From: Arnd Bergmann <[email protected]>
The new epp support causes warnings about three separate
but related bugs:
1) failing before allocation should just return an error:
drivers/cpufreq/amd-pstate.c:951:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
if (!dev)
^~~~
drivers/cpufreq/amd-pstate.c:1018:9: note: uninitialized use occurs here
return ret;
^~~
2) wrong variable to store return code:
drivers/cpufreq/amd-pstate.c:963:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
if (rc)
^~
drivers/cpufreq/amd-pstate.c:1019:9: note: uninitialized use occurs here
return ret;
^~~
drivers/cpufreq/amd-pstate.c:963:2: note: remove the 'if' if its condition is always false
if (rc)
^~~~~~~
3) calling amd_pstate_set_epp() in cleanup path after determining
that it should not be called:
drivers/cpufreq/amd-pstate.c:1055:6: error: variable 'epp' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
if (cpudata->epp_policy == cpudata->policy)
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/cpufreq/amd-pstate.c:1080:30: note: uninitialized use occurs here
amd_pstate_set_epp(cpudata, epp);
^~~
All three are trivial to fix, but most likely there are additional bugs
in this function when the error handling was not really tested.
Fixes: ffa5096a7c33 ("cpufreq: amd-pstate: implement Pstate EPP support for the AMD processors")
Signed-off-by: Arnd Bergmann <[email protected]>
---
drivers/cpufreq/amd-pstate.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 168a28bed6ee..847f5f31396d 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -940,7 +940,6 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
struct amd_cpudata *cpudata;
struct device *dev;
- int rc;
u64 value;
/*
@@ -950,7 +949,7 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
amd_perf_ctl_reset(policy->cpu);
dev = get_cpu_device(policy->cpu);
if (!dev)
- goto free_cpudata1;
+ return -ENODEV;
cpudata = kzalloc(sizeof(*cpudata), GFP_KERNEL);
if (!cpudata)
@@ -959,8 +958,8 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
cpudata->cpu = policy->cpu;
cpudata->epp_policy = 0;
- rc = amd_pstate_init_perf(cpudata);
- if (rc)
+ ret = amd_pstate_init_perf(cpudata);
+ if (ret)
goto free_cpudata1;
min_freq = amd_get_min_freq(cpudata);
@@ -1076,9 +1075,9 @@ static void amd_pstate_epp_init(unsigned int cpu)
value |= (u64)epp << 24;
}
+ amd_pstate_set_epp(cpudata, epp);
skip_epp:
WRITE_ONCE(cpudata->cppc_req_cached, value);
- amd_pstate_set_epp(cpudata, epp);
cpufreq_cpu_put(policy);
}
--
2.39.1
On 07 Feb 17:12, Arnd Bergmann wrote:
> From: Arnd Bergmann <[email protected]>
>
> The new epp support causes warnings about three separate
> but related bugs:
>
> 1) failing before allocation should just return an error:
>
> drivers/cpufreq/amd-pstate.c:951:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> if (!dev)
> ^~~~
> drivers/cpufreq/amd-pstate.c:1018:9: note: uninitialized use occurs here
> return ret;
> ^~~
>
> 2) wrong variable to store return code:
>
> drivers/cpufreq/amd-pstate.c:963:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> if (rc)
> ^~
> drivers/cpufreq/amd-pstate.c:1019:9: note: uninitialized use occurs here
> return ret;
> ^~~
> drivers/cpufreq/amd-pstate.c:963:2: note: remove the 'if' if its condition is always false
> if (rc)
> ^~~~~~~
>
> 3) calling amd_pstate_set_epp() in cleanup path after determining
> that it should not be called:
>
> drivers/cpufreq/amd-pstate.c:1055:6: error: variable 'epp' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> if (cpudata->epp_policy == cpudata->policy)
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/cpufreq/amd-pstate.c:1080:30: note: uninitialized use occurs here
> amd_pstate_set_epp(cpudata, epp);
> ^~~
>
> All three are trivial to fix, but most likely there are additional bugs
> in this function when the error handling was not really tested.
