linux-kernel - [tip: x86/urgent] context_tracking: Consolidate guest enter/exit wrappers

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Message-ID: <162030324327.29796.6542362933513475728.tip-bot2@tip-bot2>
Date:   Thu, 06 May 2021 12:14:03 -0000
From:   "tip-bot2 for Sean Christopherson" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/urgent] context_tracking: Consolidate guest enter/exit wrappers

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     14296e0c447885d6c7b326e059fb528eb00526ed
Gitweb:        https://git.kernel.org/tip/14296e0c447885d6c7b326e059fb528eb00526ed
Author:        Sean Christopherson <seanjc@...gle.com>
AuthorDate:    Tue, 04 May 2021 17:27:33 -07:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Wed, 05 May 2021 22:54:11 +02:00

context_tracking: Consolidate guest enter/exit wrappers

Consolidate the guest enter/exit wrappers, providing and tweaking stubs
as needed.  This will allow moving the wrappers under KVM without having
to bleed #ifdefs into the soon-to-be KVM code.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Link: https://lore.kernel.org/r/20210505002735.1684165-7-seanjc@google.com

---
 include/linux/context_tracking.h | 65 +++++++++++--------------------
 1 file changed, 24 insertions(+), 41 deletions(-)

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index 56c648b..aa58c2a 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -71,6 +71,19 @@ static inline void exception_exit(enum ctx_state prev_ctx)
 	}
 }
 
+static __always_inline bool context_tracking_guest_enter(void)
+{
+	if (context_tracking_enabled())
+		__context_tracking_enter(CONTEXT_GUEST);
+
+	return context_tracking_enabled_this_cpu();
+}
+
+static __always_inline void context_tracking_guest_exit(void)
+{
+	if (context_tracking_enabled())
+		__context_tracking_exit(CONTEXT_GUEST);
+}
 
 /**
  * ct_state() - return the current context tracking state if known
@@ -92,6 +105,9 @@ static inline void user_exit_irqoff(void) { }
 static inline enum ctx_state exception_enter(void) { return 0; }
 static inline void exception_exit(enum ctx_state prev_ctx) { }
 static inline enum ctx_state ct_state(void) { return CONTEXT_DISABLED; }
+static inline bool context_tracking_guest_enter(void) { return false; }
+static inline void context_tracking_guest_exit(void) { }
+
 #endif /* !CONFIG_CONTEXT_TRACKING */
 
 #define CT_WARN_ON(cond) WARN_ON(context_tracking_enabled() && (cond))
@@ -102,74 +118,41 @@ extern void context_tracking_init(void);
 static inline void context_tracking_init(void) { }
 #endif /* CONFIG_CONTEXT_TRACKING_FORCE */
 
-
-#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
 /* must be called with irqs disabled */
 static __always_inline void guest_enter_irqoff(void)
 {
+	/*
+	 * This is running in ioctl context so its safe to assume that it's the
+	 * stime pending cputime to flush.
+	 */
 	instrumentation_begin();
-	if (vtime_accounting_enabled_this_cpu())
-		vtime_guest_enter(current);
-	else
-		current->flags |= PF_VCPU;
+	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
+	/*
+	 * 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()) {
+	if (!context_tracking_guest_enter()) {
 		instrumentation_begin();
 		rcu_virt_note_context_switch(smp_processor_id());
 		instrumentation_end();
 	}
 }
 
-static __always_inline void context_tracking_guest_exit(void)
-{
-	if (context_tracking_enabled())
-		__context_tracking_exit(CONTEXT_GUEST);
-}
-
 static __always_inline void guest_exit_irqoff(void)
 {
 	context_tracking_guest_exit();
 
 	instrumentation_begin();
-	vtime_account_guest_exit();
-	instrumentation_end();
-}
-
-#else
-static __always_inline void guest_enter_irqoff(void)
-{
-	/*
-	 * This is running in ioctl context so its safe
-	 * to assume that it's the stime pending cputime
-	 * to flush.
-	 */
-	instrumentation_begin();
-	vtime_account_guest_enter();
-	rcu_virt_note_context_switch(smp_processor_id());
-	instrumentation_end();
-}
-
-static __always_inline void context_tracking_guest_exit(void) { }
-
-static __always_inline void guest_exit_irqoff(void)
-{
-	instrumentation_begin();
 	/* Flush the guest cputime we spent on the guest */
 	vtime_account_guest_exit();
 	instrumentation_end();
 }
-#endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */
 
 static inline void guest_exit(void)
 {