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x86, kdump, ioapic: Reset remote-IRR in clear_IO_APIC 

In the kdump scenario mentioned below, we can have a case where
the device using level triggered interrupt will not generate any
interrupts in the kdump kernel.

1. IO-APIC sends a level triggered interrupt to the CPU's local APIC.

2. Kernel crashed before the CPU services this interrupt, leaving
   the remote-IRR in the IO-APIC set.

3. kdump kernel boot sequence does clear_IO_APIC() as part of IO-APIC
   initialization. But this fails to reset remote-IRR bit of the
   IO-APIC RTE as the remote-IRR bit is read-only.

4. Device using that level triggered entry can't generate any
   more interrupts because of the remote-IRR bit.

In clear_IO_APIC_pin(), check if the remote-IRR bit is set and if
so do an explicit attempt to clear it (by doing EOI write on
modern io-apic's and changing trigger mode to edge/level on
older io-apic's). Also before doing the explicit EOI to the
io-apic, ensure that the trigger mode is indeed set to level.
This will enable the explicit EOI to the io-apic to reset the
remote-IRR bit.

Tested-by: Leonardo Chiquitto <lchiquitto@novell.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Fixes: https://bugzilla.novell.com/show_bug.cgi?id=701686
Cc: Rafael Wysocki <rjw@novell.com>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Thomas Renninger <trenn@suse.de>
Cc: jbeulich@novell.com
Cc: yinghai@kernel.org
Link: http://lkml.kernel.org/r/20110825190657.157502602@sbsiddha-desk.sc.intel.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Suresh Siddha 2011-08-25 12:01:11 -07:00 committed by Ingo Molnar
parent d3f138106b
commit 1e75b31d63
1 changed files with 47 additions and 1 deletions
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48
arch/x86/kernel/apic/io_apic.c
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@ -593,10 +593,56 @@ static void clear_IO_APIC_pin(unsigned int apic, unsigned int pin)
entry = ioapic_read_entry(apic, pin);
if (entry.delivery_mode == dest_SMI)
return;
/*
* Disable it in the IO-APIC irq-routing table:
* Make sure the entry is masked and re-read the contents to check
* if it is a level triggered pin and if the remote-IRR is set.
*/
if (!entry.mask) {
entry.mask = 1;
ioapic_write_entry(apic, pin, entry);
entry = ioapic_read_entry(apic, pin);
}
if (entry.irr) {
/*
* Make sure the trigger mode is set to level. Explicit EOI
* doesn't clear the remote-IRR if the trigger mode is not
* set to level.
*/
if (!entry.trigger) {
entry.trigger = IOAPIC_LEVEL;
ioapic_write_entry(apic, pin, entry);
}
if (mpc_ioapic_ver(apic) >= 0x20) {
unsigned long flags;
raw_spin_lock_irqsave(&ioapic_lock, flags);
io_apic_eoi(apic, entry.vector);
raw_spin_unlock_irqrestore(&ioapic_lock, flags);
} else {
/*
* Mechanism by which we clear remote-IRR in this
* case is by changing the trigger mode to edge and
* back to level.
*/
entry.trigger = IOAPIC_EDGE;
ioapic_write_entry(apic, pin, entry);
entry.trigger = IOAPIC_LEVEL;
ioapic_write_entry(apic, pin, entry);
}
}
/*
* Clear the rest of the bits in the IO-APIC RTE except for the mask
* bit.
*/
ioapic_mask_entry(apic, pin);
entry = ioapic_read_entry(apic, pin);
if (entry.irr)
printk(KERN_ERR "Unable to reset IRR for apic: %d, pin :%d\n",
mpc_ioapic_id(apic), pin);
}
static void clear_IO_APIC (void)