From c467ea763fd5d8795b7d1b5a78eb94b6ad8f66ad Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Wed, 4 Mar 2015 18:06:33 +0100 Subject: context_tracking: Rename context symbols to prepare for transition state Current context tracking symbols are designed to express living state. As such they are prefixed with "IN_": IN_USER, IN_KERNEL. Now we are going to use these symbols to also express state transitions such as context_tracking_enter(IN_USER) or context_tracking_exit(IN_USER). But while the "IN_" prefix works well to express entering a context, it's confusing to depict a context exit: context_tracking_exit(IN_USER) could mean two things: 1) We are exiting the current context to enter user context. 2) We are exiting the user context We want 2) but the reviewer may be confused and understand 1) So lets disambiguate these symbols and rename them to CONTEXT_USER and CONTEXT_KERNEL. Acked-by: Rik van Riel Cc: Paul E. McKenney Cc: Andy Lutomirski Cc: Will deacon Cc: Marcelo Tosatti Cc: Christian Borntraeger Cc: Luiz Capitulino Cc: Paolo Bonzini Signed-off-by: Frederic Weisbecker --- include/linux/context_tracking_state.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'include/linux/context_tracking_state.h') diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h index 97a81225d037..8076f875c324 100644 --- a/include/linux/context_tracking_state.h +++ b/include/linux/context_tracking_state.h @@ -13,8 +13,8 @@ struct context_tracking { */ bool active; enum ctx_state { - IN_KERNEL = 0, - IN_USER, + CONTEXT_KERNEL = 0, + CONTEXT_USER, } state; }; @@ -34,7 +34,7 @@ static inline bool context_tracking_cpu_is_enabled(void) static inline bool context_tracking_in_user(void) { - return __this_cpu_read(context_tracking.state) == IN_USER; + return __this_cpu_read(context_tracking.state) == CONTEXT_USER; } #else static inline bool context_tracking_in_user(void) { return false; } -- cgit v1.2.3 From a3a9c7dff25791f3a1041aa96e770af662d99a35 Mon Sep 17 00:00:00 2001 From: Rik van Riel Date: Tue, 10 Feb 2015 15:27:51 -0500 Subject: context_tracking: Add stub context_tracking_is_enabled With code elsewhere doing something conditional on whether or not context tracking is enabled, we want a stub function that tells us context tracking is not enabled, when CONFIG_CONTEXT_TRACKING is not set. Reviewed-by: Paul E. McKenney Signed-off-by: Rik van Riel Cc: Paul E. McKenney Cc: Andy Lutomirski Cc: Will deacon Cc: Marcelo Tosatti Cc: Christian Borntraeger Cc: Luiz Capitulino Cc: Paolo Bonzini Signed-off-by: Frederic Weisbecker --- include/linux/context_tracking_state.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/context_tracking_state.h') diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h index 8076f875c324..ad4458588b47 100644 --- a/include/linux/context_tracking_state.h +++ b/include/linux/context_tracking_state.h @@ -39,6 +39,8 @@ static inline bool context_tracking_in_user(void) #else static inline bool context_tracking_in_user(void) { return false; } static inline bool context_tracking_active(void) { return false; } +static inline bool context_tracking_is_enabled(void) { return false; } +static inline bool context_tracking_cpu_is_enabled(void) { return false; } #endif /* CONFIG_CONTEXT_TRACKING */ #endif -- cgit v1.2.3 From 126a6a542446f1a49b9f3c69237c87df3eb4e6e1 Mon Sep 17 00:00:00 2001 From: Rik van Riel Date: Tue, 10 Feb 2015 15:27:54 -0500 Subject: kvm,rcu,nohz: use RCU extended quiescent state when running KVM guest The host kernel is not doing anything while the CPU is executing a KVM guest VCPU, so it can be marked as being in an extended quiescent state, identical to that used when running user space code. The only exception to that rule is when the host handles an interrupt, which is already handled by the irq code, which calls rcu_irq_enter and rcu_irq_exit. The guest_enter and guest_exit functions already switch vtime accounting independent of context tracking. Leave those calls where they are, instead of moving them into the context tracking code. Reviewed-by: Paul E. McKenney Signed-off-by: Rik van Riel Cc: Paul E. McKenney Cc: Andy Lutomirski Cc: Will deacon Cc: Marcelo Tosatti Cc: Christian Borntraeger Cc: Luiz Capitulino Cc: Paolo Bonzini Signed-off-by: Frederic Weisbecker --- include/linux/context_tracking.h | 6 ++++++ include/linux/context_tracking_state.h | 1 + include/linux/kvm_host.h | 3 ++- 3 files changed, 9 insertions(+), 1 deletion(-) (limited to 'include/linux/context_tracking_state.h') diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h index 7f1810a3b5a4..2821838256b4 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -81,10 +81,16 @@ static inline void guest_enter(void) vtime_guest_enter(current); else current->flags |= PF_VCPU; + + if (context_tracking_is_enabled()) + context_tracking_enter(CONTEXT_GUEST); } static inline void guest_exit(void) { + if (context_tracking_is_enabled()) + context_tracking_exit(CONTEXT_GUEST); + if (vtime_accounting_enabled()) vtime_guest_exit(current); else diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h index ad4458588b47..6b7b96a32b75 100644 --- a/include/linux/context_tracking_state.h +++ b/include/linux/context_tracking_state.h @@ -15,6 +15,7 @@ struct context_tracking { enum ctx_state { CONTEXT_KERNEL = 0, CONTEXT_USER, + CONTEXT_GUEST, } state; }; diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index d12b2104d19b..cc8c61c5459c 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -766,7 +766,8 @@ static inline void kvm_guest_enter(void) * one time slice). Lets treat guest mode as quiescent state, just like * we do with user-mode execution. */ - rcu_virt_note_context_switch(smp_processor_id()); + if (!context_tracking_cpu_is_enabled()) + rcu_virt_note_context_switch(smp_processor_id()); } static inline void kvm_guest_exit(void) -- cgit v1.2.3