commit 52d6b926aa upstream.
There is a race when taking a CPU offline. Current code looks like this:
native_cpu_disable()
{
...
apic_soft_disable();
/*
* Any existing set bits for pending interrupt to
* this CPU are preserved and will be sent via IPI
* to another CPU by fixup_irqs().
*/
cpu_disable_common();
{
....
/*
* Race window happens here. Once local APIC has been
* disabled any new interrupts from the device to
* the old CPU are lost
*/
fixup_irqs(); // Too late to capture anything in IRR.
...
}
}
The fix is to disable the APIC *after* cpu_disable_common().
Testing was done with a USB NIC that provided a source of frequent
interrupts. A script migrated interrupts to a specific CPU and
then took that CPU offline.
Fixes: 60dcaad573 ("x86/hotplug: Silence APIC and NMI when CPU is dead")
Reported-by: Evan Green <evgreen@chromium.org>
Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Tested-by: Evan Green <evgreen@chromium.org>
Reviewed-by: Evan Green <evgreen@chromium.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/lkml/875zdarr4h.fsf@nanos.tec.linutronix.de/
Link: https://lore.kernel.org/r/1598501530-45821-1-git-send-email-ashok.raj@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1adf8c19f9