewed-by: NMatthew Wilcox <matthew@wil.cx>
Signed-off-by: NHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

Use msix_mask_irq() instead of direct use of writel, so as not to clear
preserved bits in the Vector Control register [31:1].
Signed-off-by: NHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

The previous MSI-X fix (8d181018) had
three bugs.  First, it didn't move the write that disabled the vector.
This led to writing garbage to the MSI-X vector (spotted by Michael
Ellerman).  It didn't fix the PCI resume case, and it had a race window
where the device could generate an interrupt before the MSI-X registers
were programmed (leading to a DMA to random addresses).

Fortunately, the MSI-X capability has a bit to mask all the vectors.
By setting this bit instead of clearing the enable bit, we can ensure
the device will not generate spurious interrupts.  Since the capability
is now enabled, the NIU device will not have a problem with the reads
and writes to the MSI-X registers being in the original order in the code.
Signed-off-by: NMatthew Wilcox <willy@linux.intel.com>
Reviewed-by: NHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

We have the 'pos' of the MSI capability at all locations which call
msi_set_enable(), so pass it to msi_set_enable() instead of making it
find the capability every time.
Reviewed-by: NKenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: NMatthew Wilcox <willy@linux.intel.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

Remove invalid comment of msi_mask_irq().
Reviewed-by: NMatthew Wilcox <willy@linux.intel.com>
Signed-off-by: NKenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

pci_enable_msix currently returns -EINVAL if you ask
for more vectors than supported by the device, which would
typically cause fallback to regular interrupts.

It's better to return the table size, making the driver retry
MSI-X with less vectors.
Reviewed-by: NMatthew Wilcox <willy@linux.intel.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

Impact: cleanup, improve readability

Define PCI_MSI_MASK_32/64 for 32/64bit devices, instead of using
implicit offset (-4), "PCI_MSI_MASK_BIT - 4" and "PCI_MSI_MASK_BIT".
Signed-off-by: NHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Reviewed-by: NMatthew Wilcox <willy@linux.intel.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

The NIU device refuses to allow accesses to MSI-X registers before MSI-X
is enabled.  This patch fixes the problem by moving the read of the mask
register to after MSI-X is enabled.
Reported-by: NDavid S. Miller <davem@davemloft.net>
Tested-by: NDavid S. Miller <davem@davemloft.net>
Reviewed-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NMatthew Wilcox <willy@linux.intel.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

Add the new API pci_enable_msi_block() to allow drivers to
request multiple MSI and reimplement pci_enable_msi in terms of
pci_enable_msi_block.  Ensure that the architecture back ends don't
have to know about multiple MSI.
Signed-off-by: NMatthew Wilcox <willy@linux.intel.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

Since most of the callers already know whether they have an MSI or
an MSI-X capability, split msi_set_mask_bits() into msi_mask_irq()
and msix_mask_irq().  The only callers which don't (mask_msi_irq()
and unmask_msi_irq()) can share code in msi_set_mask_bit().  This then
becomes the only caller of msix_flush_writes(), so we can inline it.
The flushing read can be to any address that belongs to the device,
so we can eliminate the calculation too.

We can also get rid of maskbits_mask from struct msi_desc and simply
recalculate it on the rare occasion that we need it.  The single-bit
'masked' element is replaced by a copy of the 32-bit 'masked' register,
so this patch does not affect the size of msi_desc.
Signed-off-by: NMatthew Wilcox <willy@linux.intel.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

MSI interrupts have a mask_pos where MSI-X have a mask_base.  Use a
transparent union to get rid of some ugly casts.
Signed-off-by: NMatthew Wilcox <willy@linux.intel.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

By passing the pci_dev into alloc_msi_entry() we can be sure that
the ->dev entry is always assigned and so we don't need to check it.
Also, we used kzalloc() so we don't need to initialise ->irq to 0.
Signed-off-by: NMatthew Wilcox <willy@linux.intel.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

By changing from a 5-bit field to a 1-bit field, we free up some bits
that can be used by a later patch.  Also rearrange the fields for better
packing on 64-bit platforms (reducing the size of msi_desc from 72 bytes
to 64 bytes).
Signed-off-by: NMatthew Wilcox <willy@linux.intel.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

There is code in msix_capability_init() which, when the requested number
of MSI-X couldn't be allocated, calculates how many MSI-X /could/ be
allocated and returns that to the driver. That allows the driver to then
make a second request, with a number of MSIs that should succeed.

