Merge tag 'stable/for-linus-fixes-3.3-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen

Two fixes for VCPU offlining; One to fix the string format exposed
by the xen-pci[front|back] to conform to the one used in majority of
PCI drivers; Two fixes to make the code more resilient to invalid
configurations.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

* tag 'stable/for-linus-fixes-3.3-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
  xenbus_dev: add missing error check to watch handling
  xen/pci[front|back]: Use %d instead of %1x for displaying PCI devfn.
  xen pvhvm: do not remap pirqs onto evtchns if !xen_have_vector_callback
  xen/smp: Fix CPU online/offline bug triggering a BUG: scheduling while atomic.
  xen/bootup: During bootup suppress XENBUS: Unable to read cpu state

2 files changed, 8 insertions, 1 deletions

diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
index 492ade8c978..d99346ea8fd 100644
--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c
@@ -374,7 +374,7 @@ int __init pci_xen_init(void)
 
 int __init pci_xen_hvm_init(void)
 {
-        if (!xen_feature(XENFEAT_hvm_pirqs))
+        if (!xen_have_vector_callback || !xen_feature(XENFEAT_hvm_pirqs))
                 return 0;
 
 #ifdef CONFIG_ACPI
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index 041d4fe9dfe..501d4e0244b 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -409,6 +409,13 @@ static void __cpuinit xen_play_dead(void) /* used only with HOTPLUG_CPU */
         play_dead_common();
         HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL);
         cpu_bringup();
+        /*
+         * Balance out the preempt calls - as we are running in cpu_idle
+         * loop which has been called at bootup from cpu_bringup_and_idle.
+         * The cpucpu_bringup_and_idle called cpu_bringup which made a
+         * preempt_disable() So this preempt_enable will balance it out.
+         */
+        preempt_enable();
 }
 
 #else /* !CONFIG_HOTPLUG_CPU */