commit 72f2ecb7ece7 ("ACPI: bus: Set CPPC _OSC bits for all and
when CPPC_LIB is supported") added support for claiming to
support CPPC in _OSC on non-Intel platforms.
This unfortunately caused a regression on a vartiety of AMD
platforms in the field because a number of AMD platforms don't set
the `_OSC` bit 5 or 6 to indicate CPPC or CPPC v2 support.
As these AMD platforms already claim CPPC support via `X86_FEATURE_CPPC`,
use this enable this feature rather than requiring the `_OSC`.
Fixes: 72f2ecb7ece7 ("Set CPPC _OSC bits for all and when CPPC_LIB is supported")
Reported-by: Perry Yuan <[email protected]>
Signed-off-by: Mario Limonciello <[email protected]>
---
drivers/acpi/cppc_acpi.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 903528f7e187..5463e6309b9a 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -629,6 +629,15 @@ static bool is_cppc_supported(int revision, int num_ent)
return false;
}
+ if (osc_sb_cppc_not_supported) {
+ pr_debug("Firmware missing _OSC support\n");
+#ifdef CONFIG_X86
+ return boot_cpu_has(X86_FEATURE_CPPC);
+#else
+ return false;
+#endif
+ }
+
return true;
}
@@ -684,9 +693,6 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
acpi_status status;
int ret = -ENODATA;
- if (osc_sb_cppc_not_supported)
- return -ENODEV;
-
/* Parse the ACPI _CPC table for this CPU. */
status = acpi_evaluate_object_typed(handle, "_CPC", NULL, &output,
ACPI_TYPE_PACKAGE);
--
2.34.1
[AMD Official Use Only - General]
Hi Rafael:
> -----Original Message-----
> From: Limonciello, Mario <[email protected]>
> Sent: Tuesday, June 28, 2022 12:59 AM
> To: Limonciello, Mario <[email protected]>; Rafael J. Wysocki
> <[email protected]>; Len Brown <[email protected]>; Pierre Gondois
> <[email protected]>; Sudeep Holla <[email protected]>
> Cc: Yuan, Perry <[email protected]>; [email protected]; linux-
> [email protected]
> Subject: [PATCH] ACPI: CPPC: Don't require _OSC if X86_FEATURE_CPPC is
> supported
>
> commit 72f2ecb7ece7 ("ACPI: bus: Set CPPC _OSC bits for all and when
> CPPC_LIB is supported") added support for claiming to support CPPC in _OSC
> on non-Intel platforms.
>
> This unfortunately caused a regression on a vartiety of AMD platforms in the
> field because a number of AMD platforms don't set the `_OSC` bit 5 or 6 to
> indicate CPPC or CPPC v2 support.
>
> As these AMD platforms already claim CPPC support via
> `X86_FEATURE_CPPC`, use this enable this feature rather than requiring the
> `_OSC`.
>
> Fixes: 72f2ecb7ece7 ("Set CPPC _OSC bits for all and when CPPC_LIB is
> supported")
> Reported-by: Perry Yuan <[email protected]>
> Signed-off-by: Mario Limonciello <[email protected]>
> ---
> drivers/acpi/cppc_acpi.c | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c index
> 903528f7e187..5463e6309b9a 100644
> --- a/drivers/acpi/cppc_acpi.c
> +++ b/drivers/acpi/cppc_acpi.c
> @@ -629,6 +629,15 @@ static bool is_cppc_supported(int revision, int
> num_ent)
> return false;
> }
>
> + if (osc_sb_cppc_not_supported) {
> + pr_debug("Firmware missing _OSC support\n"); #ifdef
> CONFIG_X86
> + return boot_cpu_has(X86_FEATURE_CPPC); #else
> + return false;
> +#endif
> + }
> +
> return true;
> }
>
I align with Mario to use his patch to fix the amd pstate driver loading failure issue.
AMD CPUID include the cppc flag to mark the CPPC valid if the _OSC dose not have the CPPC support info added.
