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cpufreq: intel_pstate: Fix unchecked HWP MSR access

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Fix unchecked MSR access error for processors with no HWP support. On
such processors, maximum frequency can be changed by the system firmware
using ACPI event ACPI_PROCESSOR_NOTIFY_HIGEST_PERF_CHANGED. This results
in accessing HWP MSR 0x771.

Call Trace:
	<TASK>
	generic_exec_single+0x58/0x120
	smp_call_function_single+0xbf/0x110
	rdmsrl_on_cpu+0x46/0x60
	intel_pstate_get_hwp_cap+0x1b/0x70
	intel_pstate_update_limits+0x2a/0x60
	acpi_processor_notify+0xb7/0x140
	acpi_ev_notify_dispatch+0x3b/0x60

HWP MSR 0x771 can be only read on a CPU which supports HWP and enabled.
Hence intel_pstate_get_hwp_cap() can only be called when hwp_active is
true.

Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Closes: https://lore.kernel.org/linux-pm/20240529155740.Hq2Hw7be@linutronix.de/
Fixes: e8217b4bec ("cpufreq: intel_pstate: Update the maximum CPU frequency consistently")
Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Srinivas Pandruvada 2024-05-31 16:00:04 -07:00 committed by Rafael J. Wysocki
parent e4731baaf2
commit 1e24c31351
1 changed files with 2 additions and 1 deletions
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3
drivers/cpufreq/intel_pstate.c
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@ -1153,7 +1153,8 @@ static void intel_pstate_update_policies(void)
static void __intel_pstate_update_max_freq(struct cpudata *cpudata,
struct cpufreq_policy *policy)
{
intel_pstate_get_hwp_cap(cpudata);
if (hwp_active)
intel_pstate_get_hwp_cap(cpudata);
policy->cpuinfo.max_freq = READ_ONCE(global.no_turbo) ?
cpudata->pstate.max_freq : cpudata->pstate.turbo_freq;