From b566a22c23327f18ce941ffad0ca907e50a53d41 Mon Sep 17 00:00:00 2001 From: Khalid Aziz Date: Fri, 27 Apr 2012 13:00:33 -0600 Subject: [PATCH] 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 Signed-off-by: Bjorn Helgaas --- drivers/pci/pci-driver.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index 6b54b23..bf0cee6 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -421,6 +421,12 @@ static void pci_device_shutdown(struct device *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. * ACPI S5). Therefore disable wakeup for all devices that aren't -- 2.7.4