2022-07-01 07:18:12

by Tony W Wang-oc

Subject: [PATCH] x86/cstate: Replace vendor check with X86_FEATURE_MWAIT in ffh_cstate_init

The original commit 991528d73486 ("ACPI: Processor native C-states using
MWAIT") has a vendor check for Intel in the function of ffh_cstate_init().

Commit 5209654a46ee ("x86/ACPI/cstate: Allow ACPI C1 FFH MWAIT use on AMD
systems") and commit 280b68a3b3b9 ("x86/cstate: Allow ACPI C1 FFH MWAIT
use on Hygon systems") add vendor check for AMD and HYGON in the function
of ffh_cstate_init().

Recent Zhaoxin and Centaur CPUs support MONITOR/MWAIT instructions that
can be used for ACPI Cx state in the same way as Intel. So expected to
add the support of these CPUs in the function of ffh_cstate_init() too.

The CPU feature X86_FEATURE_MWAIT indicates processor supports MONITOR/
MWAIT instructions. So the check for many CPU vendors in ffh_cstate_init()
is unnecessary, use X86_FEATURE_MWAIT to replace the CPU vendor check.

Signed-off-by: Tony W Wang-oc <[email protected]>
---
arch/x86/kernel/acpi/cstate.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
index 7945eae..a64c38f 100644
--- a/arch/x86/kernel/acpi/cstate.c
+++ b/arch/x86/kernel/acpi/cstate.c
@@ -209,11 +209,7 @@ EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_enter);

static int __init ffh_cstate_init(void)
{
- struct cpuinfo_x86 *c = &boot_cpu_data;
-
- if (c->x86_vendor != X86_VENDOR_INTEL &&
- c->x86_vendor != X86_VENDOR_AMD &&
- c->x86_vendor != X86_VENDOR_HYGON)
+ if (!boot_cpu_has(X86_FEATURE_MWAIT))
return -1;

cpu_cstate_entry = alloc_percpu(struct cstate_entry);
--
2.7.4

2022-07-05 18:53:52

by Rafael J. Wysocki

Subject: Re: [PATCH] x86/cstate: Replace vendor check with X86_FEATURE_MWAIT in ffh_cstate_init

On Fri, Jul 1, 2022 at 9:05 AM Tony W Wang-oc <[email protected]> wrote:
>
> The original commit 991528d73486 ("ACPI: Processor native C-states using
> MWAIT") has a vendor check for Intel in the function of ffh_cstate_init().
>
> Commit 5209654a46ee ("x86/ACPI/cstate: Allow ACPI C1 FFH MWAIT use on AMD
> systems") and commit 280b68a3b3b9 ("x86/cstate: Allow ACPI C1 FFH MWAIT
> use on Hygon systems") add vendor check for AMD and HYGON in the function
> of ffh_cstate_init().
>
> Recent Zhaoxin and Centaur CPUs support MONITOR/MWAIT instructions that
> can be used for ACPI Cx state in the same way as Intel. So expected to
> add the support of these CPUs in the function of ffh_cstate_init() too.
>
> The CPU feature X86_FEATURE_MWAIT indicates processor supports MONITOR/
> MWAIT instructions. So the check for many CPU vendors in ffh_cstate_init()
> is unnecessary, use X86_FEATURE_MWAIT to replace the CPU vendor check.
>
> Signed-off-by: Tony W Wang-oc <[email protected]>

Reviewed-by: Rafael J. Wysocki <[email protected]>

or please let me know if I'm expected to pick up this one. Thanks!


> ---
> arch/x86/kernel/acpi/cstate.c | 6 +-----
> 1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
> index 7945eae..a64c38f 100644
> --- a/arch/x86/kernel/acpi/cstate.c
> +++ b/arch/x86/kernel/acpi/cstate.c
> @@ -209,11 +209,7 @@ EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_enter);
>
> static int __init ffh_cstate_init(void)
> {
> - struct cpuinfo_x86 *c = &boot_cpu_data;
> -
> - if (c->x86_vendor != X86_VENDOR_INTEL &&
> - c->x86_vendor != X86_VENDOR_AMD &&
> - c->x86_vendor != X86_VENDOR_HYGON)
> + if (!boot_cpu_has(X86_FEATURE_MWAIT))
> return -1;
>
> cpu_cstate_entry = alloc_percpu(struct cstate_entry);
> --
> 2.7.4
>

2022-07-19 04:48:31

by Tony W Wang-oc

Subject: Re: [PATCH] x86/cstate: Replace vendor check with X86_FEATURE_MWAIT in ffh_cstate_init

On 2022/7/6 上午2:45, Rafael J. Wysocki wrote:
> On Fri, Jul 1, 2022 at 9:05 AM Tony W Wang-oc <[email protected]> wrote:
>>
>> The original commit 991528d73486 ("ACPI: Processor native C-states using
>> MWAIT") has a vendor check for Intel in the function of ffh_cstate_init().
>>
>> Commit 5209654a46ee ("x86/ACPI/cstate: Allow ACPI C1 FFH MWAIT use on AMD
>> systems") and commit 280b68a3b3b9 ("x86/cstate: Allow ACPI C1 FFH MWAIT
>> use on Hygon systems") add vendor check for AMD and HYGON in the function
>> of ffh_cstate_init().
>>
>> Recent Zhaoxin and Centaur CPUs support MONITOR/MWAIT instructions that
>> can be used for ACPI Cx state in the same way as Intel. So expected to
>> add the support of these CPUs in the function of ffh_cstate_init() too.
>>
>> The CPU feature X86_FEATURE_MWAIT indicates processor supports MONITOR/
>> MWAIT instructions. So the check for many CPU vendors in ffh_cstate_init()
>> is unnecessary, use X86_FEATURE_MWAIT to replace the CPU vendor check.
>>
>> Signed-off-by: Tony W Wang-oc <[email protected]>
>
> Reviewed-by: Rafael J. Wysocki <[email protected]>
>

Thanks a lot.
Add some original commit authors this patch related to.

> or please let me know if I'm expected to pick up this one. Thanks!
>

Yes for me. Thanks a lot.

>
>> ---
>> arch/x86/kernel/acpi/cstate.c | 6 +-----
>> 1 file changed, 1 insertion(+), 5 deletions(-)
>>
>> diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
>> index 7945eae..a64c38f 100644
>> --- a/arch/x86/kernel/acpi/cstate.c
>> +++ b/arch/x86/kernel/acpi/cstate.c
>> @@ -209,11 +209,7 @@ EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_enter);
>>
>> static int __init ffh_cstate_init(void)
>> {
>> - struct cpuinfo_x86 *c = &boot_cpu_data;
>> -
>> - if (c->x86_vendor != X86_VENDOR_INTEL &&
>> - c->x86_vendor != X86_VENDOR_AMD &&
>> - c->x86_vendor != X86_VENDOR_HYGON)
>> + if (!boot_cpu_has(X86_FEATURE_MWAIT))
>> return -1;
>>
>> cpu_cstate_entry = alloc_percpu(struct cstate_entry);
>> --
>> 2.7.4
>>
> .
>