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

commit 05d92ee782eeb7b939bdd0189e6efcab9195bf95 upstream

Commit 2f4a4d63a193 ("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: 2f4a4d63a193 ("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>
Signed-off-by: Easwar Hariharan <eahariha@linux.microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 408b1fda5702d578042f9b3f1430a0d38c9c4b5c..6aa456cda0ed964917b5e4a428014246fe8359bb 100644 (file)
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -165,8 +165,8 @@ 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)