* [PATCH 1/2] x86: Fix return value in frequency invariance setup for XEON_PHI_KNL/KNM
@ 2022-05-20 16:10 Giovanni Gherdovich
2022-05-20 16:10 ` [PATCH 2/2] x86: fix platform info detection in frequency invariance Giovanni Gherdovich
2022-05-21 10:02 ` [PATCH 1/2] x86: Fix return value in frequency invariance setup for XEON_PHI_KNL/KNM Peter Zijlstra
0 siblings, 2 replies; 6+ messages in thread
From: Giovanni Gherdovich @ 2022-05-20 16:10 UTC (permalink / raw)
To: Borislav Petkov, Ingo Molnar, Peter Zijlstra, Dave Hansen,
Thomas Gleixner
Cc: Rafael J . Wysocki, Dan Carpenter, Srinivas Pandruvada, x86,
linux-kernel, Giovanni Gherdovich
knl_set_max_freq_ratio() should return true on success and false
otherwise. If the last line of the function body is reached, it means no
appropriate value for turbo_freq was found: the setup is unsuccessful and
it should return false.
Fixes: 8bea0dfb4a82 ("x86, sched: Add support for frequency invariance on XEON_PHI_KNL/KNM")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Giovanni Gherdovich <ggherdovich@suse.cz>
---
arch/x86/kernel/smpboot.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 2ef14772dc04..225a3c31297c 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1985,7 +1985,7 @@ static bool knl_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq,
i += 8;
} while (i < 64);
- return true;
+ return false;
}
static bool skx_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq, int size)
--
2.31.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 2/2] x86: fix platform info detection in frequency invariance
2022-05-20 16:10 [PATCH 1/2] x86: Fix return value in frequency invariance setup for XEON_PHI_KNL/KNM Giovanni Gherdovich
@ 2022-05-20 16:10 ` Giovanni Gherdovich
2022-05-20 16:44 ` Dave Hansen
2022-05-21 10:02 ` [PATCH 1/2] x86: Fix return value in frequency invariance setup for XEON_PHI_KNL/KNM Peter Zijlstra
1 sibling, 1 reply; 6+ messages in thread
From: Giovanni Gherdovich @ 2022-05-20 16:10 UTC (permalink / raw)
To: Borislav Petkov, Ingo Molnar, Peter Zijlstra, Dave Hansen,
Thomas Gleixner
Cc: Rafael J . Wysocki, Dan Carpenter, Srinivas Pandruvada, x86,
linux-kernel, Giovanni Gherdovich
Once the microarchitecture is recognized (via x86_match_cpu()), a failure
in setting base_freq/turbo_freq should result in bailing out from frequency
invariance, not in trying the next microarchitecture. This is because the
call to core_set_max_freq_ratio() isn't guarded by x86_match_cpu(). The
call to core_set_max_freq_ratio() should happen if no more specific
microarch matched, but not in case of prior errors.
Initializing base_freq=0 and turbo_freq=0 gives a mean for later code to
check if setup failed.
