[PATCH] x86/pci: Create PCI/MSI irqdomain after x86_init.pci.arch_init()

[Thomas Gleixner <tglx@xxxxxxxxxxxxx>]

Invoking x86_init.irqs.create_pci_msi_domain() before
x86_init.pci.arch_init() breaks XEN PV.

The XEN_PV specific pci.arch_init() function overrides the default
create_pci_msi_domain() which is obviously too late.

As a consequence the XEN PV PCI/MSI allocation goes through the native
path which runs out of vectors and causes malfunction.

Invoke it after x86_init.pci.arch_init().

Fixes: 6b15ffa07dc3 ("x86/irq: Initialize PCI/MSI domain at PCI init time")
Reported-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Tested-by: Juergen Gross <jgross@xxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
 arch/x86/pci/init.c |   15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

--- a/arch/x86/pci/init.c
+++ b/arch/x86/pci/init.c
@@ -9,16 +9,23 @@
    in the right sequence from here. */
 static __init int pci_arch_init(void)
 {
-       int type;
-
-       x86_create_pci_msi_domain();
+       int type, pcbios = 1;
 
        type = pci_direct_probe();
 
        if (!(pci_probe & PCI_PROBE_NOEARLY))
                pci_mmcfg_early_init();
 
-       if (x86_init.pci.arch_init && !x86_init.pci.arch_init())
+       if (x86_init.pci.arch_init)
+               pcbios = x86_init.pci.arch_init();
+
+       /*
+        * Must happen after x86_init.pci.arch_init(). Xen sets up the
+        * x86_init.irqs.create_pci_msi_domain there.
+        */
+       x86_create_pci_msi_domain();
+
+       if (!pcbios)
                return 0;
 
        pci_pcbios_init();