Comment 0 for bug 1688164

[Impact]
Userspace reads of CNTVCT_EL0 are broken on HiSilicon D05 systems, which breaks some applications such as OpenMPI.

[Test Case]
#include <sys/times.h>
#include <stdio.h>

int main(int argc, char *argv[])
{
   unsigned int freq;
   __asm__ __volatile__ ("mrs %0, CNTFRQ_EL0" : "=r" (freq));
   printf("freq %d\n",freq);
    return (int)freq;
}

==================================
gcc test.c test
./test

This will report an illegal instruction, but should print a frequency value.

[Regression Risk]
The best way we can minimize risk is to verify on both a system that has an errata handler for the timer (D05) and a system that doesn't. We should then be exercising both code paths.