>
> Fixes: ffa5096a7c33 ("cpufreq: amd-pstate: implement Pstate EPP support for the AMD processors")
> Signed-off-by: Arnd Bergmann <[email protected]>
> ---
> drivers/cpufreq/amd-pstate.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 168a28bed6ee..847f5f31396d 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -940,7 +940,6 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
> struct amd_cpudata *cpudata;
> struct device *dev;
> - int rc;
> u64 value;
>
> /*
> @@ -950,7 +949,7 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> amd_perf_ctl_reset(policy->cpu);
> dev = get_cpu_device(policy->cpu);
> if (!dev)
> - goto free_cpudata1;
> + return -ENODEV;
>
> cpudata = kzalloc(sizeof(*cpudata), GFP_KERNEL);
> if (!cpudata)
> @@ -959,8 +958,8 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> cpudata->cpu = policy->cpu;
> cpudata->epp_policy = 0;
>
> - rc = amd_pstate_init_perf(cpudata);
> - if (rc)
> + ret = amd_pstate_init_perf(cpudata);
> + if (ret)
> goto free_cpudata1;
>
> min_freq = amd_get_min_freq(cpudata);
> @@ -1076,9 +1075,9 @@ static void amd_pstate_epp_init(unsigned int cpu)
> value |= (u64)epp << 24;
> }
>
> + amd_pstate_set_epp(cpudata, epp);
> skip_epp:
> WRITE_ONCE(cpudata->cppc_req_cached, value);
> - amd_pstate_set_epp(cpudata, epp);
> cpufreq_cpu_put(policy);
> }
>
Tested this on AMD Milan (Zen 3) system.
Tested-by: Wyes Karny <[email protected]>
> --
> 2.39.1
>
[AMD Official Use Only - General]
Hi Arnd,
> -----Original Message-----
> From: Arnd Bergmann <[email protected]>
> Sent: Wednesday, February 8, 2023 12:13 AM
> To: Huang, Ray <[email protected]>; Rafael J. Wysocki
> <[email protected]>; Viresh Kumar <[email protected]>; Karny, Wyes
> <[email protected]>; Yuan, Perry <[email protected]>; Limonciello,
> Mario <[email protected]>
> Cc: Arnd Bergmann <[email protected]>; Yuan, Perry <[email protected]>;
> Limonciello, Mario <[email protected]>; Jinzhou Su
> <[email protected]>; Meng, Li (Jassmine) <[email protected]>; linux-
> [email protected]; [email protected]
> Subject: [PATCH] cpufreq: amd-pstate: avoid uninitialized variable use
>
> From: Arnd Bergmann <[email protected]>
>
> The new epp support causes warnings about three separate but related bugs:
>
> 1) failing before allocation should just return an error:
>
> drivers/cpufreq/amd-pstate.c:951:6: error: variable 'ret' is used uninitialized
> whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> if (!dev)
> ^~~~
> drivers/cpufreq/amd-pstate.c:1018:9: note: uninitialized use occurs here
> return ret;
> ^~~
>
> 2) wrong variable to store return code:
>
> drivers/cpufreq/amd-pstate.c:963:6: error: variable 'ret' is used uninitialized
> whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> if (rc)
> ^~
> drivers/cpufreq/amd-pstate.c:1019:9: note: uninitialized use occurs here
> return ret;
> ^~~
> drivers/cpufreq/amd-pstate.c:963:2: note: remove the 'if' if its condition is
> always false
> if (rc)
> ^~~~~~~
>
> 3) calling amd_pstate_set_epp() in cleanup path after determining that it
> should not be called:
>
> drivers/cpufreq/amd-pstate.c:1055:6: error: variable 'epp' is used
> uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-
> uninitialized]
> if (cpudata->epp_policy == cpudata->policy)
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/cpufreq/amd-pstate.c:1080:30: note: uninitialized use occurs here
> amd_pstate_set_epp(cpudata, epp);
> ^~~
>
> All three are trivial to fix, but most likely there are additional bugs in this
> function when the error handling was not really tested.
