All of lore.kernel.org
 help / color / mirror / Atom feed
From: Peter Zijlstra <peterz@infradead.org>
To: speck@linutronix.de
Subject: [MODERATED] Re: L1D-Fault KVM mitigation
Date: Tue, 24 Apr 2018 13:04:45 +0200	[thread overview]
Message-ID: <20180424110445.GU4043@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <1524563292.8691.38.camel@infradead.org>

On Tue, Apr 24, 2018 at 10:48:12AM +0100, speck for David Woodhouse wrote:
> On Tue, 2018-04-24 at 11:35 +0200, speck for Peter Zijlstra wrote:
> > 
> > Another option, that is being explored, is to co-schedule siblings.
> > So ensure all siblings either run vcpus of the _same_ VM or idle.
> > 
> > Of course, this is all rather intrusive and ugly and brings with it
> > setup costs as well, because you'd have to sync up on VMENTER, VMEXIT
> > and interrupts (on the idle CPUs).
> 
> I hate to suggest more microcode hacks but... if there was an MSR bit
> which, when set, would pause any HT sibling that was currently in VMX
> non-root mode, then we could set that up to be automatically set on
> vmexit and it would automatically pause the problematic siblings.
> Meaning that co-ordinating vmexits with them might actually be
> feasible?

Not sure I'm following. The above assumes a sibling is running a VCPU of
another VM, right? But it could equally well run any regular old task
(including idle).

So only pausing siblings in VMX mode wouldn't help anything. The !VMX
tasks could still be loading stuff into L1.

  reply	other threads:[~2018-04-24 11:04 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-24  9:06 [MODERATED] L1D-Fault KVM mitigation Joerg Roedel
2018-04-24  9:35 ` [MODERATED] " Peter Zijlstra
2018-04-24  9:48   ` David Woodhouse
2018-04-24 11:04     ` Peter Zijlstra [this message]
2018-04-24 11:16       ` David Woodhouse
2018-04-24 15:10         ` Jon Masters
2018-05-23  9:45       ` David Woodhouse
2018-05-24  9:45         ` Peter Zijlstra
2018-05-24 14:14           ` Jon Masters
2018-05-24 15:04           ` Thomas Gleixner
2018-05-24 15:33             ` Thomas Gleixner
2018-05-24 15:38               ` [MODERATED] " Jiri Kosina
2018-05-24 17:22                 ` Dave Hansen
2018-05-24 17:30                   ` Linus Torvalds
2018-05-24 23:18               ` [MODERATED] Encrypted Message Tim Chen
2018-05-24 23:28                 ` [MODERATED] Re: L1D-Fault KVM mitigation Linus Torvalds
2018-05-25  8:31                   ` Thomas Gleixner
2018-05-28 14:43                     ` [MODERATED] " Paolo Bonzini
2018-05-25 18:22                 ` [MODERATED] Encrypted Message Tim Chen
2018-05-26 19:14                 ` L1D-Fault KVM mitigation Thomas Gleixner
2018-05-26 20:43                   ` [MODERATED] " Andi Kleen
2018-05-26 20:48                     ` Linus Torvalds
2018-05-27 18:25                       ` Andi Kleen
2018-05-27 18:49                         ` Linus Torvalds
2018-05-27 18:57                           ` Thomas Gleixner
2018-05-27 19:13                           ` [MODERATED] " Andrew Cooper
2018-05-27 19:26                             ` Linus Torvalds
2018-05-27 19:41                               ` Thomas Gleixner
2018-05-27 22:26                                 ` [MODERATED] " Andrew Cooper
2018-05-28  6:47                                   ` Thomas Gleixner
2018-05-28 12:26                                     ` [MODERATED] " Andrew Cooper
2018-05-28 14:40                           ` Paolo Bonzini
2018-05-28 15:56                             ` Thomas Gleixner
2018-05-28 17:15                               ` [MODERATED] " Paolo Bonzini
2018-05-27 15:42                     ` Thomas Gleixner
2018-05-27 16:26                       ` [MODERATED] " Linus Torvalds
2018-05-27 18:31                       ` Andi Kleen
2018-05-29 19:29                   ` [MODERATED] Encrypted Message Tim Chen
2018-05-29 21:14                     ` L1D-Fault KVM mitigation Thomas Gleixner
2018-05-30 16:38                       ` [MODERATED] Encrypted Message Tim Chen
2018-05-24 15:44             ` [MODERATED] Re: L1D-Fault KVM mitigation Andi Kleen
2018-05-24 15:38           ` Linus Torvalds
2018-05-24 15:59             ` David Woodhouse
2018-05-24 16:35               ` Linus Torvalds
2018-05-24 16:51                 ` David Woodhouse
2018-05-24 16:57                   ` Linus Torvalds
2018-05-25 11:29                     ` David Woodhouse
2018-04-24 10:30   ` [MODERATED] Re: ***UNCHECKED*** " Joerg Roedel
2018-04-24 11:09     ` Thomas Gleixner
2018-04-24 16:06       ` [MODERATED] " Andi Kleen
2018-04-24 12:53   ` Paolo Bonzini
2018-05-03 16:20     ` Konrad Rzeszutek Wilk
2018-05-07 17:11       ` Paolo Bonzini
2018-05-16  8:51         ` Jiri Kosina
2018-05-16  8:53           ` Paolo Bonzini
2018-05-21 10:06             ` David Woodhouse
2018-05-21 13:40               ` Thomas Gleixner

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=20180424110445.GU4043@hirez.programming.kicks-ass.net \
    --to=peterz@infradead.org \
    --cc=speck@linutronix.de \
    /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.