Where is the cntfrq_el0 register set for arm64 virt machine?

[Chan Kim]

Hi,

It may not be important but I'm trying to make the linux boot log the same
for qemu direct kernel loading and loading by u-boot.
In armv8 the cntfrq_el0 register is supposed to be written with the system
counter frequency. The armv8 manual says it doesn't affect the hardware
operation and it's just for S/W to know the frequency. U-boot program writes
to that register with COUNTER_FREQUENCY value, when it's defined. In current
armv8 virt machine, it's read as 62.5MHz but I coulnd't find where in the
source the value is written. Where should I change to value in the qemu
source? 
Thank you.

Chan Kim