From: Peter Zijlstra <peterz@infradead.org>
To: speck@linutronix.de
Subject: [MODERATED] Re: [patch V2 09/10] MDS basics+ 9
Date: Wed, 20 Feb 2019 17:21:28 +0100 [thread overview]
Message-ID: <20190220162128.GW32477@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190220151400.787843957@linutronix.de>
On Wed, Feb 20, 2019 at 04:08:02PM +0100, speck for Thomas Gleixner wrote:
> static inline void mds_user_clear_cpu_buffers(void)
> {
> + if (static_branch_likely(&mds_user_clear_cond)) {
Are we sure we want _likely() ? That puts the body in-line.
> + if (__this_cpu_read(mds_cond_clear)) {
> + __this_cpu_write(mds_cond_clear, 0);
> + mds_clear_cpu_buffers();
> + }
return;
_might_ generate better code; by making it explitit we'll never have
both branches enabled at the same time.
> + }
> if (static_branch_likely(&mds_user_clear_always))
> mds_clear_cpu_buffers();
> }
And in general; yuck! Should I once again look at tri-state jump_labels
or static_switch? Last time I tried I got stuck on the C part, writing
different targets is trivial.
Ideally we'd end up with something like:
1: jmp 3f
test $1, %gs:mds_cond_clear
jz 3f
mov $0, %gs:mds_cond_clear
2: verw ds
3:
And change the jmp at 1 between: JMP 3f, JMP 2f and NOP for
mds={off,full,cond} resp.
next prev parent reply other threads:[~2019-02-20 16:21 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-20 15:07 [patch V2 00/10] MDS basics+ 0 Thomas Gleixner
2019-02-20 15:07 ` [patch V2 01/10] MDS basics+ 1 Thomas Gleixner
2019-02-20 16:27 ` [MODERATED] " Borislav Petkov
2019-02-20 16:46 ` Greg KH
2019-02-20 15:07 ` [patch V2 02/10] MDS basics+ 2 Thomas Gleixner
2019-02-20 16:47 ` [MODERATED] " Borislav Petkov
2019-02-20 16:48 ` Greg KH
2019-02-20 15:07 ` [patch V2 03/10] MDS basics+ 3 Thomas Gleixner
2019-02-20 16:54 ` [MODERATED] " mark gross
2019-02-20 16:57 ` Thomas Gleixner
2019-02-20 18:08 ` [MODERATED] " mark gross
2019-02-20 21:40 ` Thomas Gleixner
2019-02-20 17:14 ` [MODERATED] " Borislav Petkov
2019-02-20 21:31 ` Thomas Gleixner
2019-02-21 2:12 ` [MODERATED] " Andrew Cooper
2019-02-21 9:27 ` Peter Zijlstra
2019-02-21 9:33 ` [MODERATED] " Borislav Petkov
2019-02-21 10:04 ` Thomas Gleixner
2019-02-21 10:18 ` [MODERATED] Re: " Borislav Petkov
2019-02-20 15:07 ` [patch V2 04/10] MDS basics+ 4 Thomas Gleixner
2019-02-20 16:52 ` [MODERATED] " Greg KH
2019-02-20 17:10 ` mark gross
2019-02-21 19:26 ` [MODERATED] Encrypted Message Tim Chen
2019-02-21 20:32 ` Thomas Gleixner
2019-02-21 21:07 ` [MODERATED] " Jiri Kosina
2019-02-20 18:43 ` [MODERATED] Re: [patch V2 04/10] MDS basics+ 4 Borislav Petkov
2019-02-20 19:26 ` Jiri Kosina
2019-02-20 21:42 ` Thomas Gleixner
2019-02-20 15:07 ` [patch V2 05/10] MDS basics+ 5 Thomas Gleixner
2019-02-20 20:05 ` [MODERATED] " Borislav Petkov
2019-02-21 2:24 ` Andrew Cooper
2019-02-21 10:36 ` Thomas Gleixner
2019-02-21 11:22 ` Thomas Gleixner
2019-02-21 11:51 ` [MODERATED] Attack Surface [Was [patch V2 05/10] MDS basics+ 5] Andrew Cooper
2019-02-21 18:41 ` Thomas Gleixner
2019-02-20 15:07 ` [patch V2 06/10] MDS basics+ 6 Thomas Gleixner
2019-02-21 10:18 ` [MODERATED] " Borislav Petkov
2019-02-20 15:08 ` [patch V2 07/10] MDS basics+ 7 Thomas Gleixner
2019-02-21 12:47 ` [MODERATED] " Borislav Petkov
2019-02-21 13:48 ` Thomas Gleixner
2019-02-20 15:08 ` [patch V2 08/10] MDS basics+ 8 Thomas Gleixner
2019-02-21 14:04 ` [MODERATED] " Borislav Petkov
2019-02-21 14:11 ` Thomas Gleixner
2019-02-20 15:08 ` [patch V2 09/10] MDS basics+ 9 Thomas Gleixner
2019-02-20 16:21 ` Peter Zijlstra [this message]
2019-02-20 22:32 ` Thomas Gleixner
2019-02-20 22:50 ` [MODERATED] " Jiri Kosina
2019-02-20 23:22 ` Thomas Gleixner
2019-02-21 11:04 ` [MODERATED] " Peter Zijlstra
2019-02-21 11:50 ` Peter Zijlstra
2019-02-21 14:18 ` Borislav Petkov
2019-02-21 18:00 ` Kees Cook
2019-02-21 19:46 ` Thomas Gleixner
2019-02-21 20:56 ` Thomas Gleixner
2019-02-20 15:08 ` [patch V2 10/10] MDS basics+ 10 Thomas Gleixner
2019-02-22 16:05 ` [MODERATED] Re: [patch V2 00/10] MDS basics+ 0 mark gross
2019-02-22 17:12 ` Thomas Gleixner
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