This code path is only run when an MSI/MSI-X PCI device is passed
in to PV DomU.

In 2.6.37 time-frame we over-wrote the default cleanup handler for
MSI/MSI-X irq->desc to be "xen_teardown_msi_irqs". That function
calls the the xen-pcifront driver which can tell the backend to
cleanup/take back the MSI/MSI-X device.

However, we forgot to continue the process of free-ing the MSI/MSI-X
device resources (irq->desc) in the PV domU side. Which is what
the default cleanup handler: default_teardown_msi_irqs did.

Hence we would leak IRQ descriptors.

Without this patch, doing "rmmod igbvf;modprobe igbvf" multiple
times ends with abandoned IRQ descriptors:

 28:          5  xen-pirq-pcifront-msi-x
 29:          8  xen-pirq-pcifront-msi-x
...
130:         10  xen-pirq-pcifront-msi-x

with the end result of running out of IRQ descriptors.
Reviewed-by: NIan Campbell <Ian.Campbell@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Cleanup code. Cosmetic change to make the code look easier
to read.
Reviewed-by: NIan Campbell <Ian.Campbell@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

xen_allocate_pirq -> xen_map_pirq_gsi -> PHYSDEVOP_alloc_irq_vector IFF
xen_initial_domain() in addition to the kernel side book-keeping side of
things (set chip and handler, update irq_info etc) whereas
xen_allocate_pirq_msi just does the kernel book keeping.

Also xen_allocate_pirq allocates an IRQ in the 1-1 GSI space whereas
xen_allocate_pirq_msi allocates a dynamic one in the >GSI IRQ space.

All of this is uneccessary as this code path is only executed
when we run as a domU PV guest with an MSI/MSI-X PCI card passed in.
Hence we can jump straight to allocating an dynamic IRQ (and
binding it to the proper PIRQ) and skip the rest.

In short: this change is a cosmetic one.
Reviewed-by: NIan Campbell <Ian.Campbell@citrix.com>
Reviewed-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

When remapping MSIs into pirqs for PV on HVM guests, qemu is responsible
for doing the actual mapping and unmapping.
We only give qemu the desired pirq number when we ask to do the mapping
the first time, after that we should be reading back the pirq number
from qemu every time we want to re-enable the MSI.

This fixes a bug in xen_hvm_setup_msi_irqs that manifests itself when
trying to enable the same MSI for the second time: the old MSI to pirq
mapping is still valid at this point but xen_hvm_setup_msi_irqs would
try to assign a new pirq anyway.
A simple way to reproduce this bug is to assign an MSI capable network
card to a PV on HVM guest, if the user brings down the corresponding
ethernet interface and up again, Linux would fail to enable MSIs on the
device.
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>

Stanse found that xen_setup_msi_irqs leaks memory when
xen_allocate_pirq fails. Free the memory in that fail path.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: xen-devel@lists.xensource.com
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org

Add missing #include <asm/io_apic.h> to arch/x86/pci/xen.c.
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>

Implement xen_create_msi_irq to create an msi and remap it as pirq.
Use xen_create_msi_irq to implement an initial domain specific version
of setup_msi_irqs.
Signed-off-by: NQing He <qing.he@intel.com>
Signed-off-by: NYunhong Jiang <yunhong.jiang@intel.com>
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Implement xen_register_gsi to setup the correct triggering and polarity
properties of a gsi.
Implement xen_register_pirq to register a particular gsi as pirq and
receive interrupts as events.
Call xen_setup_pirqs to register all the legacy ISA irqs as pirqs.
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Map MSIs into pirqs, writing 0 in the MSI vector data field and the pirq
number in the MSI destination id field.
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Disable pcifront when running on HVM: it is meant to be used with pv
guests that don't have PCI bus.

Use acpi_register_gsi_xen_hvm to remap GSIs into pirqs.
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: NRafael J. Wysocki <rjw@sisk.pl>

xen_hvm_register_pirq allows the kernel to map a GSI into a Xen pirq and
receive the interrupt as an event channel from that point on.
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

This looks to be vestigial dependency that had never been used even
in the original code base (2.6.18) from which this driver
was up-ported. Without this fix, with the CONFIG_ISAPNP, we get this
compile failure:

arch/x86/pci/xen.c: In function 'pci_xen_init':
arch/x86/pci/xen.c:138: error: 'isapnp_disable' undeclared (first use in this function)
arch/x86/pci/xen.c:138: error: (Each undeclared identifier is reported only once
arch/x86/pci/xen.c:138: error: for each function it appears in.)
Reported-by: NLi Zefan <lizf@cn.fujitsu.com>
Tested-by: NLi Zefan <lizf@cn.fujitsu.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

The frontend stub lives in arch/x86/pci/xen.c, alongside other
sub-arch PCI init code (e.g. olpc.c).

It provides a mechanism for Xen PCI frontend to setup/destroy
legacy interrupts, MSI/MSI-X, and PCI configuration operations.

[ Impact: add core of Xen PCI support ]
[ v2: Removed the IOMMU code and only focusing on PCI.]
[ v3: removed usage of pci_scan_all_fns as that does not exist]
[ v4: introduced pci_xen value to fix compile warnings]
[ v5: squished fixes+features in one patch, changed Reviewed-by to Ccs]
[ v7: added Acked-by]
Signed-off-by: NAlex Nixon <alex.nixon@citrix.com>
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NIan Campbell <ian.campbell@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Qing He <qing.he@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org