Commit b566a22c authored Apr 27, 2012 by Khalid Aziz Committed by Bjorn Helgaas May 04, 2012

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: Khalid Aziz <khalid.aziz@hp.com>
Signed-off-by: Bjorn 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.

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