From d509af9b5a31e2e836da6bd042d941e0ec54f468 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 ebe8c44fc610abbf6726bf720acbe3862b13a0c1
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 b4533a86d7e41..e79dbb95482b8 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;
--
2.39.5