2021-04-13 22:54:11

by Sean Christopherson

[permalink] [raw]
Subject: [RFC PATCH 1/7] sched/vtime: Move guest enter/exit vtime accounting to separate helpers

Provide separate helpers for guest enter/exit vtime accounting 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.

Opportunstically delete the vtime_account_kernel() stub now that all
callers are wrapped with CONFIG_VIRT_CPU_ACCOUNTING_NATIVE=y.

No functional change intended.

Suggested-by: Thomas Gleixner <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Signed-off-by: Sean Christopherson <[email protected]>
---
include/linux/context_tracking.h | 17 +++---------
include/linux/vtime.h | 45 +++++++++++++++++++++++++++++---
2 files changed, 45 insertions(+), 17 deletions(-)

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index bceb06498521..58f9a7251d3b 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -102,16 +102,12 @@ extern void context_tracking_init(void);
static inline void context_tracking_init(void) { }
#endif /* CONFIG_CONTEXT_TRACKING_FORCE */

-
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
/* must be called with irqs disabled */
static __always_inline void guest_enter_irqoff(void)
{
instrumentation_begin();
- if (vtime_accounting_enabled_this_cpu())
- vtime_guest_enter(current);
- else
- current->flags |= PF_VCPU;
+ vtime_account_guest_enter();
instrumentation_end();

if (context_tracking_enabled())
@@ -137,10 +133,7 @@ static __always_inline void guest_exit_irqoff(void)
__context_tracking_exit(CONTEXT_GUEST);

instrumentation_begin();
- if (vtime_accounting_enabled_this_cpu())
- vtime_guest_exit(current);
- else
- current->flags &= ~PF_VCPU;
+ vtime_account_guest_exit();
instrumentation_end();
}

@@ -153,8 +146,7 @@ static __always_inline void guest_enter_irqoff(void)
* to flush.
*/
instrumentation_begin();
- vtime_account_kernel(current);
- current->flags |= PF_VCPU;
+ vtime_account_guest_enter();
rcu_virt_note_context_switch(smp_processor_id());
instrumentation_end();
}
@@ -163,8 +155,7 @@ 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 */
diff --git a/include/linux/vtime.h b/include/linux/vtime.h
index 041d6524d144..f30b472a2201 100644
--- a/include/linux/vtime.h
+++ b/include/linux/vtime.h
@@ -3,6 +3,8 @@
#define _LINUX_KERNEL_VTIME_H

#include <linux/context_tracking_state.h>
+#include <linux/sched.h>
+
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
#include <asm/vtime.h>
#endif
@@ -18,6 +20,17 @@ struct task_struct;
static inline bool vtime_accounting_enabled_this_cpu(void) { return true; }
extern void vtime_task_switch(struct task_struct *prev);

+static __always_inline void vtime_account_guest_enter(void)
+{
+ vtime_account_kernel(current);
+ current->flags |= PF_VCPU;
+}
+
+static __always_inline void vtime_account_guest_exit(void)
+{
+
+}
+
#elif defined(CONFIG_VIRT_CPU_ACCOUNTING_GEN)

/*
@@ -49,12 +62,38 @@ static inline void vtime_task_switch(struct task_struct *prev)
vtime_task_switch_generic(prev);
}

+static __always_inline void vtime_account_guest_enter(void)
+{
+ if (vtime_accounting_enabled_this_cpu())
+ vtime_guest_enter(current);
+ else
+ current->flags |= PF_VCPU;
+}
+
+static __always_inline void vtime_account_guest_exit(void)
+{
+ if (vtime_accounting_enabled_this_cpu())
+ vtime_guest_exit(current);
+ else
+ current->flags &= ~PF_VCPU;
+}
+
+
#else /* !CONFIG_VIRT_CPU_ACCOUNTING */

-static inline bool vtime_accounting_enabled_cpu(int cpu) {return false; }
static inline bool vtime_accounting_enabled_this_cpu(void) { return false; }
static inline void vtime_task_switch(struct task_struct *prev) { }

+static __always_inline void vtime_account_guest_enter(void)
+{
+ current->flags |= PF_VCPU;
+}
+
+static __always_inline void vtime_account_guest_exit(void)
+{
+ current->flags &= ~PF_VCPU;
+}
+
#endif

/*
@@ -63,9 +102,7 @@ static inline void vtime_task_switch(struct task_struct *prev) { }
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
extern void vtime_account_kernel(struct task_struct *tsk);
extern void vtime_account_idle(struct task_struct *tsk);
-#else /* !CONFIG_VIRT_CPU_ACCOUNTING */
-static inline void vtime_account_kernel(struct task_struct *tsk) { }
-#endif /* !CONFIG_VIRT_CPU_ACCOUNTING */
+#endif /* CONFIG_VIRT_CPU_ACCOUNTING */

#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
extern void arch_vtime_task_switch(struct task_struct *tsk);
--
2.31.1.295.g9ea45b61b8-goog