[Xen-changelog] [xen-4.1-testing] x86/KEXEC: disable hpet legacy broadcasts earlier

[Xen patchbot-4.1-testing <patchbot@xxxxxxx>]

# HG changeset patch
# User Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
# Date 1313744425 -3600
# Node ID a79c1d5b946edce0f9f5b4bda061e2ad98adc4da
# Parent  98c98daab56afa001e966c803f242439645a23d0
x86/KEXEC: disable hpet legacy broadcasts earlier

On x2apic machines which booted in xapic mode,
hpet_disable_legacy_broadcast() sends an event check IPI to all online
processors.  This leads to a protection fault as the genapic blindly
pokes x2apic MSRs while the local apic is in xapic mode.

One option is to change genapic when we shut down the local apic, but
there are still problems with trying to IPI processors in the online
processor map which are actually sitting in NMI loops

Another option is to have each CPU take itself out of the online CPU
map during the NMI shootdown.

Realistically however, disabling hpet legacy broadcasts earlier in the
kexec path is the easiest fix to the problem.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
xen-unstable changeset:   23776:0ddb4481f883
xen-unstable date:        Fri Aug 19 09:58:22 2011 +0100
---


diff -r 98c98daab56a -r a79c1d5b946e xen/arch/x86/crash.c
--- a/xen/arch/x86/crash.c      Tue Aug 16 15:21:46 2011 +0100
+++ b/xen/arch/x86/crash.c      Fri Aug 19 10:00:25 2011 +0100
@@ -29,6 +29,7 @@
 #include <asm/io_apic.h>
 #include <xen/iommu.h>
 #include <xen/pci.h>
+#include <asm/hpet.h>
 
 static atomic_t waiting_for_crash_ipi;
 static unsigned int crashing_cpu;
@@ -61,6 +62,9 @@
 
     local_irq_disable();
 
+    if ( hpet_broadcast_is_available() )
+        hpet_disable_legacy_broadcast();
+
     crashing_cpu = smp_processor_id();
     local_irq_count(crashing_cpu) = 0;
 
diff -r 98c98daab56a -r a79c1d5b946e xen/arch/x86/machine_kexec.c
--- a/xen/arch/x86/machine_kexec.c      Tue Aug 16 15:21:46 2011 +0100
+++ b/xen/arch/x86/machine_kexec.c      Fri Aug 19 10:00:25 2011 +0100
@@ -96,9 +96,6 @@
         .limit = LAST_RESERVED_GDT_BYTE
     };
 
-    if ( hpet_broadcast_is_available() )
-        hpet_disable_legacy_broadcast();
-
     /* We are about to permenantly jump out of the Xen context into the kexec
      * purgatory code.  We really dont want to be still servicing interupts.
      */

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