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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@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
This commit is contained in:
Frederic Weisbecker 2013-07-12 19:02:30 +02:00
parent fbb00b568b
commit 2d854e5738
2 changed files with 29 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

58
include/linux/context_tracking.h
View File

@ -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 void guest_enter(void)
{
__guest_enter();
}
static inline void guest_exit(void)
{
__guest_exit();
}
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)
{
/*
* 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;
}
#endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */
#endif

6
kernel/context_tracking.c
View File

@ -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 */
/**