linux-kernel - Re: [PATCH 3/3] KVM: VMX: Extend VMX's #AC interceptor to handle split lock #AC in guest

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20200402204816.GJ2452@worktop.programming.kicks-ass.net>
Date:   Thu, 2 Apr 2020 22:48:16 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        x86@...nel.org, "Kenneth R . Crudup" <kenny@...ix.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Xiaoyao Li <xiaoyao.li@...el.com>,
        Nadav Amit <namit@...are.com>,
        Thomas Hellstrom <thellstrom@...are.com>,
        Tony Luck <tony.luck@...el.com>, Jessica Yu <jeyu@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] KVM: VMX: Extend VMX's #AC interceptor to handle
 split lock #AC in guest

On Thu, Apr 02, 2020 at 10:07:07PM +0200, Thomas Gleixner wrote:

If we're doing wish lists, I have one more ;-)

> TBH, the more I learn about this, the more I tend to just give up on
> this whole split lock stuff in its current form and wait until HW folks
> provide something which is actually usable:
> 
>    - Per thread
>    - Properly distinguishable from a regular #AC via error code

   - is an actual alignment check.

That is, disallow all unaligned LOCK prefixed ops, not just those that
happen to straddle a cacheline.