Add a flag to tell the PCI subsystem that kernel is shutting down in prepapration to kexec a kernel. Add code in PCI subsystem to use this flag to clear Bus Master bit on PCI devices only in case of kexec reboot. This fixes https://bugzilla.kernel.org/show_bug.cgi?id=63861 and avoids any other issues caused by clearing Bus Master bit on PCI devices in normal shutdown path. This patch is based on discussion at http://marc.info/?l=linux-pci&m=138425645204355&w=2 Signed-off-by: Khalid Aziz <khalid.aziz at oracle.com> Acked-by: Konstantin Khlebnikov <koct9i at gmail.com> Cc: stable at vger.kernel.org --- drivers/pci/pci-driver.c | 9 ++++++--- drivers/pci/pci.h | 3 +++ kernel/kexec.c | 4 ++++ 3 files changed, 13 insertions(+), 3 deletions(-) diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index 9042fdb..e920195 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -400,10 +400,13 @@ 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. Don't touch devices in D3cold or unknown states. + * If this is a kexec reboot, turn off Bus Master bit on the + * device to tell it to not continue to do DMA. Don't touch + * devices in D3cold or unknown states. + * If it is not a kexec reboot, firmware will hit the PCI + * devices with big hammer and stop their DMA any way. */ - if (pci_dev->current_state <= PCI_D3hot) + if (kexec_in_progress && (pci_dev->current_state <= PCI_D3hot)) pci_clear_master(pci_dev); } diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h index 9c91ecc..7d85733 100644 --- a/drivers/pci/pci.h +++ b/drivers/pci/pci.h @@ -9,6 +9,9 @@ extern const unsigned char pcix_bus_speed[]; extern const unsigned char pcie_link_speed[]; +/* flag to track if kexec reboot is in progress */ +extern unsigned long kexec_in_progress; + /* Functions internal to the PCI core code */ int pci_create_sysfs_dev_files(struct pci_dev *pdev); diff --git a/kernel/kexec.c b/kernel/kexec.c index 490afc0..fd2d63e 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -47,6 +47,9 @@ u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4]; size_t vmcoreinfo_size; size_t vmcoreinfo_max_size = sizeof(vmcoreinfo_data); +/* Flag to indicate we are going to kexec a new kernel */ +unsigned long kexec_in_progress = 0; + /* Location of the reserved area for the crash kernel */ struct resource crashk_res = { .name = "Crash kernel", @@ -1675,6 +1678,7 @@ int kernel_kexec(void) } else #endif { + kexec_in_progress = 1; kernel_restart_prepare(NULL); printk(KERN_EMERG "Starting new kernel\n"); machine_shutdown(); -- 1.8.3.2
