linux-kernel - Re: [PATCH] x86/cstate: Allow ACPI C1 FFH MWAIT use on Hygon systems

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Message-ID: <CAJZ5v0j-9zZvuSyKtRYePHE6aSr824SZz=E6VS_Ysv3cByGZyQ@mail.gmail.com>
Date:   Wed, 9 Jun 2021 19:30:45 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Pu Wen <puwen@...on.cn>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...e.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        "the arch/x86 maintainers" <x86@...nel.org>,
        Linux PM <linux-pm@...r.kernel.org>
Subject: Re: [PATCH] x86/cstate: Allow ACPI C1 FFH MWAIT use on Hygon systems

On Fri, May 28, 2021 at 10:44 AM Pu Wen <puwen@...on.cn> wrote:
>
> Hygon systems support the Monitor/Mwait instructions and these can be used
> for ACPI C1 in the same way as on AMD and Intel systems.
>
> The BIOS declares a C1 state in _CST to use FFH and CPUID_Fn00000005_EDX
> is non-zero on Hygon systems.
>
> Allow ffh_cstate_init() to succeed on Hygon systems to default using FFH
> MWAIT instead of HALT for ACPI C1.
>
> Tested successfully on Hygon Fam18h systems.
>
> Signed-off-by: Pu Wen <puwen@...on.cn>
> ---
>  arch/x86/kernel/acpi/cstate.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
> index 49ae4e1ac9cd..7de599eba7f0 100644
> --- a/arch/x86/kernel/acpi/cstate.c
> +++ b/arch/x86/kernel/acpi/cstate.c
> @@ -197,7 +197,8 @@ 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_AMD &&
> +           c->x86_vendor != X86_VENDOR_HYGON)
>                 return -1;
>
>         cpu_cstate_entry = alloc_percpu(struct cstate_entry);
> --

Applied as 5.14 material, thanks!