From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Andi Kleen <ak@linux.intel.com>, Borislav Petkov <bp@alien8.de>,
Dan Williams <dan.j.williams@intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Tony Luck <tony.luck@intel.com>,
the arch/x86 maintainers <x86@kernel.org>
Subject: Re: [PATCH 3/4] ACPI: processor idle: Only flush cache on entering C3
Date: Thu, 9 Dec 2021 16:33:35 +0300 [thread overview]
Message-ID: <20211209133335.u4suzd2u5sjly67l@black.fi.intel.com> (raw)
In-Reply-To: <CAJZ5v0hjcKn0g=Tc90aK_EchOG+sWi8na1HVb0GdtQsYn7sAKQ@mail.gmail.com>
On Wed, Dec 08, 2021 at 05:26:12PM +0100, Rafael J. Wysocki wrote:
> On Mon, Dec 6, 2021 at 4:03 PM Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > On Mon, Dec 06, 2021 at 03:29:51PM +0300, Kirill A. Shutemov wrote:
> > > According to the ACPI spec v6.4, section 8.2, cache flushing required
> > > on entering C3 power state.
> > >
> > > Avoid flushing cache on entering other power states.
> > >
> > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> > > ---
> > > drivers/acpi/processor_idle.c | 3 ++-
> > > 1 file changed, 2 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> > > index 76ef1bcc8848..01495aca850e 100644
> > > --- a/drivers/acpi/processor_idle.c
> > > +++ b/drivers/acpi/processor_idle.c
> > > @@ -567,7 +567,8 @@ static int acpi_idle_play_dead(struct cpuidle_device *dev, int index)
> > > {
> > > struct acpi_processor_cx *cx = per_cpu(acpi_cstate[index], dev->cpu);
> > >
> > > - ACPI_FLUSH_CPU_CACHE();
> > > + if (cx->type == ACPI_STATE_C3)
> > > + ACPI_FLUSH_CPU_CACHE();
> > >
> >
> > acpi_idle_enter() already does this, acpi_idle_enter_s2idle() has it
> > confused again,
>
> No, they do the same thing: acpi_idle_enter_bm() if flags.bm_check is set.
>
> > Also, I think acpi_idle_enter() does it too late; consider
> > acpi_idle_enter_mb(). Either that or the BM crud needs more comments.
>
> I think the latter.
>
> Evidently, acpi_idle_play_dead(() doesn't support FFH and the BM
> thing, so it is only necessary to flush the cache when using
> ACPI_CSTATE_SYSTEMIO and when cx->type is C3.
I'm new to this and not completely follow what I need to change.
Does it look correct?
From 3c544bc95a16d6a23dcb0aa50ee905d5e97c9ce5 Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Date: Thu, 9 Dec 2021 16:24:44 +0300
Subject: [PATCH] ACPI: processor idle: Only flush cache on entering C3
According to the ACPI spec v6.4, section 8.2, cache flushing required
on entering C3 power state.
Avoid flushing cache on entering other power states.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
drivers/acpi/processor_idle.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 76ef1bcc8848..d2a4d4446eff 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -567,7 +567,9 @@ static int acpi_idle_play_dead(struct cpuidle_device *dev, int index)
{
struct acpi_processor_cx *cx = per_cpu(acpi_cstate[index], dev->cpu);
- ACPI_FLUSH_CPU_CACHE();
+ if (cx->entry_method == ACPI_CSTATE_SYSTEMIO &&
+ cx->type == ACPI_STATE_C3)
+ ACPI_FLUSH_CPU_CACHE();
while (1) {
--
Kirill A. Shutemov
next prev parent reply other threads:[~2021-12-09 13:33 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <YZPbQVwWOJCrAH78@zn.tnic>
2021-11-19 4:03 ` [PATCH v2] x86: Skip WBINVD instruction for VM guest Kuppuswamy Sathyanarayanan
2021-11-25 0:40 ` Thomas Gleixner
2021-12-02 22:21 ` Kirill A. Shutemov
2021-12-02 22:38 ` Dave Hansen
2021-12-02 23:48 ` Thomas Gleixner
2021-12-03 23:49 ` Kirill A. Shutemov
2021-12-04 0:20 ` Dave Hansen
2021-12-04 0:54 ` Kirill A. Shutemov
2021-12-06 15:35 ` Dave Hansen
2021-12-06 16:39 ` Dan Williams
2021-12-06 16:53 ` Dave Hansen
2021-12-06 17:51 ` Dan Williams
2021-12-04 20:27 ` Rafael J. Wysocki
2021-12-06 12:29 ` [PATCH 0/4] ACPI/ACPICA: Only flush caches on S1/S2/S3 and C3 Kirill A. Shutemov
2021-12-06 12:29 ` [PATCH 1/4] ACPICA: Do not flush cache for on entering S4 and S5 Kirill A. Shutemov
2021-12-08 14:58 ` Rafael J. Wysocki
2021-12-06 12:29 ` [PATCH 2/4] ACPI: PM: Remove redundant cache flushing Kirill A. Shutemov
2021-12-07 16:35 ` Rafael J. Wysocki
2021-12-09 13:32 ` Kirill A. Shutemov
2021-12-17 18:04 ` Rafael J. Wysocki
2021-12-06 12:29 ` [PATCH 3/4] ACPI: processor idle: Only flush cache on entering C3 Kirill A. Shutemov
2021-12-06 15:03 ` Peter Zijlstra
2021-12-08 16:26 ` Rafael J. Wysocki
2021-12-09 13:33 ` Kirill A. Shutemov [this message]
2021-12-17 17:58 ` Rafael J. Wysocki
2021-12-06 12:29 ` [PATCH 4/4] ACPI: PM: Avoid cache flush on entering S4 Kirill A. Shutemov
2021-12-08 15:10 ` Rafael J. Wysocki
2021-12-08 16:04 ` Kirill A. Shutemov
2021-12-08 16:16 ` Rafael J. Wysocki
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