linux-kernel - [PATCH 5.10 5/9] context_tracking: Move guest exit vtime accounting to separate helpers

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Date:   Thu, 27 May 2021 17:12:57 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Wanpeng Li <wanpengli@...cent.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Christian Borntraeger <borntraeger@...ibm.com>
Subject: [PATCH 5.10 5/9] context_tracking: Move guest exit vtime accounting to separate helpers

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

commit 88d8220bbf06dd8045b2ac4be1046290eaa7773a upstream.

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>
Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
Co-developed-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Christian Borntraeger <borntraeger@...ibm.com>
Link: https://lore.kernel.org/r/20210505002735.1684165-3-seanjc@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 include/linux/context_tracking.h |   22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -135,15 +135,20 @@ static __always_inline void context_trac
 		__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();
 }
 
@@ -164,12 +169,17 @@ static __always_inline void guest_enter_
 
 static __always_inline void context_tracking_guest_exit(void) { }
 
+static __always_inline void vtime_account_guest_exit(void)
+{
+	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_kernel(current);
-	current->flags &= ~PF_VCPU;
+	vtime_account_guest_exit();
 	instrumentation_end();
 }
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */