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Date: Wed, 17 Jul 2013 18:44:17 +0200
From: Frederic Weisbecker <fweisbec@...il.com>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Frederic Weisbecker <fweisbec@...il.com>,
Steven Rostedt <rostedt@...dmis.org>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
Ingo Molnar <mingo@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Peter Zijlstra <peterz@...radead.org>,
Borislav Petkov <bp@...en8.de>,
Li Zhong <zhong@...ux.vnet.ibm.com>,
Mike Galbraith <efault@....de>,
Kevin Hilman <khilman@...aro.org>
Subject: [PATCH 04/18] context_tracing: Fix guest accounting with native vtime
1) If context tracking is enabled with native vtime accounting (which
combo is useless except for dev testing), we call vtime_guest_enter()
and vtime_guest_exit() on host <-> guest switches. But those are stubs
in this configurations. As a result, cputime is not correctly flushed
on kvm context switches.
2) If context tracking runs but is disabled on some CPUs, those
CPUs end up calling __guest_enter/__guest_exit which in turn
call vtime_account_system(). We don't want to call this because we
run in tick based accounting for these CPUs.
Refactor the guest_enter/guest_exit code such that all combinations
finally work.
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Li Zhong <zhong@...ux.vnet.ibm.com>
Cc: Mike Galbraith <efault@....de>
Cc: Kevin Hilman <khilman@...aro.org>
---
include/linux/context_tracking.h | 52 ++++++++++++++++----------------------
kernel/context_tracking.c | 6 +++-
2 files changed, 26 insertions(+), 32 deletions(-)
diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index fc09d7b..5984f25 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -20,25 +20,6 @@ struct context_tracking {
} state;
};
-static inline void __guest_enter(void)
-{
- /*
- * This is running in ioctl context so we can avoid
- * the call to vtime_account() with its unnecessary idle check.
- */
- vtime_account_system(current);
- current->flags |= PF_VCPU;
-}
-
-static inline void __guest_exit(void)
-{
- /*
- * This is running in ioctl context so we can avoid
- * the call to vtime_account() with its unnecessary idle check.
- */
- vtime_account_system(current);
- current->flags &= ~PF_VCPU;
-}
#ifdef CONFIG_CONTEXT_TRACKING
DECLARE_PER_CPU(struct context_tracking, context_tracking);
@@ -56,9 +37,6 @@ static inline bool context_tracking_active(void)
extern void user_enter(void);
extern void user_exit(void);
-extern void guest_enter(void);
-extern void guest_exit(void);
-
static inline enum ctx_state exception_enter(void)
{
enum ctx_state prev_ctx;
@@ -81,21 +59,35 @@ extern void context_tracking_task_switch(struct task_struct *prev,
static inline bool context_tracking_in_user(void) { return false; }
static inline void user_enter(void) { }
static inline void user_exit(void) { }
+static inline enum ctx_state exception_enter(void) { return 0; }
+static inline void exception_exit(enum ctx_state prev_ctx) { }
+static inline void context_tracking_task_switch(struct task_struct *prev,
+ struct task_struct *next) { }
+#endif /* !CONFIG_CONTEXT_TRACKING */
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
+extern void guest_enter(void);
+extern void guest_exit(void);
+#else
static inline void guest_enter(void)
{
- __guest_enter();
+ /*
+ * This is running in ioctl context so we can avoid
+ * the call to vtime_account() with its unnecessary idle check.
+ */
+ vtime_account_system(current);
+ current->flags |= PF_VCPU;
}
static inline void guest_exit(void)
{
- __guest_exit();
+ /*
+ * This is running in ioctl context so we can avoid
+ * the call to vtime_account() with its unnecessary idle check.
+ */
+ vtime_account_system(current);
+ current->flags &= ~PF_VCPU;
}
-
-static inline enum ctx_state exception_enter(void) { return 0; }
-static inline void exception_exit(enum ctx_state prev_ctx) { }
-static inline void context_tracking_task_switch(struct task_struct *prev,
- struct task_struct *next) { }
-#endif /* !CONFIG_CONTEXT_TRACKING */
+#endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */
#endif
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 942835c..1f47119 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -141,12 +141,13 @@ void user_exit(void)
local_irq_restore(flags);
}
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
void guest_enter(void)
{
if (vtime_accounting_enabled())
vtime_guest_enter(current);
else
- __guest_enter();
+ current->flags |= PF_VCPU;
}
EXPORT_SYMBOL_GPL(guest_enter);
@@ -155,9 +156,10 @@ void guest_exit(void)
if (vtime_accounting_enabled())
vtime_guest_exit(current);
else
- __guest_exit();
+ current->flags &= ~PF_VCPU;
}
EXPORT_SYMBOL_GPL(guest_exit);
+#endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */
/**
--
1.7.5.4
--
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