[PATCH v2 3/3] ACPI / sysfs: Provide quirk mechanism to prevent GPE flooding

From: Lv Zheng
Date: Thu Jun 23 2016 - 02:20:39 EST


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.

This patch provides a quirk mechanism to stop this kind of GPE flooding.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=53071
Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/887793
Signed-off-by: Lv Zheng <lv.zheng@xxxxxxxxx>
---
Documentation/kernel-parameters.txt | 10 +++++++
drivers/acpi/internal.h | 1 +
drivers/acpi/scan.c | 1 +
drivers/acpi/sysfs.c | 56 +++++++++++++++++++++++++++++++++++
4 files changed, 68 insertions(+)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 82b42c9..2079b9a 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -274,6 +274,16 @@ 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 0x63.
+
acpi_no_auto_serialize [HW,ACPI]
Disable auto-serialization of AML methods
AML control methods that contain the opcodes to create
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 27cc7fe..370e184 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -37,6 +37,7 @@ void acpi_amba_init(void);
static inline void acpi_amba_init(void) {}
#endif
int acpi_sysfs_init(void);
+void acpi_gpe_apply_masked_gpes(void);
void acpi_container_init(void);
void acpi_memory_hotplug_init(void);
#ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 5f28cf7..ea70d20 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -1958,6 +1958,7 @@ int __init acpi_scan_init(void)
}
}

+ acpi_gpe_apply_masked_gpes();
acpi_update_all_gpes();

out:
diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c
index 0303c99..6fabbcf 100644
--- a/drivers/acpi/sysfs.c
+++ b/drivers/acpi/sysfs.c
@@ -704,6 +704,62 @@ end:
return result ? result : size;
}

+/*
+ * A Quirk Mechanism for GPE Flooding Prevention:
+ *
+ * Quirks may be needed to prevent GPE flooding on a specific GPE. The
+ * flooding typically cannot be detected and automatically prevented by
+ * ACPI_GPE_DISPATCH_NONE check because there is a _Lxx/_Exx prepared in
+ * the AML tables. This normally indicates a feature gap in Linux, thus
+ * instead of providing endless quirk tables, we provide a boot parameter
+ * for those who want this quirk. For example, if the users want to prevent
+ * the GPE flooding for GPE 00, they need to specify the following boot
+ * parameter:
+ * acpi_mask_gpe=0x00
+ * The masking status can be modified by the following runtime controlling
+ * interface:
+ * echo unmask > /sys/firmware/acpi/interrupts/gpe00
+ */
+
+/*
+ * Currently, the GPE flooding prevention only supports to mask the GPEs
+ * numbered from 00 to 63.
+ */
+#define ACPI_MASKABLE_GPE_MAX 64
+
+static u64 acpi_masked_gpes;
+
+static int __init acpi_gpe_set_masked_gpes(char *val)
+{
+ u8 gpe;
+
+ if (kstrtou8(val, 0, &gpe) || gpe > ACPI_MASKABLE_GPE_MAX)
+ return -EINVAL;
+ acpi_masked_gpes |= ((u64)1<<gpe);
+
+ return 1;
+}
+__setup("acpi_mask_gpe=", acpi_gpe_set_masked_gpes);
+
+void acpi_gpe_apply_masked_gpes(void)
+{
+ acpi_handle handle;
+ acpi_status status;
+ u8 gpe;
+
+ for (gpe = 0;
+ gpe < min_t(u8, ACPI_MASKABLE_GPE_MAX, acpi_current_gpe_count);
+ gpe++) {
+ if (acpi_masked_gpes & ((u64)1<<gpe)) {
+ status = acpi_get_gpe_device(gpe, &handle);
+ if (ACPI_SUCCESS(status)) {
+ pr_info("Masking GPE 0x%x.\n", gpe);
+ (void)acpi_mask_gpe(handle, gpe, TRUE);
+ }
+ }
+ }
+}
+
void acpi_irq_stats_init(void)
{
acpi_status status;
--
1.7.10