Fixes: db441bd9f630 ("x86, sched: Move check for CPU type to caller function")
Signed-off-by: Giovanni Gherdovich <ggherdovich@suse.cz>
---
arch/x86/kernel/smpboot.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 225a3c31297c..d0a692ea8294 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -2044,23 +2044,26 @@ static bool core_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq)
static bool intel_set_max_freq_ratio(void)
{
- u64 base_freq, turbo_freq;
+ u64 base_freq = 0, turbo_freq = 0;
u64 turbo_ratio;
if (slv_set_max_freq_ratio(&base_freq, &turbo_freq))
goto out;
- if (x86_match_cpu(has_glm_turbo_ratio_limits) &&
- skx_set_max_freq_ratio(&base_freq, &turbo_freq, 1))
+ if (x86_match_cpu(has_glm_turbo_ratio_limits)) {
+ skx_set_max_freq_ratio(&base_freq, &turbo_freq, 1);
goto out;
+ }
- if (x86_match_cpu(has_knl_turbo_ratio_limits) &&
- knl_set_max_freq_ratio(&base_freq, &turbo_freq, 1))
+ if (x86_match_cpu(has_knl_turbo_ratio_limits)) {
+ knl_set_max_freq_ratio(&base_freq, &turbo_freq, 1);
goto out;
+ }
- if (x86_match_cpu(has_skx_turbo_ratio_limits) &&
- skx_set_max_freq_ratio(&base_freq, &turbo_freq, 4))
+ if (x86_match_cpu(has_skx_turbo_ratio_limits)) {
+ skx_set_max_freq_ratio(&base_freq, &turbo_freq, 4);
goto out;
+ }
if (core_set_max_freq_ratio(&base_freq, &turbo_freq))
goto out;
--
2.31.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH 2/2] x86: fix platform info detection in frequency invariance
2022-05-20 16:10 ` [PATCH 2/2] x86: fix platform info detection in frequency invariance Giovanni Gherdovich
@ 2022-05-20 16:44 ` Dave Hansen
2022-05-23 9:56 ` Giovanni Gherdovich
0 siblings, 1 reply; 6+ messages in thread
From: Dave Hansen @ 2022-05-20 16:44 UTC (permalink / raw)
To: Giovanni Gherdovich, Borislav Petkov, Ingo Molnar,
Peter Zijlstra, Dave Hansen, Thomas Gleixner
Cc: Rafael J . Wysocki, Dan Carpenter, Srinivas Pandruvada, x86,
linux-kernel
On 5/20/22 09:10, Giovanni Gherdovich wrote:
> if (slv_set_max_freq_ratio(&base_freq, &turbo_freq))
> goto out;
>
> - if (x86_match_cpu(has_glm_turbo_ratio_limits) &&
> - skx_set_max_freq_ratio(&base_freq, &turbo_freq, 1))
> + if (x86_match_cpu(has_glm_turbo_ratio_limits)) {
> + skx_set_max_freq_ratio(&base_freq, &turbo_freq, 1);
> goto out;
> + }
>
> - if (x86_match_cpu(has_knl_turbo_ratio_limits) &&
> - knl_set_max_freq_ratio(&base_freq, &turbo_freq, 1))
> + if (x86_match_cpu(has_knl_turbo_ratio_limits)) {
> + knl_set_max_freq_ratio(&base_freq, &turbo_freq, 1);
> goto out;
> + }
>
> - if (x86_match_cpu(has_skx_turbo_ratio_limits) &&
> - skx_set_max_freq_ratio(&base_freq, &turbo_freq, 4))
> + if (x86_match_cpu(has_skx_turbo_ratio_limits)) {
> + skx_set_max_freq_ratio(&base_freq, &turbo_freq, 4);
> goto out;
> + }
>
> if (core_set_max_freq_ratio(&base_freq, &turbo_freq))
> goto out;
But didn't the last patch in the series carefully change the return
value for knl_set_max_freq_ratio()? Now, the only call site is ignoring
the return value? That seems odd.
Also, this is a mess. These constructs:
static const struct x86_cpu_id has_knl_turbo_ratio_limits[] = {
X86_MATCH(XEON_PHI_KNL),
X86_MATCH(XEON_PHI_KNM),
{}
};
static const struct x86_cpu_id has_skx_turbo_ratio_limits[] = {
X86_MATCH(SKYLAKE_X),
{}
};
static const struct x86_cpu_id has_glm_turbo_ratio_limits[] = {
X86_MATCH(ATOM_GOLDMONT),
X86_MATCH(ATOM_GOLDMONT_D),
X86_MATCH(ATOM_GOLDMONT_PLUS),
{}
};
are rather goofy. A single array like rapl_ids[] that points to the
handler function would do us a lot more good here, say:
static const struct x86_cpu_id has_knl_turbo_ratio_limits[] = {
X86_MATCH(XEON_PHI_KNL, &knl_set_max_freq_ratio),
X86_MATCH(XEON_PHI_KNM, &knl_set_max_freq_ratio),
X86_MATCH(SKYLAKE_X, &skx_set_max_freq_ratio),
X86_MATCH(ATOM_GOLDMONT, &skx_set_max_freq_ratio),
X86_MATCH(ATOM_GOLDMONT_D, &skx_set_max_freq_ratio),
X86_MATCH(ATOM_GOLDMONT_PLUS, &skx_set_max_freq_ratio),
X86_MATCH(ANY, &core_set_max_freq_ratio),
{}
};
That would get rid of all the goofy gotos and actually puts all the
logic in one place. BTW, I'm not 100% sure about the 'ANY' line. I
think that's how those work, but please double-check me on it.
