Messages in this thread | | | Subject | Re: [patch 7/7] PCI/AER: Fix the broken interrupt injection | From | Kuppuswamy Sathyanarayanan <> | Date | Fri, 6 Mar 2020 10:32:43 -0800 |
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On 3/6/20 5:03 AM, Thomas Gleixner wrote: > The AER error injection mechanism just blindly abuses generic_handle_irq() > which is really not meant for consumption by random drivers. The include of > linux/irq.h should have been a red flag in the first place. Driver code, > unless implementing interrupt chips or low level hypervisor functionality > has absolutely no business with that. > > Invoking generic_handle_irq() from non interrupt handling context can have > nasty side effects at least on x86 due to the hardware trainwreck which > makes interrupt affinity changes a fragile beast. Sathyanarayanan triggered > a NULL pointer dereference in the low level APIC code that way. While the > particular pointer could be checked this would only paper over the issue > because there are other ways to trigger warnings or silently corrupt state. > > Invoke the new irq_inject_interrupt() mechanism, which has the necessary > sanity checks in place and injects the interrupt via the irq_retrigger() > mechanism, which is at least halfways safe vs. the fragile x86 affinity > change mechanics. > > It's safe on x86 as it does not corrupt state, but it still can cause a > premature completion of an interrupt affinity change causing the interrupt > line to become stale. Very unlikely, but possible. > > For regular operations this is a non issue as AER error injection is meant > for debugging and testing and not for usage on production systems. People > using this should better know what they are doing. It looks good to me.
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> Tested-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> > > Fixes: 390e2db82480 ("PCI/AER: Abstract AER interrupt handling") > Reported-by: sathyanarayanan.kuppuswamy@linux.intel.com > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > --- > drivers/pci/pcie/Kconfig | 1 + > drivers/pci/pcie/aer_inject.c | 6 ++---- > 2 files changed, 3 insertions(+), 4 deletions(-) > > --- a/drivers/pci/pcie/Kconfig > +++ b/drivers/pci/pcie/Kconfig > @@ -34,6 +34,7 @@ config PCIEAER > config PCIEAER_INJECT > tristate "PCI Express error injection support" > depends on PCIEAER > + select GENERIC_IRQ_INJECTION > help > This enables PCI Express Root Port Advanced Error Reporting > (AER) software error injector. > --- a/drivers/pci/pcie/aer_inject.c > +++ b/drivers/pci/pcie/aer_inject.c > @@ -16,7 +16,7 @@ > > #include <linux/module.h> > #include <linux/init.h> > -#include <linux/irq.h> > +#include <linux/interrupt.h> > #include <linux/miscdevice.h> > #include <linux/pci.h> > #include <linux/slab.h> > @@ -468,9 +468,7 @@ static int aer_inject(struct aer_error_i > } > pci_info(edev->port, "Injecting errors %08x/%08x into device %s\n", > einj->cor_status, einj->uncor_status, pci_name(dev)); > - local_irq_disable(); > - generic_handle_irq(edev->irq); > - local_irq_enable(); > + ret = irq_inject_interrupt(edev->irq); > } else { > pci_err(rpdev, "AER device not found\n"); > ret = -ENODEV; > -- Sathyanarayanan Kuppuswamy Linux kernel developer
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