perf event "cache-references" count much more larger in guest than in host

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Dear all

I used cachebench to test if perf works well with collecting Hardware
event count and Hardware cache event count in guest. Most events'
count were correct(almost as same as host), while the count of
cache-refernecs, L1-dcache-load-misses, L1-icache-load-misses,
dTLB-load-misses and iTLB-load-misses were much more larger than in
host. Below is my test result

                                             Host                Guest
cache-refernecs                      417555            1387017
L1-dcache-load-misses           493385            1210518
L1-icache-load-misses            1422020           4497052
dTLB-load-misses                   7182                61347
iTLB-load-misses                    6120                32332

my test command is "perf stat -e <event> -r 5 ./cachebench -b -x 2 -m
10 -d 3 -e 1".
HostOS: kernel 3.7.2  CPU was Xeon 5620, 16 core ,48G mem
GuestOS: only 1 vcpu, 8G mem and used "-cpu host"

Any one has some idea with this big difference between Host and Guest
will be help.

Thanks
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