2024-04-09 05:25:18

by Jarred White

Subject: [PATCH] ACPI: CPPC: Fix bit_offset shift in MASK_VAL macro

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 <[email protected]>
CC: Vanshidhar Konda <[email protected]>
CC: [email protected] #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

2024-04-16 17:24:47

by Jarred White

Subject: Re: [PATCH] ACPI: CPPC: Fix bit_offset shift in MASK_VAL macro

On 4/8/2024 10:23 PM, 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 <[email protected]>
> CC: Vanshidhar Konda <[email protected]>
> CC: [email protected] #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)

Hi Vanshi,

Could you review please?


Thanks,
Jarred

2024-04-17 17:57:13

by Vanshidhar Konda

Subject: Re: [PATCH] ACPI: CPPC: Fix bit_offset shift in MASK_VAL macro

Looks good to me.

Reviewed-by: Vanshidhar Konda <[email protected]>

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 <[email protected]>
>CC: Vanshidhar Konda <[email protected]>
>CC: [email protected] #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
>

2024-04-22 16:46:13

by Rafael J. Wysocki

Subject: Re: [PATCH] ACPI: CPPC: Fix bit_offset shift in MASK_VAL macro

On Wed, Apr 17, 2024 at 7:37 PM Vanshidhar Konda
<[email protected]> wrote:
>
> Looks good to me.
>
> Reviewed-by: Vanshidhar Konda <[email protected]>
>
> 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 <[email protected]>
> >CC: Vanshidhar Konda <[email protected]>
> >CC: [email protected] #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!