From 3c05c4bed4ccce3f22f6d7899b308faae24ad198 Mon Sep 17 00:00:00 2001
From: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Date: Wed, 17 Aug 2011 15:15:00 +0200
Subject: [PATCH] xen: Do not enable PV IPIs when vector callback not present
Fix regression for HVM case on older (<4.1.1) hypervisors caused by
commit 99bbb3a84a99cd04ab16b998b20f01a72cfa9f4f
Author: Stefano Stabellini <stefano.stabellini@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
CC: stable@kernel.org
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Tested-and-Reported-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
arch/x86/xen/smp.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index b4533a86d7e410..e79dbb95482b84 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -521,8 +521,6 @@ static void __init xen_hvm_smp_prepare_cpus(unsigned int max_cpus)
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 cpu)
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;
--
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