KVM: ppc: Implement in-kernel exit timing statistics

Existing KVM statistics are either just counters (kvm_stat) reported for
KVM generally or trace based aproaches like kvm_trace.
For KVM on powerpc we had the need to track the timings of the different exit
types. While this could be achieved parsing data created with a kvm_trace
extension this adds too much overhead (at least on embedded PowerPC) slowing
down the workloads we wanted to measure.

Therefore this patch adds a in-kernel exit timing statistic to the powerpc kvm
code. These statistic is available per vm&vcpu under the kvm debugfs directory.
As this statistic is low, but still some overhead it can be enabled via a
.config entry and should be off by default.

Since this patch touched all powerpc kvm_stat code anyway this code is now
merged and simplified together with the exit timing statistic code (still
working with exit timing disabled in .config).

Signed-off-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index ba39526d3201..9937fe44555f 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -383,5 +383,16 @@ int main(void)
         DEFINE(PTE_T_LOG2, PTE_T_LOG2);
 #endif
 
+#ifdef CONFIG_KVM_EXIT_TIMING
+        DEFINE(VCPU_TIMING_EXIT_TBU, offsetof(struct kvm_vcpu,
+                                                arch.timing_exit.tv32.tbu));
+        DEFINE(VCPU_TIMING_EXIT_TBL, offsetof(struct kvm_vcpu,
+                                                arch.timing_exit.tv32.tbl));
+        DEFINE(VCPU_TIMING_LAST_ENTER_TBU, offsetof(struct kvm_vcpu,
+                                        arch.timing_last_enter.tv32.tbu));
+        DEFINE(VCPU_TIMING_LAST_ENTER_TBL, offsetof(struct kvm_vcpu,
+                                        arch.timing_last_enter.tv32.tbl));
+#endif
+
         return 0;
 }