2021-04-13 22:56:25

by Sean Christopherson

[permalink] [raw]
Subject: [RFC PATCH 2/7] context_tracking: Move guest enter/exit logic to standalone helpers

Move guest enter/exit context tracking to standalone helpers, so that the
existing wrappers can be moved under KVM.

No functional change intended.

Signed-off-by: Sean Christopherson <[email protected]>
---
include/linux/context_tracking.h | 43 +++++++++++++++++++-------------
1 file changed, 26 insertions(+), 17 deletions(-)

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index 58f9a7251d3b..89a1a5ccb2ab 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -71,6 +71,30 @@ static inline void exception_exit(enum ctx_state prev_ctx)
}
}

+static __always_inline void context_tracking_guest_enter_irqoff(void)
+{
+ if (context_tracking_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_enabled_this_cpu()) {
+ instrumentation_begin();
+ rcu_virt_note_context_switch(smp_processor_id());
+ instrumentation_end();
+ }
+}
+
+static __always_inline void context_tracking_guest_exit_irqoff(void)
+{
+ if (context_tracking_enabled())
+ __context_tracking_exit(CONTEXT_GUEST);
+}

/**
* ct_state() - return the current context tracking state if known
@@ -110,27 +134,12 @@ static __always_inline void guest_enter_irqoff(void)
vtime_account_guest_enter();
instrumentation_end();

- if (context_tracking_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_enabled_this_cpu()) {
- instrumentation_begin();
- rcu_virt_note_context_switch(smp_processor_id());
- instrumentation_end();
- }
+ context_tracking_guest_enter_irqoff();
}

static __always_inline void guest_exit_irqoff(void)
{
- if (context_tracking_enabled())
- __context_tracking_exit(CONTEXT_GUEST);
+ context_tracking_guest_exit_irqoff();

instrumentation_begin();
vtime_account_guest_exit();
--
2.31.1.295.g9ea45b61b8-goog