From: Dan Williams <dan.j.williams@intel.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
X86 ML <x86@kernel.org>, "Rafael J . Wysocki" <rjw@rjwysocki.net>,
"H . Peter Anvin" <hpa@zytor.com>,
Tony Luck <tony.luck@intel.com>, Andi Kleen <ak@linux.intel.com>,
Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux ACPI <linux-acpi@vger.kernel.org>
Subject: Re: [PATCH v2] x86: Skip WBINVD instruction for VM guest
Date: Mon, 6 Dec 2021 09:51:07 -0800 [thread overview]
Message-ID: <CAPcyv4gMaXeubx9pD18yKCZJHs60ULcMFrgsOhjBV+VFZgDy_Q@mail.gmail.com> (raw)
In-Reply-To: <e84556f2-a724-5f90-d950-b4e017eee989@intel.com>
On Mon, Dec 6, 2021 at 8:54 AM Dave Hansen <dave.hansen@intel.com> wrote:
>
> On 12/6/21 8:39 AM, Dan Williams wrote:
> >> But, the trick is that we need a contract. A contract requires a
> >> "meeting of the minds" first.
> > The WBINVD requirement in sleep states is about getting cache contents
> > out to to power preserved domain before the CPU turns off. The bare
> > metal host handles that requirement. The conversation that needs to be
> > had is with the ACPI specification committee to clarify that virtual
> > machines have no responsibility to flush caches. We can do that as a
> > Code First proposal to the ACPI Specification Working Group.
>
> Sounds sane to me. So, we effectively go to the ACPI folks and say that
> Linux isn't going to do WBINVD in virtualized environments any more.
> That was effectively the approach that the first patch in this thread did:
>
> > https://lore.kernel.org/all/20211116005027.2929297-1-sathyanarayanan.kuppuswamy@linux.intel.com/
>
> Right?
Correct, my reviewed-by was based on that observation, and now we can
close the loop by proposing the specification change.
next prev parent reply other threads:[~2021-12-06 17:51 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 [this message]
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
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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