On Wed, Apr 17, 2024 at 7:37 PM Vanshidhar Konda vanshikonda@os.amperecomputing.com wrote:

Looks good to me.

Reviewed-by: Vanshidhar Konda vanshikonda@os.amperecomputing.com

On Mon, Apr 08, 2024 at 10:23:09PM -0700, Jarred White wrote:

...

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: Vanshidhar Konda vanshikonda@os.amperecomputing.com CC: stable@vger.kernel.org #5.15+

---

drivers/acpi/cppc_acpi.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c index 4bfbe55553f4..00a30ca35e78 100644 --- a/drivers/acpi/cppc_acpi.c +++ b/drivers/acpi/cppc_acpi.c @@ -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) --

Applied as 6.9-rc material, thanks!