Tested-by: Perry Yuan <[email protected]>
> @@ -684,9 +693,6 @@ int acpi_cppc_processor_probe(struct
> acpi_processor *pr)
> acpi_status status;
> int ret = -ENODATA;
>
> - if (osc_sb_cppc_not_supported)
> - return -ENODEV;
> -
> /* Parse the ACPI _CPC table for this CPU. */
> status = acpi_evaluate_object_typed(handle, "_CPC", NULL, &output,
> ACPI_TYPE_PACKAGE);
> --
> 2.34.1
On Mon, Jun 27, 2022 at 6:58 PM Mario Limonciello
<[email protected]> wrote:
>
> commit 72f2ecb7ece7 ("ACPI: bus: Set CPPC _OSC bits for all and
> when CPPC_LIB is supported") added support for claiming to
> support CPPC in _OSC on non-Intel platforms.
>
> This unfortunately caused a regression on a vartiety of AMD
> platforms in the field because a number of AMD platforms don't set
> the `_OSC` bit 5 or 6 to indicate CPPC or CPPC v2 support.
>
> As these AMD platforms already claim CPPC support via `X86_FEATURE_CPPC`,
> use this enable this feature rather than requiring the `_OSC`.
>
> Fixes: 72f2ecb7ece7 ("Set CPPC _OSC bits for all and when CPPC_LIB is supported")
> Reported-by: Perry Yuan <[email protected]>
> Signed-off-by: Mario Limonciello <[email protected]>
> ---
> drivers/acpi/cppc_acpi.c | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> index 903528f7e187..5463e6309b9a 100644
> --- a/drivers/acpi/cppc_acpi.c
> +++ b/drivers/acpi/cppc_acpi.c
> @@ -629,6 +629,15 @@ static bool is_cppc_supported(int revision, int num_ent)
> return false;
> }
>
> + if (osc_sb_cppc_not_supported) {
> + pr_debug("Firmware missing _OSC support\n");
> +#ifdef CONFIG_X86
> + return boot_cpu_has(X86_FEATURE_CPPC);
> +#else
> + return false;
> +#endif
What about doing
if (osc_sb_cppc_not_supported) {
pr_debug("Firmware missing _OSC support\n");
return IS_ENABLED(CONFIG_X86) && boot_cpu_has(X86_FEATURE_CPPC);
}
instead for the sake of reducing #ifdeffery?
Also, this is somewhat risky, because even if the given processor has
X86_FEATURE_CPPC set, the platform may still not want to expose CPPC
through ACPI. How's that going to work after this change?
> + }
> +
> return true;
> }
>
> @@ -684,9 +693,6 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
> acpi_status status;
> int ret = -ENODATA;
>
> - if (osc_sb_cppc_not_supported)
> - return -ENODEV;
> -
> /* Parse the ACPI _CPC table for this CPU. */
> status = acpi_evaluate_object_typed(handle, "_CPC", NULL, &output,
> ACPI_TYPE_PACKAGE);
> --
> 2.34.1
>
[Public]
> -----Original Message-----
> From: Rafael J. Wysocki <[email protected]>
> Sent: Wednesday, June 29, 2022 13:42
> To: Limonciello, Mario <[email protected]>
> Cc: Rafael J. Wysocki <[email protected]>; Len Brown <[email protected]>;
> Pierre Gondois <[email protected]>; Sudeep Holla
> <[email protected]>; Yuan, Perry <[email protected]>; ACPI Devel
> Maling List <[email protected]>; Linux Kernel Mailing List <linux-
> [email protected]>
> Subject: Re: [PATCH] ACPI: CPPC: Don't require _OSC if X86_FEATURE_CPPC is
> supported
>
> On Mon, Jun 27, 2022 at 6:58 PM Mario Limonciello
> <[email protected]> wrote:
> >
> > commit 72f2ecb7ece7 ("ACPI: bus: Set CPPC _OSC bits for all and
> > when CPPC_LIB is supported") added support for claiming to
> > support CPPC in _OSC on non-Intel platforms.
> >
> > This unfortunately caused a regression on a vartiety of AMD
> > platforms in the field because a number of AMD platforms don't set
> > the `_OSC` bit 5 or 6 to indicate CPPC or CPPC v2 support.
> >
> > As these AMD platforms already claim CPPC support via `X86_FEATURE_CPPC`,
> > use this enable this feature rather than requiring the `_OSC`.