>
> Fixes: ffa5096a7c33 ("cpufreq: amd-pstate: implement Pstate EPP support
> for the AMD processors")
> Signed-off-by: Arnd Bergmann <[email protected]>
> ---
> drivers/cpufreq/amd-pstate.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 168a28bed6ee..847f5f31396d 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -940,7 +940,6 @@ static int amd_pstate_epp_cpu_init(struct
> cpufreq_policy *policy)
> int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
> struct amd_cpudata *cpudata;
> struct device *dev;
> - int rc;
> u64 value;
>
> /*
> @@ -950,7 +949,7 @@ static int amd_pstate_epp_cpu_init(struct
> cpufreq_policy *policy)
> amd_perf_ctl_reset(policy->cpu);
> dev = get_cpu_device(policy->cpu);
> if (!dev)
> - goto free_cpudata1;
> + return -ENODEV;
>
> cpudata = kzalloc(sizeof(*cpudata), GFP_KERNEL);
> if (!cpudata)
> @@ -959,8 +958,8 @@ static int amd_pstate_epp_cpu_init(struct
> cpufreq_policy *policy)
> cpudata->cpu = policy->cpu;
> cpudata->epp_policy = 0;
>
> - rc = amd_pstate_init_perf(cpudata);
> - if (rc)
> + ret = amd_pstate_init_perf(cpudata);
> + if (ret)
> goto free_cpudata1;
>
> min_freq = amd_get_min_freq(cpudata);
> @@ -1076,9 +1075,9 @@ static void amd_pstate_epp_init(unsigned int cpu)
> value |= (u64)epp << 24;
> }
>
> + amd_pstate_set_epp(cpudata, epp);
> skip_epp:
> WRITE_ONCE(cpudata->cppc_req_cached, value);
> - amd_pstate_set_epp(cpudata, epp);
> cpufreq_cpu_put(policy);
> }
>
> --
> 2.39.1
Thanks for your quick fix patch.
Reviewed-by: Yuan Perry <[email protected]>
On Wed, Feb 08, 2023 at 12:12:51AM +0800, Arnd Bergmann wrote:
> From: Arnd Bergmann <[email protected]>
>
> The new epp support causes warnings about three separate
> but related bugs:
>
> 1) failing before allocation should just return an error:
>
> drivers/cpufreq/amd-pstate.c:951:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> if (!dev)
> ^~~~
> drivers/cpufreq/amd-pstate.c:1018:9: note: uninitialized use occurs here
> return ret;
> ^~~
>
> 2) wrong variable to store return code:
>
> drivers/cpufreq/amd-pstate.c:963:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> if (rc)
> ^~
> drivers/cpufreq/amd-pstate.c:1019:9: note: uninitialized use occurs here
> return ret;
> ^~~
> drivers/cpufreq/amd-pstate.c:963:2: note: remove the 'if' if its condition is always false
> if (rc)
> ^~~~~~~
>
> 3) calling amd_pstate_set_epp() in cleanup path after determining
> that it should not be called:
>
> drivers/cpufreq/amd-pstate.c:1055:6: error: variable 'epp' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> if (cpudata->epp_policy == cpudata->policy)
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/cpufreq/amd-pstate.c:1080:30: note: uninitialized use occurs here
> amd_pstate_set_epp(cpudata, epp);
> ^~~
>
> All three are trivial to fix, but most likely there are additional bugs
> in this function when the error handling was not really tested.
>
> Fixes: ffa5096a7c33 ("cpufreq: amd-pstate: implement Pstate EPP support for the AMD processors")
> Signed-off-by: Arnd Bergmann <[email protected]>
Thanks!
