linux-kernel - [RFC PATCH 4/7] context_tracking: KVM: Move guest enter/exit wrappers to KVM's domain

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Message-Id: <20210413182933.1046389-5-seanjc@google.com>
Date:   Tue, 13 Apr 2021 11:29:30 -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 4/7] context_tracking: KVM: Move guest enter/exit wrappers
 to KVM's domain

Move the guest enter/exit wrappers to kvm_host.h so that KVM can manage
its context tracking vs. vtime accounting without bleeding too many KVM
details into the context tracking code.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 include/linux/context_tracking.h | 45 --------------------------------
 include/linux/kvm_host.h         | 45 ++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 45 deletions(-)

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index ded56aed539a..2f4538380a8d 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -126,49 +126,4 @@ extern void context_tracking_init(void);
 static inline void context_tracking_init(void) { }
 #endif /* CONFIG_CONTEXT_TRACKING_FORCE */
 
-/* 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();
-	vtime_account_guest_enter();
-	instrumentation_end();
-
-	/*
-	 * 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_guest_enter_irqoff()) {
-		instrumentation_begin();
-		rcu_virt_note_context_switch(smp_processor_id());
-		instrumentation_end();
-	}
-}
-
-static __always_inline void guest_exit_irqoff(void)
-{
-	context_tracking_guest_exit_irqoff();
-
-	instrumentation_begin();
-	/* Flush the guest cputime we spent on the guest */
-	vtime_account_guest_exit();
-	instrumentation_end();
-}
-
-static inline void guest_exit(void)
-{
-	unsigned long flags;
-
-	local_irq_save(flags);
-	guest_exit_irqoff();
-	local_irq_restore(flags);
-}
-
 #endif
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 3b06d12ec37e..444d5f0225cb 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -332,6 +332,51 @@ struct kvm_vcpu {
 	struct kvm_dirty_ring dirty_ring;
 };
 
+/* 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();
+	vtime_account_guest_enter();
+	instrumentation_end();
+
+	/*
+	 * 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_guest_enter_irqoff()) {
+		instrumentation_begin();
+		rcu_virt_note_context_switch(smp_processor_id());
+		instrumentation_end();
+	}
+}
+
+static __always_inline void guest_exit_irqoff(void)
+{
+	context_tracking_guest_exit_irqoff();
+
+	instrumentation_begin();
+	/* Flush the guest cputime we spent on the guest */
+	vtime_account_guest_exit();
+	instrumentation_end();
+}
+
+static inline void guest_exit(void)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	guest_exit_irqoff();
+	local_irq_restore(flags);
+}
+
 static inline int kvm_vcpu_exiting_guest_mode(struct kvm_vcpu *vcpu)
 {
 	/*
-- 
2.31.1.295.g9ea45b61b8-goog