On Wed, Nov 27, 2013 at 3:19 PM, Khalid Aziz <khalid.aziz at oracle.com> wrote: > 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 Applied to my for-linus branch for v3.13, thanks! Bjorn > --- > Changes since v1: > - Moved kexec_in_progress flag from pci.h to kexec.h > - Changed the type for kexec_in_progress flag to bool > - Added #ifdef CONFIG_KEXEC to code in pci-driver.c to > ensure it builds with CONFIG_KEXEC not set. > > drivers/pci/pci-driver.c | 12 +++++++++--- > include/linux/kexec.h | 3 +++ > kernel/kexec.c | 4 ++++ > 3 files changed, 16 insertions(+), 3 deletions(-) > > diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c > index 9042fdb..8eca81a 100644 > --- a/drivers/pci/pci-driver.c > +++ b/drivers/pci/pci-driver.c > @@ -19,6 +19,7 @@ > #include <linux/cpu.h> > #include <linux/pm_runtime.h> > #include <linux/suspend.h> > +#include <linux/kexec.h> > #include "pci.h" > > struct pci_dynid { > @@ -399,12 +400,17 @@ static void pci_device_shutdown(struct device *dev) > pci_msi_shutdown(pci_dev); > pci_msix_shutdown(pci_dev); > > +#ifdef CONFIG_KEXEC > /* > - * 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); > +#endif > } > > #ifdef CONFIG_PM > diff --git a/include/linux/kexec.h b/include/linux/kexec.h > index d78d28a..5fd33dc 100644 > --- a/include/linux/kexec.h > +++ b/include/linux/kexec.h > @@ -198,6 +198,9 @@ extern u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4]; > extern size_t vmcoreinfo_size; > extern size_t vmcoreinfo_max_size; > > +/* flag to track if kexec reboot is in progress */ > +extern bool kexec_in_progress; > + > int __init parse_crashkernel(char *cmdline, unsigned long long system_ram, > unsigned long long *crash_size, unsigned long long *crash_base); > int parse_crashkernel_high(char *cmdline, unsigned long long system_ram, > diff --git a/kernel/kexec.c b/kernel/kexec.c > index 490afc0..d0d8fca 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 */ > +bool kexec_in_progress = false; > + > /* 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 = true; > kernel_restart_prepare(NULL); > printk(KERN_EMERG "Starting new kernel\n"); > machine_shutdown(); > -- > 1.8.3.2 >
