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PCI: disable Bus Master on PCI device shutdown

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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>
This commit is contained in:
Khalid Aziz 2012-04-27 13:00:33 -06:00 • committed by Bjorn Helgaas
commit b566a22c23
1 changed files with 6 additions and 0 deletions
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6
drivers/pci/pci-driver.c
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@ -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.