Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

[cascardo/linux.git] / include / linux / context_tracking.h

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index d9aef2a..c78fc27 100644 (file)
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -99,7 +99,8 @@ static inline void context_tracking_init(void) { }
 
 
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
-static inline void guest_enter(void)
+/* must be called with irqs disabled */
+static inline void guest_enter_irqoff(void)
 {
        if (vtime_accounting_cpu_enabled())
                vtime_guest_enter(current);
@@ -108,9 +109,19 @@ static inline void guest_enter(void)
 
        if (context_tracking_is_enabled())
                __context_tracking_enter(CONTEXT_GUEST);
+
+       /* KVM does not hold any references to rcu protected data when it
+        * switches CPU into a guest mode. In fact switching to a guest mode
+        * is very similar to exiting to userspace from rcu point of view. In
+        * addition CPU may stay in a guest mode for quite a long time (up to
+        * one time slice). Lets treat guest mode as quiescent state, just like
+        * we do with user-mode execution.
+        */
+       if (!context_tracking_cpu_is_enabled())
+               rcu_virt_note_context_switch(smp_processor_id());
 }
 
-static inline void guest_exit(void)
+static inline void guest_exit_irqoff(void)
 {
        if (context_tracking_is_enabled())
                __context_tracking_exit(CONTEXT_GUEST);
@@ -122,7 +133,7 @@ static inline void guest_exit(void)
 }
 
 #else
-static inline void guest_enter(void)
+static inline void guest_enter_irqoff(void)
 {
        /*
         * This is running in ioctl context so its safe
@@ -131,9 +142,10 @@ static inline void guest_enter(void)
         */
        vtime_account_system(current);
        current->flags |= PF_VCPU;
+       rcu_virt_note_context_switch(smp_processor_id());
 }
 
-static inline void guest_exit(void)
+static inline void guest_exit_irqoff(void)
 {
        /* Flush the guest cputime we spent on the guest */
        vtime_account_system(current);
@@ -141,4 +153,22 @@ static inline void guest_exit(void)
 }
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */
 
+static inline void guest_enter(void)
+{
+       unsigned long flags;
+
+       local_irq_save(flags);
+       guest_enter_irqoff();
+       local_irq_restore(flags);
+}
+
+static inline void guest_exit(void)
+{
+       unsigned long flags;
+
+       local_irq_save(flags);
+       guest_exit_irqoff();
+       local_irq_restore(flags);
+}
+
 #endif