[PATCH] KVM: add VM-exit profiling

This adds the profile=kvm boot option, which enables KVM to profile VM
exits.

Use: "readprofile -m ./System.map | sort -n" to see the resulting
output:

   [...]
   18246 serial_out                               148.3415
   18945 native_flush_tlb                         378.9000
   23618 serial_in                                212.7748
   29279 __spin_unlock_irq                        622.9574
   43447 native_apic_write                        2068.9048
   52702 enable_8259A_irq                         742.2817
   54250 vgacon_scroll                             89.3740
   67394 ide_inb                                  6126.7273
   79514 copy_page_range                           98.1654
   84868 do_wp_page                                86.6000
  140266 pit_read                                 783.6089
  151436 ide_outb                                 25239.3333
  152668 native_io_delay                          21809.7143
  174783 mask_and_ack_8259A                       783.7803
  362404 native_set_pte_at                        36240.4000
 1688747 total                                      0.5009

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Avi Kivity <avi@qumranet.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c
index ccc06b1b91b5..714f6a7841cd 100644
--- a/drivers/kvm/svm.c
+++ b/drivers/kvm/svm.c
@@ -17,6 +17,7 @@
 #include <linux/module.h>
 #include <linux/vmalloc.h>
 #include <linux/highmem.h>
+#include <linux/profile.h>
 #include <asm/desc.h>
 
 #include "kvm_svm.h"
@@ -1558,6 +1559,13 @@ again:
 
         reload_tss(vcpu);
 
+        /*
+         * Profile KVM exit RIPs:
+         */
+        if (unlikely(prof_on == KVM_PROFILING))
+                profile_hit(KVM_PROFILING,
+                        (void *)(unsigned long)vcpu->svm->vmcb->save.rip);
+
         stgi();
 
         kvm_reput_irq(vcpu);