Acked-by: Huang Rui <[email protected]>
> ---
> drivers/cpufreq/amd-pstate.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 168a28bed6ee..847f5f31396d 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -940,7 +940,6 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
> struct amd_cpudata *cpudata;
> struct device *dev;
> - int rc;
> u64 value;
>
> /*
> @@ -950,7 +949,7 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> amd_perf_ctl_reset(policy->cpu);
> dev = get_cpu_device(policy->cpu);
> if (!dev)
> - goto free_cpudata1;
> + return -ENODEV;
>
> cpudata = kzalloc(sizeof(*cpudata), GFP_KERNEL);
> if (!cpudata)
> @@ -959,8 +958,8 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> cpudata->cpu = policy->cpu;
> cpudata->epp_policy = 0;
>
> - rc = amd_pstate_init_perf(cpudata);
> - if (rc)
> + ret = amd_pstate_init_perf(cpudata);
> + if (ret)
> goto free_cpudata1;
>
> min_freq = amd_get_min_freq(cpudata);
> @@ -1076,9 +1075,9 @@ static void amd_pstate_epp_init(unsigned int cpu)
> value |= (u64)epp << 24;
> }
>
> + amd_pstate_set_epp(cpudata, epp);
> skip_epp:
> WRITE_ONCE(cpudata->cppc_req_cached, value);
> - amd_pstate_set_epp(cpudata, epp);
> cpufreq_cpu_put(policy);
> }
>
> --
> 2.39.1
>
Hi Arnd, Ray, Perry,
On 07 Feb 17:12, Arnd Bergmann wrote:
> @@ -1076,9 +1075,9 @@ static void amd_pstate_epp_init(unsigned int cpu)
> value |= (u64)epp << 24;
> }
>
> + amd_pstate_set_epp(cpudata, epp);
> skip_epp:
> WRITE_ONCE(cpudata->cppc_req_cached, value);
> - amd_pstate_set_epp(cpudata, epp);
> cpufreq_cpu_put(policy);
> }
I see an issue here with MSR-based systems.
Here EPP is being set before updating `cppc_req_cached` and for MSR
based systems while updating EPP value, MIN_PERF and MAX_PERF also
updated. So, here whatever value MSR_AMD_CPPC_REQ had for min and max
perf that will be rewritten instead of highest and lowest perf from
MSR_AMD_CPPC_CAP1.
Can we do something like this:
@@ -1053,32 +1052,34 @@ static void amd_pstate_epp_init(unsigned int
cpu)
value &= ~AMD_CPPC_DES_PERF(~0L);
value |= AMD_CPPC_DES_PERF(0);
+ /* No need to set epp again if previous and current policy is same */
if (cpudata->epp_policy == cpudata->policy)
goto skip_epp;
cpudata->epp_policy = cpudata->policy;
- if (cpudata->policy == CPUFREQ_POLICY_PERFORMANCE) {
- epp = amd_pstate_get_epp(cpudata, value);
- if (epp < 0)
- goto skip_epp;
- /* force the epp value to be zero for performance policy */
- epp = 0;
- } else {
- /* Get BIOS pre-defined epp value */
- epp = amd_pstate_get_epp(cpudata, value);
- if (epp)
- goto skip_epp;
+ /* Get BIOS pre-defined epp value */
+ epp = amd_pstate_get_epp(cpudata, value);
+ if (epp < 0) {
+ /**
+ * This return value can only be negative for shared_memory
+ * systems where EPP register read/write not supported.
