This is a note to let you know that I've just added the patch titled

    xen: Do not enable PV IPIs when vector callback not present

to the 3.0-stable tree which can be found at:
    
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     xen-do-not-enable-pv-ipis-when-vector-callback-not-present.patch
and it can be found in the queue-3.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <sta...@kernel.org> know about it.


>From 3c05c4bed4ccce3f22f6d7899b308faae24ad198 Mon Sep 17 00:00:00 2001
From: Stefano Stabellini <stefano.stabell...@eu.citrix.com>
Date: Wed, 17 Aug 2011 15:15:00 +0200
Subject: xen: Do not enable PV IPIs when vector callback not present

From: Stefano Stabellini <stefano.stabell...@eu.citrix.com>

commit 3c05c4bed4ccce3f22f6d7899b308faae24ad198 upstream.

Fix regression for HVM case on older (<4.1.1) hypervisors caused by

  commit 99bbb3a84a99cd04ab16b998b20f01a72cfa9f4f
  Author: Stefano Stabellini <stefano.stabell...@eu.citrix.com>
  Date:   Thu Dec 2 17:55:10 2010 +0000

    xen: PV on HVM: support PV spinlocks and IPIs

This change replaced the SMP operations with event based handlers without
taking into account that this only works when the hypervisor supports
callback vectors. This causes unexplainable hangs early on boot for
HVM guests with more than one CPU.

BugLink: http://bugs.launchpad.net/bugs/791850

Signed-off-by: Stefan Bader <stefan.ba...@canonical.com>
Signed-off-by: Stefano Stabellini <stefano.stabell...@eu.citrix.com>
Tested-and-Reported-by: Stefan Bader <stefan.ba...@canonical.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gre...@suse.de>

---
 arch/x86/xen/smp.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -521,8 +521,6 @@ static void __init xen_hvm_smp_prepare_c
        native_smp_prepare_cpus(max_cpus);
        WARN_ON(xen_smp_intr_init(0));
 
-       if (!xen_have_vector_callback)
-               return;
        xen_init_lock_cpu(0);
        xen_init_spinlocks();
 }
@@ -546,6 +544,8 @@ static void xen_hvm_cpu_die(unsigned int
 
 void __init xen_hvm_smp_init(void)
 {
+       if (!xen_have_vector_callback)
+               return;
        smp_ops.smp_prepare_cpus = xen_hvm_smp_prepare_cpus;
        smp_ops.smp_send_reschedule = xen_smp_send_reschedule;
        smp_ops.cpu_up = xen_hvm_cpu_up;


Patches currently in stable-queue which might be from 
stefano.stabell...@eu.citrix.com are

queue-3.0/xen-blkfront-drop-name-and-minor-adjustments-for-emulated.patch
queue-3.0/xen-blkfront-fix-one-off-warning-about-name-clash.patch
queue-3.0/xen-do-not-enable-pv-ipis-when-vector-callback-not-present.patch

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