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author | Jan Beulich <jbeulich@novell.com> | 2011-08-22 10:11:10 +0100 |
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committer | Jan Beulich <jbeulich@novell.com> | 2011-08-22 10:11:10 +0100 |
commit | 2fba91e1d95292860076efce894c850413de8a15 (patch) | |
tree | e7c589c0eadc7f6ee8c9336fa2281fa9582e859b /xen/arch/x86/io_apic.c | |
parent | a370caf38d8a52129521736e217cfe20dcb51982 (diff) | |
download | xen-2fba91e1d95292860076efce894c850413de8a15.tar.gz xen-2fba91e1d95292860076efce894c850413de8a15.tar.bz2 xen-2fba91e1d95292860076efce894c850413de8a15.zip |
x86/IO-APIC: clear remoteIRR in clear_IO_APIC_pin()
It was found that in a crash scenario, the remoteIRR bit in an IO-APIC
RTE could be left set, causing problems when bringing up a kdump
kernel. While this generally is most important to be taken care of in
the new kernel (which usually would be a native one), it still seems
desirable to also address this problem in Xen so that (a) the problem
doesn't bite Xen when used as a secondary emergency kernel and (b) an
attempt is being made to save un-fixed secondary kernels from running
into said problem.
Based on a Linux patch from suresh.b.siddha@intel.com.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Diffstat (limited to 'xen/arch/x86/io_apic.c')
-rw-r--r-- | xen/arch/x86/io_apic.c | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/xen/arch/x86/io_apic.c b/xen/arch/x86/io_apic.c index 09caaf45de..f9565df58b 100644 --- a/xen/arch/x86/io_apic.c +++ b/xen/arch/x86/io_apic.c @@ -382,11 +382,46 @@ static void clear_IO_APIC_pin(unsigned int apic, unsigned int pin) return; /* + * Make sure the entry is masked and re-read the contents to check + * if it is a level triggered pin and if the remoteIRR is set. + */ + if (!entry.mask) { + entry.mask = 1; + __ioapic_write_entry(apic, pin, FALSE, entry); + } + entry = __ioapic_read_entry(apic, pin, TRUE); + + if (entry.irr) { + /* Make sure the trigger mode is set to level. */ + if (!entry.trigger) { + entry.trigger = 1; + __ioapic_write_entry(apic, pin, TRUE, entry); + } + if (mp_ioapics[apic].mpc_apicver >= 0x20) + io_apic_eoi(apic, entry.vector); + else { + /* + * Mechanism by which we clear remoteIRR in this case is by + * changing the trigger mode to edge and back to level. + */ + entry.trigger = 0; + __ioapic_write_entry(apic, pin, TRUE, entry); + entry.trigger = 1; + __ioapic_write_entry(apic, pin, TRUE, entry); + } + } + + /* * Disable it in the IO-APIC irq-routing table: */ memset(&entry, 0, sizeof(entry)); entry.mask = 1; __ioapic_write_entry(apic, pin, TRUE, entry); + + entry = __ioapic_read_entry(apic, pin, TRUE); + if (entry.irr) + printk(KERN_ERR "IO-APIC%02x-%u: Unable to reset IRR\n", + IO_APIC_ID(apic), pin); } static void clear_IO_APIC (void) |