The current code requires the arch code to setup as many msi_descs as it
can, and then return to the generic code. On some platforms the arch
code may already know how many MSI-X it can allocate, before it sets up
any of the msi_descs.

So change the logic such that if the arch code returns a positive error
code, that is taken to be the number of MSI-X that could be allocated.
If the error code is negative we still calculate the number available
using the old method.

Because it's a little subtle, make sure the error return code from
arch_setup_msi_irq() is always negative. That way only implementations
of arch_setup_msi_irqs() need to be careful about returning a positive
error code.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

Weak functions aren't all they're cracked up to be. They lead to
incorrect binaries with some toolchains, they require us to have empty
functions we otherwise wouldn't, and the unused code is not elided
(as of gcc 4.3.2 anyway).

So replace the weak MSI arch hooks with the #define foo foo idiom. We no
longer need empty versions of arch_setup/teardown_msi_irq().

This is less source (by 1 line!), and results in smaller binaries too:

   text	   data	    bss	    dec	    hex	filename
9354300	1693916	 678424	11726640 b2ef30	build/powerpc/vmlinux-before
9354052	1693852	 678424	11726328 b2edf8	build/powerpc/vmlinux-after

Also smaller on x86_64 and arm (iop13xx).
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

Introduce new function pci_msix_table_size() returning the size of
the MSI-X table of given PCI device or 0 if the device doesn't
support MSI-X.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Reviewed-by: NHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

Hidetoshi Seto points out that commit
bffac3c5 has wrong values in the array.
Rather than correct the array, we can just use a bounds check and
perform the calculation specified in the comment.  As a bonus, this will
not run off the end of the array if the device specifies an illegal
value in the MSI capability.
Signed-off-by: NMatthew Wilcox <willy@linux.intel.com>
Signed-off-by: NHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

Add an msi_mask() function which returns the correct bitmask for the
number of MSI interrupts you have.  This fixes an undefined bug in
msi_capability_init().
Signed-off-by: NMatthew Wilcox <willy@linux.intel.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

This patch fix a following bug and does a cleanup.

bug:
	commit 5993760f
	had a wrong change (since is_64 is boolean[0|1]):

-               pci_write_config_dword(dev,
-                       msi_mask_bits_reg(pos, is_64bit_address(control)),
-                       maskbits);
+               pci_write_config_dword(dev, entry->msi_attrib.is_64, maskbits);

utilize:
	Unify separated if (entry->msi_attrib.maskbit) statements.
Signed-off-by: NHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Acked-by: N"Jike Song" <albcamus@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

The _OSC capability OSC_MSI_SUPPORT is set when the root bridge is added
with pci_acpi_osc_support(), so we no longer need to do it in the PCI
MSI driver.  Also adds the function pci_msi_enabled, which returns true
if pci=nomsi is not on the kernel command-line.
Signed-off-by: NAndrew Patterson <andrew.patterson@hp.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

Impact: simplify code

Pass irq_desc and cfg around, instead of raw IRQ numbers - this way
we dont have to look it up again and again.
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Currently linux doesn't have any code to set the "MSI supported" bit in
Support Fireld of _OSC. This patch adds the code for that.
Signed-off-by: NKenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: NTaku Izumi <izumi.taku@jp.fujitsu.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

In msi_capability_init, we can make use of the calculated results
instead of calling is_mask_bit_support and is_64bit_address twice.
Signed-off-by: NJike Song <albcamus@gmail.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

With the recent change to avoid masking MSIs using the MSI enable bit, devices
without an MSI mask bit will have their MSI capability always enabled when MSI
is in use, so we need to restore it regardless of the mask bit state.

