From b566a22c23327f18ce941ffad0ca907e50a53d41 Mon Sep 17 00:00:00 2001 From: Khalid Aziz <khalid.aziz@hp.com> 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 <khalid.aziz@hp.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> --- 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 6b54b23b990be..bf0cee629b60f 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -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. -- GitLab