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cpupower: mperf_monitor: Update cpupower to use the RDPRU instruction 

AMD Zen 2 introduces the RDPRU instruction which can be used to access some
processor registers which are typically only accessible in privilege level
0. ECX specifies the register to read and EDX:EAX will contain the value read.

ECX: 0 - Register MPERF
     1 - Register APERF

This has the added advantage of not having to use the msr module, since the
userspace to kernel transitions which occur during each read_msr() might
cause APERF and MPERF to go out of sync.

Signed-off-by: Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>
Acked-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
This commit is contained in:
Janakarajan Natarajan 2019-11-05 17:16:55 +00:00 committed by Shuah Khan
parent 7adafe541f
commit 6af2ed53f0
3 changed files with 25 additions and 0 deletions
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4
tools/power/cpupower/utils/helpers/cpuid.c
View File

@ -131,6 +131,10 @@ out:
if (ext_cpuid_level >= 0x80000007 &&
(cpuid_edx(0x80000007) & (1 << 9)))
cpu_info->caps |= CPUPOWER_CAP_AMD_CBP;
if (ext_cpuid_level >= 0x80000008 &&
cpuid_ebx(0x80000008) & (1 << 4))
cpu_info->caps |= CPUPOWER_CAP_AMD_RDPRU;
}
if (cpu_info->vendor == X86_VENDOR_INTEL) {

1
tools/power/cpupower/utils/helpers/helpers.h
View File

@ -69,6 +69,7 @@ enum cpupower_cpu_vendor {X86_VENDOR_UNKNOWN = 0, X86_VENDOR_INTEL,
#define CPUPOWER_CAP_HAS_TURBO_RATIO 0x00000010
#define CPUPOWER_CAP_IS_SNB 0x00000020
#define CPUPOWER_CAP_INTEL_IDA 0x00000040
#define CPUPOWER_CAP_AMD_RDPRU 0x00000080
#define CPUPOWER_AMD_CPBDIS 0x02000000

20
tools/power/cpupower/utils/idle_monitor/mperf_monitor.c
View File

@ -19,6 +19,10 @@
#define MSR_APERF 0xE8
#define MSR_MPERF 0xE7
#define RDPRU ".byte 0x0f, 0x01, 0xfd"
#define RDPRU_ECX_MPERF 0
#define RDPRU_ECX_APERF 1
#define MSR_TSC 0x10
#define MSR_AMD_HWCR 0xc0010015
@ -89,6 +93,8 @@ static int mperf_get_tsc(unsigned long long *tsc)
static int get_aperf_mperf(int cpu, unsigned long long *aval,
unsigned long long *mval)
{
unsigned long low_a, high_a;
unsigned long low_m, high_m;
int ret;
/*
@ -101,6 +107,20 @@ static int get_aperf_mperf(int cpu, unsigned long long *aval,
return 1;
}
if (cpupower_cpu_info.caps & CPUPOWER_CAP_AMD_RDPRU) {
asm volatile(RDPRU
: "=a" (low_a), "=d" (high_a)
: "c" (RDPRU_ECX_APERF));
asm volatile(RDPRU
: "=a" (low_m), "=d" (high_m)
: "c" (RDPRU_ECX_MPERF));
*aval = ((low_a) | (high_a) << 32);
*mval = ((low_m) | (high_m) << 32);
return 0;
}
ret = read_msr(cpu, MSR_APERF, aval);
ret |= read_msr(cpu, MSR_MPERF, mval);