+ */
+ goto skip_epp;
}
+
+ if (cpudata->policy == CPUFREQ_POLICY_PERFORMANCE)
+ epp = 0;
+
/* Set initial EPP value */
if (boot_cpu_has(X86_FEATURE_CPPC)) {
value &= ~GENMASK_ULL(31, 24);
value |= (u64)epp << 24;
}
-skip_epp:
WRITE_ONCE(cpudata->cppc_req_cached, value);
amd_pstate_set_epp(cpudata, epp);
+skip_epp:
cpufreq_cpu_put(policy);
}
>
> --
> 2.39.1
>
On Thu, Feb 9, 2023 at 6:04 AM Huang Rui <[email protected]> wrote:
>
> On Wed, Feb 08, 2023 at 12:12:51AM +0800, Arnd Bergmann wrote:
> > From: Arnd Bergmann <[email protected]>
> >
> > The new epp support causes warnings about three separate
> > but related bugs:
> >
> > 1) failing before allocation should just return an error:
> >
> > drivers/cpufreq/amd-pstate.c:951:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> > if (!dev)
> > ^~~~
> > drivers/cpufreq/amd-pstate.c:1018:9: note: uninitialized use occurs here
> > return ret;
> > ^~~
> >
> > 2) wrong variable to store return code:
> >
> > drivers/cpufreq/amd-pstate.c:963:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> > if (rc)
> > ^~
> > drivers/cpufreq/amd-pstate.c:1019:9: note: uninitialized use occurs here
> > return ret;
> > ^~~
> > drivers/cpufreq/amd-pstate.c:963:2: note: remove the 'if' if its condition is always false
> > if (rc)
> > ^~~~~~~
> >
> > 3) calling amd_pstate_set_epp() in cleanup path after determining
> > that it should not be called:
> >
> > drivers/cpufreq/amd-pstate.c:1055:6: error: variable 'epp' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> > if (cpudata->epp_policy == cpudata->policy)
> > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > drivers/cpufreq/amd-pstate.c:1080:30: note: uninitialized use occurs here
> > amd_pstate_set_epp(cpudata, epp);
> > ^~~
> >
> > All three are trivial to fix, but most likely there are additional bugs
> > in this function when the error handling was not really tested.
> >
> > Fixes: ffa5096a7c33 ("cpufreq: amd-pstate: implement Pstate EPP support for the AMD processors")
> > Signed-off-by: Arnd Bergmann <[email protected]>
>
> Thanks!
>
> Acked-by: Huang Rui <[email protected]>
>
> > ---
> > drivers/cpufreq/amd-pstate.c | 9 ++++-----
> > 1 file changed, 4 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> > index 168a28bed6ee..847f5f31396d 100644
> > --- a/drivers/cpufreq/amd-pstate.c
> > +++ b/drivers/cpufreq/amd-pstate.c
> > @@ -940,7 +940,6 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> > int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
> > struct amd_cpudata *cpudata;
> > struct device *dev;
> > - int rc;
> > u64 value;
> >
> > /*
> > @@ -950,7 +949,7 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> > amd_perf_ctl_reset(policy->cpu);
> > dev = get_cpu_device(policy->cpu);
> > if (!dev)
> > - goto free_cpudata1;
> > + return -ENODEV;
> >
> > cpudata = kzalloc(sizeof(*cpudata), GFP_KERNEL);
> > if (!cpudata)
> > @@ -959,8 +958,8 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> > cpudata->cpu = policy->cpu;
> > cpudata->epp_policy = 0;
> >
> > - rc = amd_pstate_init_perf(cpudata);
> > - if (rc)
> > + ret = amd_pstate_init_perf(cpudata);
> > + if (ret)
> > goto free_cpudata1;
> >
> > min_freq = amd_get_min_freq(cpudata);
> > @@ -1076,9 +1075,9 @@ static void amd_pstate_epp_init(unsigned int cpu)
> > value |= (u64)epp << 24;
> > }
> >
> > + amd_pstate_set_epp(cpudata, epp);
> > skip_epp:
> > WRITE_ONCE(cpudata->cppc_req_cached, value);
> > - amd_pstate_set_epp(cpudata, epp);
> > cpufreq_cpu_put(policy);
> > }
> >
> > --
Applied, thanks!