While debugging an unrelated issue with the GICv3 ITS driver, the
following trace triggered:

WARNING: CPU: 1 PID: 1 at kernel/irq/irqdomain.c:1121 irq_domain_free_irqs+0x160/0x17c()
NULL pointer, cannot free irq
Modules linked in:
CPU: 1 PID: 1 Comm: swapper/0 Tainted: G        W      3.19.0-rc6+ #3690
Hardware name: FVP Base (DT)
Call trace:
[<ffffffc000089398>] dump_backtrace+0x0/0x13c
[<ffffffc0000894e4>] show_stack+0x10/0x1c
[<ffffffc00066d134>] dump_stack+0x74/0x94
[<ffffffc0000a92f8>] warn_slowpath_common+0x9c/0xd4
[<ffffffc0000a938c>] warn_slowpath_fmt+0x5c/0x80
[<ffffffc0000ee04c>] irq_domain_free_irqs+0x15c/0x17c
[<ffffffc0000ef918>] msi_domain_free_irqs+0x58/0x74
[<ffffffc000386f58>] free_msi_irqs+0xb4/0x1c0

    // The msi_prepare callback fails here

[<ffffffc0003872c0>] pci_enable_msix+0x25c/0x3d4
[<ffffffc00038746c>] pci_enable_msix_range+0x34/0x80
[<ffffffc0003924ac>] vp_try_to_find_vqs+0xec/0x528
[<ffffffc000392954>] vp_find_vqs+0x6c/0xa8
[<ffffffc0003ee2a8>] init_vq+0x120/0x248
[<ffffffc0003eefb0>] virtblk_probe+0xb0/0x6bc
[<ffffffc00038fc34>] virtio_dev_probe+0x17c/0x214
[<ffffffc0003d4a04>] driver_probe_device+0x7c/0x23c
[<ffffffc0003d4cb0>] __driver_attach+0x98/0xa0
[<ffffffc0003d2c60>] bus_for_each_dev+0x60/0xb4
[<ffffffc0003d455c>] driver_attach+0x1c/0x28
[<ffffffc0003d41b0>] bus_add_driver+0x150/0x208
[<ffffffc0003d54c0>] driver_register+0x64/0x130
[<ffffffc00038f9e8>] register_virtio_driver+0x24/0x68
[<ffffffc00091320c>] init+0x70/0xac
[<ffffffc0000828f0>] do_one_initcall+0x94/0x1d0
[<ffffffc0008e9b00>] kernel_init_freeable+0x144/0x1e4
[<ffffffc00066a434>] kernel_init+0xc/0xd8
---[ end trace f9ee562a77cc7bae ]---

The ITS msi_prepare callback having failed, we end-up trying to
free MSIs that have never been allocated. Oddly enough, the kernel
is pretty upset about it.

It turns out that this behaviour was expected before the MSI domain
was introduced (and dealt with in arch_teardown_msi_irqs).

The obvious fix is to detect this early enough and bail out.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Reviewed-by: NJiang Liu <jiang.liu@linux.intel.com>
Link: http://lkml.kernel.org/r/1422299419-6051-1-git-send-email-marc.zyngier@arm.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

No point to expose this to the world. The only legitimate user is the
core code.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>

Required to support non PCI based MSI.

[ tglx: Extracted from Jiangs patch series ]
Signed-off-by: NJiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Extend struct msi_domain_info and provide default callbacks for
msi_domain_ops.
Signed-off-by: NJiang Liu <jiang.liu@linux.intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Yijing Wang <wangyijing@huawei.com>
Cc: Yingjoe Chen <yingjoe.chen@mediatek.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Alexander Gordeev <agordeev@redhat.com>
Link: http://lkml.kernel.org/r/1416061447-9472-8-git-send-email-jiang.liu@linux.intel.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Introduce msi_domain_{alloc|free}_irqs() to alloc/free interrupts
from generic MSI irqdomain.
Signed-off-by: NJiang Liu <jiang.liu@linux.intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Yijing Wang <wangyijing@huawei.com>
Cc: Yingjoe Chen <yingjoe.chen@mediatek.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Alexander Gordeev <agordeev@redhat.com>
Link: http://lkml.kernel.org/r/1416061447-9472-7-git-send-email-jiang.liu@linux.intel.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Implement the basic functions for MSI interrupt support with
hierarchical interrupt domains.

[ tglx: Extracted and combined from several patches ]
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>