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authorRik van Riel <riel@redhat.com>2015-02-10 23:27:54 +0300
committerFrederic Weisbecker <fweisbec@gmail.com>2015-03-09 17:43:03 +0300
commit126a6a542446f1a49b9f3c69237c87df3eb4e6e1 (patch)
tree8c88aa922f1cd1d313025b61dca911b20c5614b9
parentefc1e2c9bcbab73797d7bc214014cb916d6a8eb5 (diff)
downloadlinux-126a6a542446f1a49b9f3c69237c87df3eb4e6e1.tar.xz
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 <paulmck@linux.vnet.ibm.com> Signed-off-by: Rik van Riel <riel@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Will deacon <will.deacon@arm.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
-rw-r--r--include/linux/context_tracking.h6
-rw-r--r--include/linux/context_tracking_state.h1
-rw-r--r--include/linux/kvm_host.h3
3 files changed, 9 insertions, 1 deletions
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)