linux-kernel - [RFC PATCH 2/7] context_tracking: Move guest enter/exit logic to standalone helpers

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Date:   Tue, 13 Apr 2021 11:29:28 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Michael Tokarev <mjt@....msk.ru>
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 <seanjc@...gle.com>
---
 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