linux-kernel - [PATCH v4 2/8] context_tracking: Move guest exit vtime accounting to separate helpers

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Date:   Tue,  4 May 2021 17:27:29 -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>,
        Michael Tokarev <mjt@....msk.ru>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Frederic Weisbecker <frederic@...nel.org>
Subject: [PATCH v4 2/8] context_tracking: Move guest exit vtime accounting to
 separate helpers

From: Wanpeng Li <wanpengli@...cent.com>

Provide separate vtime accounting functions for guest exit instead of
open coding the logic within the context tracking code.  This will allow
KVM x86 to handle vtime accounting slightly differently when using
tick-based accounting.

Suggested-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Michael Tokarev <mjt@....msk.ru>
Cc: Frederic Weisbecker <frederic@...nel.org>
Reviewed-by: Christian Borntraeger <borntraeger@...ibm.com>
Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
Co-developed-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 include/linux/context_tracking.h | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index b8c7313495a7..4f4556232dcf 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -137,15 +137,20 @@ static __always_inline void context_tracking_guest_exit(void)
 		__context_tracking_exit(CONTEXT_GUEST);
 }
 
-static __always_inline void guest_exit_irqoff(void)
+static __always_inline void vtime_account_guest_exit(void)
 {
-	context_tracking_guest_exit();
-
-	instrumentation_begin();
 	if (vtime_accounting_enabled_this_cpu())
 		vtime_guest_exit(current);
 	else
 		current->flags &= ~PF_VCPU;
+}
+
+static __always_inline void guest_exit_irqoff(void)
+{
+	context_tracking_guest_exit();
+
+	instrumentation_begin();
+	vtime_account_guest_exit();
 	instrumentation_end();
 }
 
@@ -166,12 +171,17 @@ static __always_inline void guest_enter_irqoff(void)
 
 static __always_inline void context_tracking_guest_exit(void) { }
 
-static __always_inline void guest_exit_irqoff(void)
+static __always_inline void vtime_account_guest_exit(void)
 {
-	instrumentation_begin();
-	/* Flush the guest cputime we spent on the guest */
 	vtime_account_kernel(current);
 	current->flags &= ~PF_VCPU;
+}
+
+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 */
-- 
2.31.1.527.g47e6f16901-goog