From: Andi Kleen <ak@linux.intel.com>
To: "Maciej S. Szmigiero" <mail@maciej.szmigiero.name>
Cc: "Woodhouse, David" <dwmw@amazon.co.uk>,
Paul Turner <pjt@google.com>, LKML <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@linux-foundation.org>,
Tim Chen <tim.c.chen@linux.intel.com>,
Dave Hansen <dave.hansen@intel.com>,
tglx@linutronix.de, Kees Cook <keescook@google.com>,
Rik van Riel <riel@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Andy Lutomirski <luto@amacapital.net>,
Jiri Kosina <jikos@kernel.org>,
gnomes@lxorguk.ukuu.org.uk, x86@kernel.org,
thomas.lendacky@amd.com, Josh Poimboeuf <jpoimboe@redhat.com>
Subject: Re: x86/retpoline: Fill RSB on context switch for affected CPUs
Date: Fri, 9 Mar 2018 07:14:28 -0800 [thread overview]
Message-ID: <20180309151428.GE22087@tassilo.jf.intel.com> (raw)
In-Reply-To: <f2faf9ff-8955-d8b5-c521-91b9c273128b@maciej.szmigiero.name>
> Shouldn't the RSB filling on context switch also be done on non-IBPB
> CPUs to protect (retpolined) user space tasks from other user space
> tasks?
The comment is actually incorrect. There's no risk to hit user space
addresses if we have KPTI and NX (which is fairly universal).
It's mainly needed on Skylake era CPUs.
Should fix the comment. I'll send a patch.
-Andi
next prev parent reply other threads:[~2018-03-09 15:14 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-12 17:49 [PATCH] x86/retpoline: Fill RSB on context switch for affected CPUs David Woodhouse
2018-01-12 18:02 ` Andi Kleen
2018-01-12 18:23 ` David Woodhouse
2018-01-12 18:05 ` Andrew Cooper
2018-01-12 18:56 ` David Woodhouse
2018-01-12 23:41 ` Josh Poimboeuf
2018-01-14 11:39 ` Thomas Gleixner
2018-01-14 17:04 ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-15 14:35 ` David Laight
2018-01-15 14:39 ` David Woodhouse
2018-01-15 14:42 ` Arjan van de Ven
2018-01-15 20:03 ` Kees Cook
2018-01-14 23:37 ` tip-bot for David Woodhouse
2018-01-15 0:05 ` Andi Kleen
2018-01-15 0:09 ` Andi Kleen
2018-01-15 10:13 ` David Woodhouse
2018-03-09 13:12 ` Maciej S. Szmigiero
2018-03-09 15:14 ` Andi Kleen [this message]
2018-03-09 15:33 ` Maciej S. Szmigiero
2018-03-09 15:38 ` Woodhouse, David
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