From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Babu Moger <babu.moger@amd.com>
Cc: "Moger, Babu" <bmoger@amd.com>,
bp@alien8.de, bsd@redhat.com, corbet@lwn.net, hpa@zytor.com,
linux-kernel@vger.kernel.org, mingo@redhat.com,
tglx@linutronix.de, x86@kernel.org
Subject: Re: [v6 1/1] x86/bugs: Implement mitigation for Predictive Store
Date: Wed, 8 Sep 2021 11:20:47 -0700 [thread overview]
Message-ID: <20210908182047.lcor52bjzrt35gsq@treble> (raw)
In-Reply-To: <35a32225-25d3-88eb-f427-14c93c38c97b@amd.com>
On Tue, Sep 07, 2021 at 06:15:53PM -0500, Babu Moger wrote:
> >>> Because trying to give them separate interfaces, when PSF disable is
> >>> intertwined with SSB disable in hardware, is awkward and confusing. And
> >>> the idea of adding another double-negative interface (disable=off!),
> >>> just because a vulnerability is considered to be a CPU "feature", isn't
> >>> very appetizing.
> >>>
> >>> So instead of adding a new double-negative interface, which only *half*
> >>> works due to the ssb_disable dependency, and which is guaranteed to
> >>> further confuse users, and which not even be used in the real world
> >>> except possibly by confused users...
> >>>
> >>> I'm wondering if we can just start out with the simplest possible
> >>> approach: don't change any code and instead just document the fact that
> >>> "spec_store_bypass_disable=" also affects PSF.
> >>>
> >>> Then, later on, if a real-world need is demonstrated, actual code could
> >>> be added to support disabling PSF independently (but of course it would
> >>> never be fully independent since PSF disable is forced by SSB disable).
> >>
> >> Do you mean for now keep only 'on' and 'auto' and remove "off"?
> >
> > No, since PSF can already be mitigated with SSBD today, I'm suggesting
> > that all code be removed from the patch and instead just update the
> > documentation.
> >
>
> Hmm Interesting..
> Just updating the documentation and without giving interface to enable or
> disable will not be a much of a value add.
It's also not a value add to create controls and added complexity for a
feature which nobody needs. There's no harm in starting out with the
simplest possible solution, which is no code at all.
Code can always be added later if really needed...
--
Josh
next prev parent reply other threads:[~2021-09-08 18:20 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-17 22:00 [v6 0/1] Introduce support for PSF control Ramakrishna Saripalli
2021-05-17 22:00 ` [v6 1/1] x86/bugs: Implement mitigation for Predictive Store Forwarding Ramakrishna Saripalli
2021-05-18 2:55 ` Randy Dunlap
2021-05-18 12:27 ` Saripalli, RK
2021-05-18 20:35 ` Pawan Gupta
2021-05-19 5:38 ` Pawan Gupta
2021-05-19 13:19 ` Saripalli, RK
2021-05-19 5:50 ` Pawan Gupta
2021-09-01 20:20 ` [v6 1/1] x86/bugs: Implement mitigation for Predictive Store Babu Moger
2021-09-01 20:30 ` Babu Moger
2021-09-01 20:35 ` Babu Moger
2021-09-02 17:35 ` Pawan Gupta
2021-08-12 23:44 ` [v6 1/1] x86/bugs: Implement mitigation for Predictive Store Forwarding Josh Poimboeuf
2021-09-02 18:16 ` [v6 1/1] x86/bugs: Implement mitigation for Predictive Store Babu Moger
2021-09-03 0:07 ` Josh Poimboeuf
[not found] ` <dca004cf-bacc-1a1f-56d6-c06e8bec167a@amd.com>
2021-09-04 17:23 ` Josh Poimboeuf
2021-09-07 23:15 ` Babu Moger
2021-09-08 18:20 ` Josh Poimboeuf [this message]
2021-09-10 16:08 ` Babu Moger
2021-09-09 16:20 ` Bandan Das
2021-06-17 20:47 ` [v6 0/1] Introduce support for PSF control Saripalli, RK
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=20210908182047.lcor52bjzrt35gsq@treble \
--to=jpoimboe@redhat.com \
--cc=babu.moger@amd.com \
--cc=bmoger@amd.com \
--cc=bp@alien8.de \
--cc=bsd@redhat.com \
--cc=corbet@lwn.net \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=tglx@linutronix.de \
--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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.