ACPI / sysfs: Provide quirk mechanism to prevent GPE flooding

[ Upstream commit 9c4aa1eecb48cfac18ed5e3aca9d9ae58fbafc11 ]

Sometimes, the users may require a quirk to be provided from ACPI subsystem
core to prevent a GPE from flooding.
Normally, if a GPE cannot be dispatched, ACPICA core automatically prevents
the GPE from firing. But there are cases the GPE is dispatched by _Lxx/_Exx
provided via AML table, and OSPM is lacking of the knowledge to get
_Lxx/_Exx correctly executed to handle the GPE, thus the GPE flooding may
still occur.

The existing quirk mechanism can be enabled/disabled using the following
commands to prevent such kind of GPE flooding during runtime:
 # echo mask > /sys/firmware/acpi/interrupts/gpe00
 # echo unmask > /sys/firmware/acpi/interrupts/gpe00
To avoid GPE flooding during boot, we need a boot stage mechanism.

This patch provides such a boot stage quirk mechanism to stop this kind of
GPE flooding. This patch doesn't fix any feature gap but since the new
feature gaps could be found in the future endlessly, and can disappear if
the feature gaps are filled, providing a boot parameter rather than a DMI
table should suffice.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=53071
Link: https://bugzilla.kernel.org/show_bug.cgi?id=117481
Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/887793
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 65b05ba6ef98..a6fadef92d6d 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -305,6 +305,16 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                         use by PCI
                         Format: <irq>,<irq>...
 
+        acpi_mask_gpe=  [HW,ACPI]
+                        Due to the existence of _Lxx/_Exx, some GPEs triggered
+                        by unsupported hardware/firmware features can result in
+                        GPE floodings that cannot be automatically disabled by
+                        the GPE dispatcher.
+                        This facility can be used to prevent such uncontrolled
+                        GPE floodings.
+                        Format: <int>
+                        Support masking of GPEs numbered from 0x00 to 0x7f.
+
         acpi_no_auto_serialize  [HW,ACPI]
                         Disable auto-serialization of AML methods
                         AML control methods that contain the opcodes to create