linux-kernel - Re: [PATCH 1/2] x86: notify hypervisor about guest entering s2idle state

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Date:   Thu, 16 Jun 2022 16:48:15 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Grzegorz Jaszczyk <jaz@...ihalf.com>
Cc:     linux-kernel@...r.kernel.org, Dmytro Maluka <dmy@...ihalf.com>,
        Zide Chen <zide.chen@...el.corp-partner.google.com>,
        Peter Fang <peter.fang@...el.corp-partner.google.com>,
        Tomasz Nowicki <tn@...ihalf.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Jonathan Corbet <corbet@....net>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>, Pavel Machek <pavel@....cz>,
        Ashish Kalra <ashish.kalra@....com>,
        Mario Limonciello <mario.limonciello@....com>,
        Hans de Goede <hdegoede@...hat.com>,
        Sachi King <nakato@...ato.io>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        David Dunn <daviddunn@...gle.com>,
        Wei Wang <wei.w.wang@...el.com>,
        Nicholas Piggin <npiggin@...il.com>,
        "open list:KERNEL VIRTUAL MACHINE (KVM)" <kvm@...r.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        "open list:ACPI" <linux-acpi@...r.kernel.org>,
        "open list:HIBERNATION (aka Software Suspend, aka swsusp)" 
        <linux-pm@...r.kernel.org>, Dominik Behr <dbehr@...gle.com>,
        Dmitry Torokhov <dtor@...gle.com>
Subject: Re: [PATCH 1/2] x86: notify hypervisor about guest entering s2idle
 state

On Wed, Jun 15, 2022, Grzegorz Jaszczyk wrote:
> pt., 10 cze 2022 o 16:30 Sean Christopherson <seanjc@...gle.com> napisał(a):
> > MMIO or PIO for the actual exit, there's nothing special about hypercalls.  As for
> > enumerating to the guest that it should do something, why not add a new ACPI_LPS0_*
> > function?  E.g. something like
> >
> > static void s2idle_hypervisor_notify(void)
> > {
> >         if (lps0_dsm_func_mask > 0)
> >                 acpi_sleep_run_lps0_dsm(ACPI_LPS0_EXIT_HYPERVISOR_NOTIFY
> >                                         lps0_dsm_func_mask, lps0_dsm_guid);
> > }
> 
> Great, thank you for your suggestion! I will try this approach and
> come back. Since this will be the main change in the next version,
> will it be ok for you to add Suggested-by: Sean Christopherson
> <seanjc@...gle.com> tag?

If you want, but there's certainly no need to do so.  But I assume you or someone
at Intel will need to get formal approval for adding another ACPI LPS0 function?
I.e. isn't there work to be done outside of the kernel before any patches can be
merged?