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authorPaolo Bonzini <pbonzini@redhat.com>2015-10-28 02:39:56 +0100
committerPaolo Bonzini <pbonzini@redhat.com>2015-11-10 12:06:23 +0100
commitd0e536d89395ecd8ab78fe999dc4d6f5d140ce46 (patch)
treebac5690350e345061db0206bbbe91dbeeb6ebdad /include
parentf70cd6b07e629f367bb9b1ac9d0e3e669eb325c0 (diff)
downloadlinux-d0e536d89395ecd8ab78fe999dc4d6f5d140ce46.tar.bz2
context_tracking: avoid irq_save/irq_restore on guest entry and exit
guest_enter and guest_exit must be called with interrupts disabled, since they take the vtime_seqlock with write_seq{lock,unlock}. Therefore, it is not necessary to check for exceptions, nor to save/restore the IRQ state, when context tracking functions are called by guest_enter and guest_exit. Split the body of context_tracking_entry and context_tracking_exit out to __-prefixed functions, and use them from KVM. Rik van Riel has measured this to speed up a tight vmentry/vmexit loop by about 2%. Cc: Andy Lutomirski <luto@kernel.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Paul McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Rik van Riel <riel@redhat.com> Tested-by: Rik van Riel <riel@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'include')
-rw-r--r--include/linux/context_tracking.h8
1 files changed, 6 insertions, 2 deletions
diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index 6ef136ff0897..68b575afe5f5 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -10,6 +10,10 @@
#ifdef CONFIG_CONTEXT_TRACKING
extern void context_tracking_cpu_set(int cpu);
+/* Called with interrupts disabled. */
+extern void __context_tracking_enter(enum ctx_state state);
+extern void __context_tracking_exit(enum ctx_state state);
+
extern void context_tracking_enter(enum ctx_state state);
extern void context_tracking_exit(enum ctx_state state);
extern void context_tracking_user_enter(void);
@@ -88,13 +92,13 @@ static inline void guest_enter(void)
current->flags |= PF_VCPU;
if (context_tracking_is_enabled())
- context_tracking_enter(CONTEXT_GUEST);
+ __context_tracking_enter(CONTEXT_GUEST);
}
static inline void guest_exit(void)
{
if (context_tracking_is_enabled())
- context_tracking_exit(CONTEXT_GUEST);
+ __context_tracking_exit(CONTEXT_GUEST);
if (vtime_accounting_enabled())
vtime_guest_exit(current);