While it's generally best to keep bug fixes to a minimum, I think this
one is worth a bit of a cleanup because it will remove a bunch of spaghetti.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/2] x86: Fix return value in frequency invariance setup for XEON_PHI_KNL/KNM
2022-05-20 16:10 [PATCH 1/2] x86: Fix return value in frequency invariance setup for XEON_PHI_KNL/KNM Giovanni Gherdovich
2022-05-20 16:10 ` [PATCH 2/2] x86: fix platform info detection in frequency invariance Giovanni Gherdovich
@ 2022-05-21 10:02 ` Peter Zijlstra
2022-05-23 9:57 ` Giovanni Gherdovich
1 sibling, 1 reply; 6+ messages in thread
From: Peter Zijlstra @ 2022-05-21 10:02 UTC (permalink / raw)
To: Giovanni Gherdovich
Cc: Borislav Petkov, Ingo Molnar, Dave Hansen, Thomas Gleixner,
Rafael J . Wysocki, Dan Carpenter, Srinivas Pandruvada, x86,
linux-kernel
On Fri, May 20, 2022 at 06:10:21PM +0200, Giovanni Gherdovich wrote:
> knl_set_max_freq_ratio() should return true on success and false
> otherwise. If the last line of the function body is reached, it means no
> appropriate value for turbo_freq was found: the setup is unsuccessful and
> it should return false.
>
> Fixes: 8bea0dfb4a82 ("x86, sched: Add support for frequency invariance on XEON_PHI_KNL/KNM")
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Signed-off-by: Giovanni Gherdovich <ggherdovich@suse.cz>
> ---
> arch/x86/kernel/smpboot.c | 2 +-
You seems to have missed all that code moved in tip. This no longer
applies.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 2/2] x86: fix platform info detection in frequency invariance
2022-05-20 16:44 ` Dave Hansen
@ 2022-05-23 9:56 ` Giovanni Gherdovich
0 siblings, 0 replies; 6+ messages in thread
From: Giovanni Gherdovich @ 2022-05-23 9:56 UTC (permalink / raw)
To: Dave Hansen, Borislav Petkov, Ingo Molnar, Peter Zijlstra,
Dave Hansen, Thomas Gleixner
Cc: Rafael J . Wysocki, Dan Carpenter, Srinivas Pandruvada, x86,
linux-kernel
On Fri, 2022-05-20 at 09:44 -0700, Dave Hansen wrote:
> On 5/20/22 09:10, Giovanni Gherdovich wrote:
> > if (slv_set_max_freq_ratio(&base_freq, &turbo_freq))
> > goto out;
> >
> > - if (x86_match_cpu(has_glm_turbo_ratio_limits) &&
> > - skx_set_max_freq_ratio(&base_freq, &turbo_freq, 1))
> > + if (x86_match_cpu(has_glm_turbo_ratio_limits)) {
> > + skx_set_max_freq_ratio(&base_freq, &turbo_freq, 1);
> > goto out;
> > + }
> >
> > - if (x86_match_cpu(has_knl_turbo_ratio_limits) &&
> > - knl_set_max_freq_ratio(&base_freq, &turbo_freq, 1))
> > + if (x86_match_cpu(has_knl_turbo_ratio_limits)) {
> > + knl_set_max_freq_ratio(&base_freq, &turbo_freq, 1);
> > goto out;
> > + }
> >
> > - if (x86_match_cpu(has_skx_turbo_ratio_limits) &&
> > - skx_set_max_freq_ratio(&base_freq, &turbo_freq, 4))
> > + if (x86_match_cpu(has_skx_turbo_ratio_limits)) {
> > + skx_set_max_freq_ratio(&base_freq, &turbo_freq, 4);
> > goto out;
> > + }
> >
> > if (core_set_max_freq_ratio(&base_freq, &turbo_freq))
> > goto out;
>
> But didn't the last patch in the series carefully change the return
> value for knl_set_max_freq_ratio()? Now, the only call site is ignoring
> the return value? That seems odd.
Thanks for having a look! You're right. I need to either check these
return values, or not have them at all.
