1e24c31351
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: e8217b4bece3 ("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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.