diff options
authorKhalid Aziz <>2013-11-27 15:19:25 -0700
committerBjorn Helgaas <>2013-12-07 14:20:28 -0700
commit4fc9bbf98fd66f879e628d8537ba7c240be2b58e (patch)
parentf407dae76040c9529c2c83b1488dda4ffc54522c (diff)
PCI: Disable Bus Master only on kexec reboot
Add a flag to tell the PCI subsystem that kernel is shutting down in preparation to kexec a kernel. Add code in PCI subsystem to use this flag to clear Bus Master bit on PCI devices only in case of kexec reboot. This fixes a power-off problem on Acer Aspire V5-573G and likely other machines and avoids any other issues caused by clearing Bus Master bit on PCI devices in normal shutdown path. The problem was introduced by b566a22c2332 ("PCI: disable Bus Master on PCI device shutdown"). This patch is based on discussion at Link: Reported-by: Chang Liu <> Signed-off-by: Khalid Aziz <> Signed-off-by: Bjorn Helgaas <> Acked-by: Konstantin Khlebnikov <> Cc: # v3.5+
3 files changed, 16 insertions, 3 deletions
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 7edd5c307446..25f0bc659164 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -19,6 +19,7 @@
#include <linux/cpu.h>
#include <linux/pm_runtime.h>
#include <linux/suspend.h>
+#include <linux/kexec.h>
#include "pci.h"
struct pci_dynid {
@@ -415,12 +416,17 @@ static void pci_device_shutdown(struct device *dev)
- * Turn off Bus Master bit on the device to tell it to not
- * continue to do DMA. Don't touch devices in D3cold or unknown states.
+ * If this is a kexec reboot, turn off Bus Master bit on the
+ * device to tell it to not continue to do DMA. Don't touch
+ * devices in D3cold or unknown states.
+ * If it is not a kexec reboot, firmware will hit the PCI
+ * devices with big hammer and stop their DMA any way.
- if (pci_dev->current_state <= PCI_D3hot)
+ if (kexec_in_progress && (pci_dev->current_state <= PCI_D3hot))
#ifdef CONFIG_PM
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index d78d28a733b1..5fd33dc1fe3a 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -198,6 +198,9 @@ extern u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4];
extern size_t vmcoreinfo_size;
extern size_t vmcoreinfo_max_size;
+/* flag to track if kexec reboot is in progress */
+extern bool kexec_in_progress;
int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
unsigned long long *crash_size, unsigned long long *crash_base);
int parse_crashkernel_high(char *cmdline, unsigned long long system_ram,
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 490afc03627e..d0d8fca54065 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -47,6 +47,9 @@ u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4];
size_t vmcoreinfo_size;
size_t vmcoreinfo_max_size = sizeof(vmcoreinfo_data);
+/* Flag to indicate we are going to kexec a new kernel */
+bool kexec_in_progress = false;
/* Location of the reserved area for the crash kernel */
struct resource crashk_res = {
.name = "Crash kernel",
@@ -1675,6 +1678,7 @@ int kernel_kexec(void)
} else
+ kexec_in_progress = true;
printk(KERN_EMERG "Starting new kernel\n");