x86/paravirt: make arch_flush_lazy_mmu/cpu disable preemption

Impact: avoid access to percpu vars in preempible context

They are intended to be used whenever there's the possibility
that there's some stale state which is going to be overwritten
with a queued update, or to force a state change when we may be
in lazy mode.  Either way, we could end up calling it with
preemption enabled, so wrap the functions in their own little
preempt-disable section so they can be safely called in any
context (though preemption should never be enabled if we're actually
in a lazy state).

(Move out of line to avoid #include dependencies.)
    
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 24 insertions, 0 deletions

diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index e4c8fb608873..dcba6c567a2a 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -268,6 +268,30 @@ enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
         return __get_cpu_var(paravirt_lazy_mode);
 }
 
+void arch_flush_lazy_mmu_mode(void)
+{
+        preempt_disable();
+
+        if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
+                arch_leave_lazy_mmu_mode();
+                arch_enter_lazy_mmu_mode();
+        }
+
+        preempt_enable();
+}
+
+void arch_flush_lazy_cpu_mode(void)
+{
+        preempt_disable();
+
+        if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_CPU) {
+                arch_leave_lazy_cpu_mode();
+                arch_enter_lazy_cpu_mode();
+        }
+
+        preempt_enable();
+}
+
 struct pv_info pv_info = {
         .name = "bare hardware",
         .paravirt_enabled = 0,