Re: [PATCH v14 11/11] selftests: kvm/x86: add test for pmu msr MSR_IA32_PERF_CAPABILITIES

[Paolo Bonzini]

On 01/02/21 07:01, Like Xu wrote:
> +uint64_t rdmsr_on_cpu(uint32_t reg)
> +{
> +	uint64_t data;
> +	int fd;
> +	char msr_file[64];
> +
> +	sprintf(msr_file, "/dev/cpu/%d/msr", 0);
> +	fd = open(msr_file, O_RDONLY);
> +	if (fd < 0)
> +		exit(KSFT_SKIP);
> +
> +	if (pread(fd, &data, sizeof(data), reg) != sizeof(data))
> +		exit(KSFT_SKIP);
> +
> +	close(fd);
> +	return data;
> +}

In order to allow running as non-root, it's better to use the 
KVM_GET_MSRS ioctl on the /dev/kvm file descriptor.

The tests pass, but please take a look at the kvm/queue branch to see if 
everything is ok.

Paolo