From: Ingo Molnar <mingo@kernel.org>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
linux-arch <linux-arch@vger.kernel.org>,
Tom Lendacky <thomas.lendacky@amd.com>,
Andi Kleen <ak@linux.intel.com>,
Kees Cook <keescook@chromium.org>,
Kernel Hardening <kernel-hardening@lists.openwall.com>,
Greg KH <gregkh@linuxfoundation.org>, X86 ML <x86@kernel.org>,
Ingo Molnar <mingo@redhat.com>, Al Viro <viro@zeniv.linux.org.uk>,
"H. Peter Anvin" <hpa@zytor.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Alan Cox <alan@linux.intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v5 04/12] x86: introduce __uaccess_begin_nospec and ifence
Date: Tue, 30 Jan 2018 07:56:53 +0100 [thread overview]
Message-ID: <20180130065653.gsp7blb3jttd6e6t@gmail.com> (raw)
In-Reply-To: <CAPcyv4hmkJyFgCBCXR8A1ykzk1tsxX-Lg4qgimhGxne=iG1Hzg@mail.gmail.com>
* Dan Williams <dan.j.williams@intel.com> wrote:
> > The flip side is that if the MFENCE stalls the STAC that is ahead of it could be
> > processed for 'free' - while it's always post barrier with my suggestion.
>
> This 'for free' aspect is what I aiming for.
Ok.
> >
> > But in any case it would be nice to see a discussion of this aspect in the
> > changelog, even if the patch does not change.
>
> I'll add a note to the changelog that having the fence after the
> 'stac' hopefully allows some overlap of the cost of 'stac' and the
> flushing of the instruction pipeline.
Perfect!
Thanks,
Ingo
next prev parent reply other threads:[~2018-01-30 6:56 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <151703971300.26578.1185595719337719486.stgit@dwillia2-desk3.amr.corp.intel.com>
2018-01-27 19:26 ` [PATCH v5 00/12] spectre variant1 mitigations for tip/x86/pti Dan Williams
[not found] ` <151703972396.26578.7326612698912543866.stgit@dwillia2-desk3.amr.corp.intel.com>
2018-01-28 8:55 ` [PATCH v5 02/12] array_idx: sanitize speculative array de-references Ingo Molnar
2018-01-28 11:36 ` Thomas Gleixner
2018-01-28 16:28 ` Dan Williams
2018-01-28 18:33 ` Ingo Molnar
2018-01-29 16:45 ` Dan Williams
2018-01-28 18:36 ` [kernel-hardening] " Thomas Gleixner
2018-01-30 6:29 ` Dan Williams
2018-01-30 19:38 ` Linus Torvalds
2018-01-30 20:13 ` Dan Williams
2018-01-30 20:27 ` Van De Ven, Arjan
2018-01-31 8:03 ` Ingo Molnar
2018-01-31 14:13 ` Van De Ven, Arjan
2018-01-31 14:21 ` Greg KH
[not found] ` <151703972912.26578.6792656143278523491.stgit@dwillia2-desk3.amr.corp.intel.com>
2018-01-28 9:02 ` [PATCH v5 03/12] x86: implement array_idx_mask Ingo Molnar
[not found] ` <151703973427.26578.15693075353773519333.stgit@dwillia2-desk3.amr.corp.intel.com>
2018-01-28 9:14 ` [PATCH v5 04/12] x86: introduce __uaccess_begin_nospec and ifence Ingo Molnar
2018-01-29 20:41 ` Dan Williams
2018-01-30 6:56 ` Ingo Molnar [this message]
[not found] ` <151703974000.26578.2874964402485950653.stgit@dwillia2-desk3.amr.corp.intel.com>
2018-01-28 9:19 ` [PATCH v5 05/12] x86, __get_user: use __uaccess_begin_nospec Ingo Molnar
[not found] ` <151703974570.26578.3809646715924406820.stgit@dwillia2-desk3.amr.corp.intel.com>
2018-01-28 9:25 ` [PATCH v5 06/12] x86, get_user: use pointer masking to limit speculation Ingo Molnar
[not found] ` <151703975137.26578.11230688940391207602.stgit@dwillia2-desk3.amr.corp.intel.com>
2018-01-28 9:29 ` [PATCH v5 07/12] x86: remove the syscall_64 fast-path Ingo Molnar
2018-01-28 15:22 ` Andy Lutomirski
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180130065653.gsp7blb3jttd6e6t@gmail.com \
--to=mingo@kernel.org \
--cc=ak@linux.intel.com \
--cc=alan@linux.intel.com \
--cc=dan.j.williams@intel.com \
--cc=gregkh@linuxfoundation.org \
--cc=hpa@zytor.com \
--cc=keescook@chromium.org \
--cc=kernel-hardening@lists.openwall.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=tglx@linutronix.de \
--cc=thomas.lendacky@amd.com \
--cc=torvalds@linux-foundation.org \
--cc=viro@zeniv.linux.org.uk \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox