[PATCH 3.19 010/101] PCI: Dont look for ACPI hotplug parameters if ACPI is disabled

[Greg Kroah-Hartman]

3.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>

commit 8647ca9ad5a0065ad53a2ad7e39163592b6ed35e upstream.

Booting a v3.18 or newer Xen domU kernel with PCI devices passed through
results in an oops (this is a 32-bit 3.13.11 dom0 with a 64-bit 4.4.0
hypervisor and 32-bit domU):

  BUG: unable to handle kernel paging request at 0030303e
  IP: [<c06ed0e6>] acpi_ns_validate_handle+0x12/0x1a
  Call Trace:
   [<c06eda4d>] ? acpi_evaluate_object+0x31/0x1fc
   [<c06b78e1>] ? pci_get_hp_params+0x111/0x4e0
   [<c0407bc7>] ? xen_force_evtchn_callback+0x17/0x30
   [<c04085fb>] ? xen_restore_fl_direct_reloc+0x4/0x4
   [<c0699d34>] ? pci_device_add+0x24/0x450

Don't look for ACPI configuration information if ACPI has been disabled.

I don't think this is the best fix, because we can boot plain Linux (no
Xen) with "acpi=off", and we don't need this check in pci_get_hp_params().
There should be a better fix that would make Xen domU work the same way.
The domU kernel has ACPI support but it has no AML.  There should be a way
to initialize the ACPI data structures so things fail gracefully rather
than oopsing.  This is an interim fix to address the regression.

Fixes: 6cd33649fa83 ("PCI: Add pci_configure_device() during enumeration")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=96301
Reported-by: Michael D Labriola <mlabriol@xxxxxxxx>
Tested-by: Michael D Labriola <mlabriol@xxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/pci/pci-acpi.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -248,6 +248,9 @@ int pci_get_hp_params(struct pci_dev *de
 	acpi_handle handle, phandle;
 	struct pci_bus *pbus;
 
+	if (acpi_pci_disabled)
+		return -ENODEV;
+
 	handle = NULL;
 	for (pbus = dev->bus; pbus; pbus = pbus->parent) {
 		handle = acpi_pci_get_bridge_handle(pbus);


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