pci/hotplug/pnv-php: Disable surprise hotplug capability on conflicts

BugLink: http://bugs.launchpad.net/bugs/1667599
The root port or PCIe switch downstream port might have been associated
with driver other than pnv-php. The MSI or MSIx might also have been
enabled by that driver (e.g. pcieport_drv). Attempt to enable MSI incurs
below backtrace:

 PowerPC PowerNV PCI Hotplug Driver version: 0.1
 ------------[ cut here ]------------
 WARNING: CPU: 19 PID: 1004 at drivers/pci/msi.c:1071 \
                              __pci_enable_msi_range+0x84/0x4e0
 NIP [c000000000665c34] __pci_enable_msi_range+0x84/0x4e0
 LR [c000000000665c24] __pci_enable_msi_range+0x74/0x4e0
 Call Trace:
 [c000000384d67600] [c000000000665c24] __pci_enable_msi_range+0x74/0x4e0
 [c000000384d676e0] [d00000000aa31b04] pnv_php_register+0x564/0x5a0 [pnv_php]
 [c000000384d677c0] [d00000000aa31658] pnv_php_register+0xb8/0x5a0 [pnv_php]
 [c000000384d678a0] [d00000000aa31658] pnv_php_register+0xb8/0x5a0 [pnv_php]
 [c000000384d67980] [d00000000aa31dfc] pnv_php_init+0x60/0x98 [pnv_php]
 [c000000384d679f0] [c00000000000cfdc] do_one_initcall+0x6c/0x1d0
 [c000000384d67ab0] [c000000000b92354] do_init_module+0x94/0x254
 [c000000384d67b40] [c00000000019719c] load_module+0x258c/0x2c60
 [c000000384d67d30] [c000000000197bb0] SyS_finit_module+0xf0/0x170
 [c000000384d67e30] [c00000000000b184] system_call+0x38/0xe0

This fixes the issue by skipping enabling the surprise hotplug
capability if the MSI or MSIx on the PCI slot's upstream port has
been enabled by other driver.

Cc: <stable@vger.kernel.org> # v4.9+
Fixes: 360aebd85a4c ("drivers/pci/hotplug: Support surprise hotplug in powernv driver")
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Tested-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
(cherry picked from linux-next commit 303529d6ef1293513c2c73c9ab86489eebb37d08)
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>

diff --git a/drivers/pci/hotplug/pnv_php.c b/drivers/pci/hotplug/pnv_php.c
index 71ab158153ce15f57796065ae9b733e337e95afb..e75ec21925b1c75b60769128130fe61ab4132b6c 100644 (file)
--- a/drivers/pci/hotplug/pnv_php.c
+++ b/drivers/pci/hotplug/pnv_php.c
@@ -793,6 +793,14 @@ static void pnv_php_enable_irq(struct pnv_php_slot *php_slot)
        struct pci_dev *pdev = php_slot->pdev;
        int irq, ret;
 
+       /*
+        * The MSI/MSIx interrupt might have been occupied by other
+        * drivers. Don't populate the surprise hotplug capability
+        * in that case.
+        */
+       if (pci_dev_msi_enabled(pdev))
+               return;
+
        ret = pci_enable_device(pdev);
        if (ret) {
                dev_warn(&pdev->dev, "Error %d enabling device\n", ret);