Messages in this thread | | | Date | Wed, 17 Apr 2024 10:36:59 -0700 | From | Vanshidhar Konda <> | Subject | Re: [PATCH] ACPI: CPPC: Fix bit_offset shift in MASK_VAL macro |
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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) >-- >2.33.8 >
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