>
> Also, this is a mess. These constructs:
>
> static const struct x86_cpu_id has_knl_turbo_ratio_limits[] = {
> X86_MATCH(XEON_PHI_KNL),
> X86_MATCH(XEON_PHI_KNM),
> {}
> };
>
> static const struct x86_cpu_id has_skx_turbo_ratio_limits[] = {
> X86_MATCH(SKYLAKE_X),
> {}
> };
>
> static const struct x86_cpu_id has_glm_turbo_ratio_limits[] = {
> X86_MATCH(ATOM_GOLDMONT),
> X86_MATCH(ATOM_GOLDMONT_D),
> X86_MATCH(ATOM_GOLDMONT_PLUS),
> {}
> };
>
> are rather goofy. A single array like rapl_ids[] that points to the
> handler function would do us a lot more good here, say:
>
> static const struct x86_cpu_id has_knl_turbo_ratio_limits[] = {
> X86_MATCH(XEON_PHI_KNL, &knl_set_max_freq_ratio),
> X86_MATCH(XEON_PHI_KNM, &knl_set_max_freq_ratio),
> X86_MATCH(SKYLAKE_X, &skx_set_max_freq_ratio),
> X86_MATCH(ATOM_GOLDMONT, &skx_set_max_freq_ratio),
> X86_MATCH(ATOM_GOLDMONT_D, &skx_set_max_freq_ratio),
> X86_MATCH(ATOM_GOLDMONT_PLUS, &skx_set_max_freq_ratio),
> X86_MATCH(ANY, &core_set_max_freq_ratio),
> {}
> };
>
> That would get rid of all the goofy gotos and actually puts all the
> logic in one place. BTW, I'm not 100% sure about the 'ANY' line. I
> think that's how those work, but please double-check me on it.
That's good advice. I'll do that consolidation.
>
> While it's generally best to keep bug fixes to a minimum, I think this
> one is worth a bit of a cleanup because it will remove a bunch of spaghetti.
Thanks,
Giovanni
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/2] x86: Fix return value in frequency invariance setup for XEON_PHI_KNL/KNM
2022-05-21 10:02 ` [PATCH 1/2] x86: Fix return value in frequency invariance setup for XEON_PHI_KNL/KNM Peter Zijlstra
@ 2022-05-23 9:57 ` Giovanni Gherdovich
0 siblings, 0 replies; 6+ messages in thread
From: Giovanni Gherdovich @ 2022-05-23 9:57 UTC (permalink / raw)
To: Peter Zijlstra
Cc: Borislav Petkov, Ingo Molnar, Dave Hansen, Thomas Gleixner,
Rafael J . Wysocki, Dan Carpenter, Srinivas Pandruvada, x86,
linux-kernel
On Sat, 2022-05-21 at 12:02 +0200, Peter Zijlstra wrote:
> On Fri, May 20, 2022 at 06:10:21PM +0200, Giovanni Gherdovich wrote:
> > knl_set_max_freq_ratio() should return true on success and false
> > otherwise. If the last line of the function body is reached, it means no
> > appropriate value for turbo_freq was found: the setup is unsuccessful and
> > it should return false.
> >
> > Fixes: 8bea0dfb4a82 ("x86, sched: Add support for frequency invariance on XEON_PHI_KNL/KNM")
> > Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> > Signed-off-by: Giovanni Gherdovich <ggherdovich@suse.cz>
> > ---
> > arch/x86/kernel/smpboot.c | 2 +-
>
> You seems to have missed all that code moved in tip. This no longer
> applies.
Right. I'll rebase and resend. Plus, as per Dave Hansen's comments on
the other patch, I need to have a second look at it.
Giovanni
^ permalink raw reply [flat|nested] 6+ messages in thread
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2022-05-20 16:10 [PATCH 1/2] x86: Fix return value in frequency invariance setup for XEON_PHI_KNL/KNM Giovanni Gherdovich
2022-05-20 16:10 ` [PATCH 2/2] x86: fix platform info detection in frequency invariance Giovanni Gherdovich
2022-05-20 16:44 ` Dave Hansen
2022-05-23 9:56 ` Giovanni Gherdovich
2022-05-21 10:02 ` [PATCH 1/2] x86: Fix return value in frequency invariance setup for XEON_PHI_KNL/KNM Peter Zijlstra
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