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Date:   Tue, 8 Sep 2020 19:31:28 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc:     "Jason A. Donenfeld" <Jason@zx2c4.com>,
        kitsunyan <kitsunyan@airmail.cc>,
        "Brown, Len" <len.brown@intel.com>, x86@kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86/msr: do not warn on writes to OC_MAILBOX
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On Tue, Sep 08, 2020 at 10:10:17AM -0700, Srinivas Pandruvada wrote:
> > > -	if (reg == MSR_IA32_ENERGY_PERF_BIAS)
> > > +	switch (reg) {
> > > +	case MSR_IA32_ENERGY_PERF_BIAS:
> There is already sysfs interface for it.

So someone needs to convert all those to it:

tools/power/cpupower/utils/helpers/msr.c:14:#define MSR_IA32_ENERGY_PERF_BIAS   0x1b0
tools/power/cpupower/utils/helpers/msr.c:84:    ret = read_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &val);
tools/power/cpupower/utils/helpers/msr.c:97:    ret = write_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, val);
tools/power/x86/turbostat/turbostat.8:222:cpu0: MSR_IA32_ENERGY_PERF_BIAS: 0x00000006 (balanced)
tools/power/x86/turbostat/turbostat.c:3652:     if (get_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &msr))
tools/power/x86/turbostat/turbostat.c:3669:     fprintf(outf, "cpu%d: MSR_IA32_ENERGY_PERF_BIAS: 0x%08llx (%s)\n", cpu, msr, epb_string);
tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.8:25:Policy in MSR_IA32_ENERGY_PERF_BIAS (EPB)
tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.8:33:Note that MSR_IA32_ENERGY_PERF_BIAS is defined per CPU,
tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c:84:unsigned int has_epb;        /* MSR_IA32_ENERGY_PERF_BIAS */
tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c:755:            get_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &msr);
tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c:1044:           get_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &msr);
tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c:1045:           put_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, new_epb);

Any takers?

If there are none, it could be made into a small kernelnewbies
project...

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette