Commit 4fc9bbf9 authored by Khalid Aziz's avatar Khalid Aziz Committed by Bjorn Helgaas
Browse files

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
b566a22c ("PCI: disable Bus Master on PCI device shutdown").

This patch is based on discussion at
http://marc.info/?l=linux-pci&m=138425645204355&w=2

Link: https://bugzilla.kernel.org/show_bug.cgi?id=63861


Reported-by: default avatarChang Liu <cl91tp@gmail.com>
Signed-off-by: default avatarKhalid Aziz <khalid.aziz@oracle.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Acked-by: default avatarKonstantin Khlebnikov <koct9i@gmail.com>
Cc: stable@vger.kernel.org	# v3.5+
parent f407dae7

drivers/pci/pci-driver.c

+9 −3
Original line number Diff line number Diff line
@@ -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) 
	pci_msi_shutdown(pci_dev);

	pci_msix_shutdown(pci_dev);



#ifdef CONFIG_KEXEC

	/*

	 * 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))

		pci_clear_master(pci_dev);

#endif

}



#ifdef CONFIG_PM

include/linux/kexec.h

+3 −0
Original line number Diff line number Diff line
@@ -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,

kernel/kexec.c

+4 −0
Original line number Diff line number Diff line
@@ -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

#endif

	{

		kexec_in_progress = true;

		kernel_restart_prepare(NULL);

		printk(KERN_EMERG "Starting new kernel\n");

		machine_shutdown();

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