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ACPI: CPPC: Fix bit_offset shift in MASK_VAL() macro 

Commit 2f4a4d63a1 ("ACPI: CPPC: Use access_width over bit_width for
system memory accesses") neglected to properly wrap the bit_offset shift
when it comes to applying the mask. This may cause incorrect values to be
read and may cause the cpufreq module not be loaded.

[   11.059751] cpu_capacity: CPU0 missing/invalid highest performance.
[   11.066005] cpu_capacity: partial information: fallback to 1024 for all CPUs

Also, corrected the bitmask generation in GENMASK (extra bit being added).

Fixes: 2f4a4d63a1 ("ACPI: CPPC: Use access_width over bit_width for system memory accesses")
Signed-off-by: Jarred White <jarredwhite@linux.microsoft.com>
Cc: 5.15+ <stable@vger.kernel.org> # 5.15+
Reviewed-by: Vanshidhar Konda <vanshikonda@os.amperecomputing.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Jarred White 2024-04-08 22:23:09 -07:00 committed by Rafael J. Wysocki
parent ed30a4a51b
commit 05d92ee782
1 changed files with 2 additions and 2 deletions
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4
drivers/acpi/cppc_acpi.c
View File

@ -170,8 +170,8 @@ show_cppc_data(cppc_get_perf_ctrs, cppc_perf_fb_ctrs, wraparound_time);
#define GET_BIT_WIDTH(reg) ((reg)->access_width ? (8 << ((reg)->access_width - 1)) : (reg)->bit_width)
/* Shift and apply the mask for CPC reads/writes */
#define MASK_VAL(reg, val) ((val) >> ((reg)->bit_offset & \
GENMASK(((reg)->bit_width), 0)))
#define MASK_VAL(reg, val) (((val) >> (reg)->bit_offset) & \
GENMASK(((reg)->bit_width) - 1, 0))
static ssize_t show_feedback_ctrs(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)