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Commit b566a22c authored by Khalid Aziz's avatar Khalid Aziz Committed by Bjorn Helgaas
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PCI: disable Bus Master on PCI device shutdown 



Disable Bus Master bit on the device in pci_device_shutdown() to ensure PCI
devices do not continue to DMA data after shutdown.  This can cause memory
corruption in case of a kexec where the current kernel shuts down and
transfers control to a new kernel while a PCI device continues to DMA to
memory that does not belong to it any more in the new kernel.

I have tested this code on two laptops, two workstations and a 16-socket
server.  kexec worked correctly on all of them.

Signed-off-by: default avatarKhalid Aziz <khalid.aziz@hp.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent df558de1

drivers/pci/pci-driver.c

+6 −0
Original line number Diff line number Diff line
@@ -420,6 +420,12 @@ static void pci_device_shutdown(struct device *dev) 
	pci_msi_shutdown(pci_dev);

	pci_msix_shutdown(pci_dev);



	/*

	 * Turn off Bus Master bit on the device to tell it to not

	 * continue to do DMA

	 */

	pci_disable_device(pci_dev);



	/*

	 * Devices may be enabled to wake up by runtime PM, but they need not

	 * be supposed to wake up the system from its "power off" state (e.g.