Fixes kernel bz 11178.
Acked-by: NMatthew Wilcox <willy@linux.intel.com>
Signed-off-by: NAlan Jenkins <alan-jenkins@tuffmail.co.uk>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

David Vrabel has a device which generates an interrupt storm on the INTx
pin if we disable MSI interrupts altogether.  Masking interrupts is only
a performance optimisation, so we can ignore the request to mask the
interrupt.
Signed-off-by: NMatthew Wilcox <willy@linux.intel.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

Convert printks to use dev_printk().

I converted pr_debug() to dev_dbg().  Both use KERN_DEBUG and are enabled
only when DEBUG is defined.

I converted printk(KERN_DEBUG) to dev_printk(KERN_DEBUG), not to dev_dbg(),
because dev_dbg() is only enabled when DEBUG is defined.

I converted DBG(KERN_INFO) (only in setup-bus.c) to dev_info().  The DBG()
name makes it sound like debug, but it's been enabled forever, so dev_info()
preserves the previous behavior.

I tried to make the resource assignment formats more consistent, e.g.,
  "BAR %d: got res [%#llx-%#llx] bus [%#llx-%#llx] flags %#lx\n"
instead of sometimes using "start-end" and sometimes using "size@start".
I'm not attached to one or the other; I'd just like them consistent.
Signed-off-by: NBjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

The position of MSI capability is already cached in the msi_desc when
we enter the msi_set_mask_bits().  Use it instead.
Signed-off-by: NHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Acked-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

[PATCH 2/2] pci/irq: let pci_device_shutdown to call pci_msi_shutdown v2

this change

| commit 23a274c8
| Author: Prakash, Sathya <sathya.prakash@lsi.com>
| Date:   Fri Mar 7 15:53:21 2008 +0530
|
|     [SCSI] mpt fusion: Enable MSI by default for SAS controllers
|
|     This patch modifies the driver to enable MSI by default for all SAS chips.
|
|     Signed-off-by: Sathya Prakash <sathya.prakash@lsi.com>
|     Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
|
Causes the kexec of a RHEL 5.1 kernel to fail.

root casue: the rhel 5.1 kernel still uses INTx emulation.  and
mptscsih_shutdown doesn't call pci_disable_msi to reenable INTx on kexec path

So call pci_msi_shutdown in the shutdown path to do the same thing to msix
Signed-off-by: NYinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: NJesse Barnes <jbarnes@hobbes.lan>

[PATCH 1/2] pci/irq: restore mask_bits in msi shutdown -v3

Yinghai found that kexec'ing a RHEL 5.1 kernel with 2.6.25-rc3+ kernels
prevents his NIC from working.  He bisected to

| commit 89d694b9
| Author: Thomas Gleixner <tglx@linutronix.de>
| Date:   Mon Feb 18 18:25:17 2008 +0100
|
|   genirq: do not leave interupts enabled on free_irq
|
|   The default_disable() function was changed in commit:
|
|    76d21601
|    genirq: do not mask interrupts by default
|

For MSI, default_shutdown will call mask_bit for msi device.  All mask bits
will left disabled after free_irq.  Then in the kexec case, the next kernel
can only use msi_enable bit, so all device's MSI can not be used.

So lets to restore the mask bit to its pci reset defined value (enabled) when
we disable the kernels use of msi to be a little friendlier to kexec'd kernels.

Extend msi_set_mask_bit to msi_set_mask_bits to take mask, so we can fully
restore that to 0x00 instead of 0xfe.
Signed-off-by: NYinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: NJesse Barnes <jbarnes@hobbes.lan>

This patch fixes the following problem present with older gcc versions:

<--  snip  -->

...
  CC      drivers/pci/msi.o
/home/bunk/linux/kernel-2.6/git/linux-2.6/drivers/pci/msi.c:692: warning: weak declaration of `arch_msi_check_device' after first use results in unspecified behavior
/home/bunk/linux/kernel-2.6/git/linux-2.6/drivers/pci/msi.c:704: warning: weak declaration of `arch_setup_msi_irqs' after first use results in unspecified behavior
/home/bunk/linux/kernel-2.6/git/linux-2.6/drivers/pci/msi.c:724: warning: weak declaration of `arch_teardown_msi_irqs' after first use results in unspecified behavior
...