> >
> > Fixes: 72f2ecb7ece7 ("Set CPPC _OSC bits for all and when CPPC_LIB is
> supported")
> > Reported-by: Perry Yuan <[email protected]>
> > Signed-off-by: Mario Limonciello <[email protected]>
> > ---
> > drivers/acpi/cppc_acpi.c | 12 +++++++++---
> > 1 file changed, 9 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> > index 903528f7e187..5463e6309b9a 100644
> > --- a/drivers/acpi/cppc_acpi.c
> > +++ b/drivers/acpi/cppc_acpi.c
> > @@ -629,6 +629,15 @@ static bool is_cppc_supported(int revision, int
> num_ent)
> > return false;
> > }
> >
> > + if (osc_sb_cppc_not_supported) {
> > + pr_debug("Firmware missing _OSC support\n");
> > +#ifdef CONFIG_X86
> > + return boot_cpu_has(X86_FEATURE_CPPC);
> > +#else
> > + return false;
> > +#endif
>
> What about doing
>
> if (osc_sb_cppc_not_supported) {
> pr_debug("Firmware missing _OSC support\n");
> return IS_ENABLED(CONFIG_X86) && boot_cpu_has(X86_FEATURE_CPPC);
> }
>
> instead for the sake of reducing #ifdeffery?
I don't think that would compile on non-X86. X86_FEATURE_CPPC comes as part of
arch/x86/include/asm/cpufeatures.h, which I wouldn't expect is included on !x86.
>
> Also, this is somewhat risky, because even if the given processor has
> X86_FEATURE_CPPC set, the platform may still not want to expose CPPC
> through ACPI. How's that going to work after this change?
>
Well actually doing that through _OSC wouldn't have worked before 72f2ecb7ece7 either.
If desirable - a platform could avoid populating _CPC objects in ACPI tables in this case.
I do know of OEM platforms that the underlying APU supports CPPC but the OEM doesn't
populate _CPC. Presumably for this exact reason.
>
> > + }
> > +
> > return true;
> > }
> >
> > @@ -684,9 +693,6 @@ int acpi_cppc_processor_probe(struct acpi_processor
> *pr)
> > acpi_status status;
> > int ret = -ENODATA;
> >
> > - if (osc_sb_cppc_not_supported)
> > - return -ENODEV;
> > -
> > /* Parse the ACPI _CPC table for this CPU. */
> > status = acpi_evaluate_object_typed(handle, "_CPC", NULL, &output,
> > ACPI_TYPE_PACKAGE);
> > --
> > 2.34.1
> >
On Wed, Jun 29, 2022 at 8:49 PM Limonciello, Mario
<[email protected]> wrote:
>
> [Public]
>
>
>
> > -----Original Message-----
> > From: Rafael J. Wysocki <[email protected]>
> > Sent: Wednesday, June 29, 2022 13:42
> > To: Limonciello, Mario <[email protected]>
> > Cc: Rafael J. Wysocki <[email protected]>; Len Brown <[email protected]>;
> > Pierre Gondois <[email protected]>; Sudeep Holla
> > <[email protected]>; Yuan, Perry <[email protected]>; ACPI Devel
> > Maling List <[email protected]>; Linux Kernel Mailing List <linux-
> > [email protected]>
> > Subject: Re: [PATCH] ACPI: CPPC: Don't require _OSC if X86_FEATURE_CPPC is
> > supported
> >
> > On Mon, Jun 27, 2022 at 6:58 PM Mario Limonciello
> > <[email protected]> wrote:
> > >
> > > commit 72f2ecb7ece7 ("ACPI: bus: Set CPPC _OSC bits for all and
> > > when CPPC_LIB is supported") added support for claiming to
> > > support CPPC in _OSC on non-Intel platforms.
> > >
> > > This unfortunately caused a regression on a vartiety of AMD
> > > platforms in the field because a number of AMD platforms don't set
> > > the `_OSC` bit 5 or 6 to indicate CPPC or CPPC v2 support.
> > >
> > > As these AMD platforms already claim CPPC support via `X86_FEATURE_CPPC`,
> > > use this enable this feature rather than requiring the `_OSC`.
