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

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Date:   Wed, 9 Jun 2021 19:39:53 +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 Wed, Jun 9, 2021 at 7:30 PM Rafael J. Wysocki <rafael@...nel.org> wrote:
>
> 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!

And dropped, because it has been applied already by Boris:
https://git.kernel.org/tip/280b68a3b3b96b027fcdeb5a3916a8e2aaf84d03