linux-kernel - Re: [PATCH RFC] KVM: nSVM: Fix L1 state corruption upon return from SMM

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: <a3918bfa-7b4f-c31a-448a-aa22a44d4dfd@redhat.com>
Date:   Wed, 23 Jun 2021 11:39:31 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>, kvm@...r.kernel.org
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        Cathy Avery <cavery@...hat.com>,
        Emanuele Giuseppe Esposito <eesposit@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] KVM: nSVM: Fix L1 state corruption upon return from
 SMM

On 23/06/21 09:44, Vitaly Kuznetsov wrote:
> - RFC: I'm not 100% sure my 'smart' idea to use currently-unused HSAVE area
> is that smart. Also, we don't even seem to check that L1 set it up upon
> nested VMRUN so hypervisors which don't do that may remain broken. A very
> much needed selftest is also missing.

It's certainly a bit weird, but I guess it counts as smart too.  It 
needs a few more comments, but I think it's a good solution.

One could delay the backwards memcpy until vmexit time, but that would 
require a new flag so it's not worth it for what is a pretty rare and 
already expensive case.

Paolo