> > >
> > > Fixes: 72f2ecb7ece7 ("Set CPPC _OSC bits for all and when CPPC_LIB is
> > supported")
> > > Reported-by: Perry Yuan <[email protected]>
> > > Signed-off-by: Mario Limonciello <[email protected]>
> > > ---
> > > drivers/acpi/cppc_acpi.c | 12 +++++++++---
> > > 1 file changed, 9 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> > > index 903528f7e187..5463e6309b9a 100644
> > > --- a/drivers/acpi/cppc_acpi.c
> > > +++ b/drivers/acpi/cppc_acpi.c
> > > @@ -629,6 +629,15 @@ static bool is_cppc_supported(int revision, int
> > num_ent)
> > > return false;
> > > }
> > >
> > > + if (osc_sb_cppc_not_supported) {
> > > + pr_debug("Firmware missing _OSC support\n");
> > > +#ifdef CONFIG_X86
> > > + return boot_cpu_has(X86_FEATURE_CPPC);
> > > +#else
> > > + return false;
> > > +#endif
> >
> > What about doing
> >
> > if (osc_sb_cppc_not_supported) {
> > pr_debug("Firmware missing _OSC support\n");
> > return IS_ENABLED(CONFIG_X86) && boot_cpu_has(X86_FEATURE_CPPC);
> > }
> >
> > instead for the sake of reducing #ifdeffery?
>
> I don't think that would compile on non-X86. X86_FEATURE_CPPC comes as part of
> arch/x86/include/asm/cpufeatures.h, which I wouldn't expect is included on !x86.
Good point.
Something like this would still look better though IMO:
if (!osc_sb_cppc_not_supported)
return true;
#ifdef CONFIG_X86
return boot_cpu_has(X86_FEATURE_CPPC);
#else
return false;
#endif
}
>
> >
> > Also, this is somewhat risky, because even if the given processor has
> > X86_FEATURE_CPPC set, the platform may still not want to expose CPPC
> > through ACPI. How's that going to work after this change?
> >
>
> Well actually doing that through _OSC wouldn't have worked before 72f2ecb7ece7 either.
> If desirable - a platform could avoid populating _CPC objects in ACPI tables in this case.
>
> I do know of OEM platforms that the underlying APU supports CPPC but the OEM doesn't
> populate _CPC. Presumably for this exact reason.
That is an option, but there is no requirement that _CPC must not be
populated when CPPC is not supported.
_OSC is the proper mechanism for negotiating CPPC support.
Still, if you know for a fact that on AMD systems X86_FEATURE_CPPC
always means that CPPC is supported, I can live with an extra vendor
check in the code above.
[AMD Official Use Only - General]
> -----Original Message-----
> From: Rafael J. Wysocki <[email protected]>
> Sent: Wednesday, June 29, 2022 14:09
> To: Limonciello, Mario <[email protected]>
> Cc: Rafael J. Wysocki <[email protected]>; Len Brown <[email protected]>;
> Pierre Gondois <[email protected]>; Sudeep Holla
> <[email protected]>; Yuan, Perry <[email protected]>; ACPI Devel
> Maling List <[email protected]>; Linux Kernel Mailing List <linux-
> [email protected]>
> Subject: Re: [PATCH] ACPI: CPPC: Don't require _OSC if X86_FEATURE_CPPC is
> supported
>
> On Wed, Jun 29, 2022 at 8:49 PM Limonciello, Mario
> <[email protected]> wrote:
> >
> > [Public]
> >
> >
> >
> > > -----Original Message-----
> > > From: Rafael J. Wysocki <[email protected]>
> > > Sent: Wednesday, June 29, 2022 13:42
> > > To: Limonciello, Mario <[email protected]>
> > > Cc: Rafael J. Wysocki <[email protected]>; Len Brown <[email protected]>;
> > > Pierre Gondois <[email protected]>; Sudeep Holla
> > > <[email protected]>; Yuan, Perry <[email protected]>; ACPI Devel
> > > Maling List <[email protected]>; Linux Kernel Mailing List <linux-
> > > [email protected]>
> > > Subject: Re: [PATCH] ACPI: CPPC: Don't require _OSC if X86_FEATURE_CPPC
> is
> > > supported
> > >
> > > On Mon, Jun 27, 2022 at 6:58 PM Mario Limonciello
> > > <[email protected]> wrote:
> > > >
> > > > commit 72f2ecb7ece7 ("ACPI: bus: Set CPPC _OSC bits for all and
> > > > when CPPC_LIB is supported") added support for claiming to
> > > > support CPPC in _OSC on non-Intel platforms.
