On 3/6/20 10:32 AM, Kuppuswamy Sathyanarayanan wrote:
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@xxxxxxxxxxxxxxx>
Tested-by: Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
Fixes: 390e2db82480 ("PCI/AER: Abstract AER interrupt handling")
This patch is merged in v4.20 kernel. So this fix could be a candidate
for stable fix.
Reported-by: sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
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
