linux-kernel - [PATCH] move kvm_guest_exit() after local_irq

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Message-Id: <11927135412363-git-send-email-Laurent.Vivier@bull.net>
Date:	Thu, 18 Oct 2007 15:19:01 +0200
From:	Laurent Vivier <Laurent.Vivier@...l.net>
To:	mingo@...e.hu
Cc:	linux-kernel@...r.kernel.org, avi@...ranet.com,
	borntraeger@...ibm.com, kvm-devel@...ts.sourceforge.net,
	Laurent Vivier <Laurent.Vivier@...l.net>
Subject: [PATCH] move kvm_guest_exit() after local_irq_enable()

According comments from Avi, we can clear PF_VCPU in kvm_guest_exit if we move
it after local_irq_enable().

http://lkml.org/lkml/2007/10/15/114

To simplify s390 port, we don't clear it in account_system_time().

http://lkml.org/lkml/2007/10/15/183

---
 drivers/kvm/kvm_main.c |    5 ++++-
 kernel/sched.c         |    1 -
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 87275be..b9cd1f0 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -2194,12 +2194,15 @@ again:
 
 	kvm_x86_ops->run(vcpu, kvm_run);
 
-	kvm_guest_exit();
 	vcpu->guest_mode = 0;
 	local_irq_enable();
 
 	++vcpu->stat.exits;
 
+	barrier();
+
+	kvm_guest_exit();
+
 	preempt_enable();
 
 	/*
diff --git a/kernel/sched.c b/kernel/sched.c
index b27ab3e..57fac22 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3315,7 +3315,6 @@ void account_system_time(struct task_struct *p, int hardirq_offset,
 #ifdef CONFIG_GUEST_ACCOUNTING
 	if (p->flags & PF_VCPU) {
 		account_guest_time(p, cputime);
-		p->flags &= ~PF_VCPU;
 		return;
 	}
 #endif
-- 
1.5.2.4

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