> > > >
> > > > This unfortunately caused a regression on a vartiety of AMD
> > > > platforms in the field because a number of AMD platforms don't set
> > > > the `_OSC` bit 5 or 6 to indicate CPPC or CPPC v2 support.
> > > >
> > > > As these AMD platforms already claim CPPC support via
> `X86_FEATURE_CPPC`,
> > > > use this enable this feature rather than requiring the `_OSC`.
> > > >
> > > > Fixes: 72f2ecb7ece7 ("Set CPPC _OSC bits for all and when CPPC_LIB is
> > > supported")
> > > > Reported-by: Perry Yuan <[email protected]>
> > > > Signed-off-by: Mario Limonciello <[email protected]>
> > > > ---
> > > > drivers/acpi/cppc_acpi.c | 12 +++++++++---
> > > > 1 file changed, 9 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> > > > index 903528f7e187..5463e6309b9a 100644
> > > > --- a/drivers/acpi/cppc_acpi.c
> > > > +++ b/drivers/acpi/cppc_acpi.c
> > > > @@ -629,6 +629,15 @@ static bool is_cppc_supported(int revision, int
> > > num_ent)
> > > > return false;
> > > > }
> > > >
> > > > + if (osc_sb_cppc_not_supported) {
> > > > + pr_debug("Firmware missing _OSC support\n");
> > > > +#ifdef CONFIG_X86
> > > > + return boot_cpu_has(X86_FEATURE_CPPC);
> > > > +#else
> > > > + return false;
> > > > +#endif
> > >
> > > What about doing
> > >
> > > if (osc_sb_cppc_not_supported) {
> > > pr_debug("Firmware missing _OSC support\n");
> > > return IS_ENABLED(CONFIG_X86) &&
> boot_cpu_has(X86_FEATURE_CPPC);
> > > }
> > >
> > > instead for the sake of reducing #ifdeffery?
> >
> > I don't think that would compile on non-X86. X86_FEATURE_CPPC comes as
> part of
> > arch/x86/include/asm/cpufeatures.h, which I wouldn't expect is included on
> !x86.
>
> Good point.
>
> Something like this would still look better though IMO:
>
> if (!osc_sb_cppc_not_supported)
> return true;
>
> #ifdef CONFIG_X86
> return boot_cpu_has(X86_FEATURE_CPPC);
> #else
> return false;
> #endif
> }
>
Thanks, I'll respin it with something similar to that.
>
> >
> > >
> > > Also, this is somewhat risky, because even if the given processor has
> > > X86_FEATURE_CPPC set, the platform may still not want to expose CPPC
> > > through ACPI. How's that going to work after this change?
> > >
> >
> > Well actually doing that through _OSC wouldn't have worked before
> 72f2ecb7ece7 either.
> > If desirable - a platform could avoid populating _CPC objects in ACPI tables in
> this case.
> >
> > I do know of OEM platforms that the underlying APU supports CPPC but the
> OEM doesn't
> > populate _CPC. Presumably for this exact reason.
>
> That is an option, but there is no requirement that _CPC must not be
> populated when CPPC is not supported.
>
> _OSC is the proper mechanism for negotiating CPPC support.
>
Right; I agree this should have been the proper mechanism. I'll talk to
our internal BIOS team to double check reference BIOS is populated
with this correctly for programs going forward too.
> Still, if you know for a fact that on AMD systems X86_FEATURE_CPPC
> always means that CPPC is supported, I can live with an extra vendor
> check in the code above.
Thanks. The definition of that CPUID 8000_0008 EBX bit 27 used
to populate X86_FEATURE_CPPC indicates whether the CPU/APU
supports the dedicated MSR. There are also technically designs that can
work in shared memory mode that I think the only way to "safely" discover
will be via the _OSC. If this same regression from 72f2ecb7ece7 crops up
on those we might need to look at changing the amd-pstate module parameter
override that enables it for shared memory into a general kernel command line
override for users to use.