<--  snip  -->
Signed-off-by: NAdrian Bunk <bunk@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

PCI error recovery usually involves the PCI adapter being reset.
If the device is using MSI, the reset will cause the MSI state
to be lost; the device driver needs to restore the MSI state.

The pci_restore_msi_state() routine is currently protected
by CONFIG_PM; remove this, and also export the symbol, so
that it can be used in a modle.
Signed-off-by: NLinas Vepstas <linas@austin.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

A reasonably common problem with some devices is that they will
disable MSI generation when the INTX_DISABLE bit is set in the
PCI_COMMAND register.

Quirk this explicitly, guarding the pci_intx() calls in msi.c with
this quirk indication.

The first entries for this quirk are for 5714 and 5780 Tigon3 chips,
and thus we can remove the workaround code from the tg3.c driver.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Acked-by: NMichael Chan <mchan@broadcom.com>
Acked-by: NJeff Garzik <jgarzik@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

While reading the MSI code trying to find a reason why MSI wouldn't
work for devices that have a 32-bit MSI address capability, I noticed
that read_msi_msg() seems to read the message data from the wrong
offset in this case.
Signed-off-by: NRoland Dreier <roland@digitalvampire.org>
Acked-by: NEric W. Biederman <ebiederm@xmission.com>
Cc: stable <stable@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

With these two lines in the reverse order the drives/block/ccis.c was
oopsing in msi_free_irqs.  Silly us calling writel on an area after
we unmap it.

BUG: unable to handle kernel paging request at virtual address f8b2200c
 printing eip:
c01e9cc7
*pdpt = 0000000000003001
*pde = 0000000037e48067
*pte = 0000000000000000
Oops: 0002 [#1]
SMP
Modules linked in: cciss ipv6 parport_pc lp parport autofs4 i2c_dev i2c_core
sunrpc loop dm_multipath button battery asus_acpi ac tg3 floppy sg dm_snapshot
dm_zero dm_mirror ext3 jbd dm_mod ata_piix libata mptsas scsi_transport_sas
mptspi scsi_transport_spi mptscsih mptbase sd_mod scsi_mod
CPU:    1
EIP:    0060:[<c01e9cc7>]    Not tainted VLI
EFLAGS: 00010286   (2.6.22-rc2-gd2579053 #1)
EIP is at msi_free_irqs+0x81/0xbe
eax: f8b22000   ebx: f71f3180   ecx: f7fff280   edx: c1886eb8
esi: f7c4e800   edi: f7c4ec48   ebp: 00000002   esp: f5a0dec8
ds: 007b   es: 007b   fs: 00d8  gs: 0033  ss: 0068
Process rmmod (pid: 5286, ti=f5a0d000 task=c47d2550 task.ti=f5a0d000)
Stack: 00000002 f8b72294 00000400 f8b69ca7 f8b6bc6c 00000002 00000000 00000000
       00000000 00000000 00000000 f5a997f4 f8b69d61 f7c5a4b0 f7c4e848 f7c4e848
       f7c4e800 f7c4e800 f8b72294 f7c4e848 f8b72294 c01e3cdf f7c4e848 c024c469
Call Trace:
 [<f8b69ca7>] cciss_shutdown+0xae/0xc3 [cciss]
 [<f8b69d61>] cciss_remove_one+0xa5/0x178 [cciss]
 [<c01e3cdf>] pci_device_remove+0x16/0x35
 [<c024c469>] __device_release_driver+0x71/0x8e
 [<c024c56e>] driver_detach+0xa0/0xde
 [<c024bc5c>] bus_remove_driver+0x27/0x41
 [<c01e3ef3>] pci_unregister_driver+0xb/0x13
 [<f8b6a343>] cciss_cleanup+0xf/0x51 [cciss]
 [<c0139ced>] sys_delete_module+0x110/0x135
 [<c0104c7a>] sysenter_past_esp+0x5f/0x85

Here's a patch that just reverses the 2 lines of code as Eric suggests. Please
consider this for inclusion.
Signed-off-by: NMike Miller <mike.miller@hp.com>
Signed-off-by: NChase Maupin <chase.maupin@hp.com>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

"Mike Miller (OS Dev)" <mikem@beardog.cca.cpqcorp.net> writes:

Found what seems the problem with our vectors being listed backward.  In
drivers/pci/msi.c we should be using list_add_tail rather than list_add to
preserve the ordering across various kernels.  Please consider this for
inclusion.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Screwed-up-by: NMichael Ellerman <michael@ellerman.id.au>
Cc: "Mike Miller (OS Dev)" <mikem@beardog.cca.cpqcorp.net>
Cc: Andi Kleen <ak@suse.de>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In file included from drivers/pci/msi.c:22:
include/asm/smp.h:17:26: asm/arch/smp.h: No such file or directory
include/asm/smp.h:20:3: #error "<asm-arm/smp.h> included in non-SMP build"
include/asm/smp.h:23:1: warning: "raw_smp_processor_id" redefined
In file included from include/linux/sched.h:65,
                 from include/linux/mm.h:4,
                 from drivers/pci/msi.c:10:
include/linux/smp.h:85:1: warning: this is the location of the previous
definition

Tested on powerpc, i386, and x86_64.
Signed-off-by: NDan Williams <dan.j.williams@intel.com>
Acked-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Today's find is a triggered assertion in msi_free_irqs() when the system
doesn't support MSI, in which case arch_setup_msi_irqs() always returns
an error.

The problem is that when this happens we branch into msi_free_irqs(), to
which you added the following assertion loop:

	list_for_each_entry(entry, &dev->msi_list, list)
		BUG_ON(irq_has_action(entry->irq));

Well, if arch_setup_msi_irqs() fails, entry->irq will be zero and
although that's never assigned to any normal devices we use that IRQ
number for the timer interrupt on sparc64 so this assertion triggers.

Better to test for zero before doing the irq_has_action() assertion
thing.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Remove includes of <linux/smp_lock.h> where it is not used/needed.
Suggested by Al Viro.

Builds cleanly on x86_64, i386, alpha, ia64, powerpc, sparc,
sparc64, and arm (all 59 defconfigs).
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch introduces an optional function, arch_teardown_msi_irqs(),
which gives an arch the opportunity to do per-device teardown for
MSI/X. If that's not required, the default version simply calls
arch_teardown_msi_irq() for each msi irq required.

arch_teardown_msi_irqs() is simply passed a pdev, attached to the pdev
is a list of msi_descs, it is up to the arch to free the irq associated
with each of these as appropriate.

For archs that _don't_ implement arch_teardown_msi_irqs(), all msi_descs
with irq == 0 are considered unallocated, and the arch teardown routine
is not called on them.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This patch introduces an optional function, arch_setup_msi_irqs(),
(note the plural) which gives an arch the opportunity to do per-device
setup for MSI/X and then allocate all the requested MSI/Xs at once.

If that's not required by the arch, the default version simply calls
arch_setup_msi_irq() for each MSI irq required.

arch_setup_msi_irqs() is passed a pdev, attached to the pdev is a list
of msi_descs with irq == 0, it is up to the arch to connect these up to
an irq (via set_irq_msi()) or return an error. For convenience the number
of vectors and the type are passed also.

All msi_descs with irq != 0 are considered allocated, and the arch
teardown routine will be called on them when necessary.

The existing semantics of pci_enable_msix() are that if the requested
number of irqs can not be allocated, the maximum number that _could_ be
allocated is returned. To support that, we define that in case of an
error from arch_setup_msi_irqs(), the number of msi_descs with irq != 0
are considered allocated, and are counted toward the "max that could be
allocated".
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>