linux-kernel - Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor

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: <jpginixjzvr.fsf@linux.bootlegged.copy>
Date:   Wed, 12 Jul 2017 14:04:08 -0400
From:   Bandan Das <bsd@...hat.com>
To:     Radim Krčmář <rkrcmar@...hat.com>
Cc:     Jim Mattson <jmattson@...gle.com>,
        David Hildenbrand <david@...hat.com>,
        kvm list <kvm@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor

Radim Krčmář <rkrcmar@...hat.com> writes:
...
>> > Thanks, we're not here to judge the guest, but to provide a bare-metal
>> > experience. :)
>> 
>> There are certain cases where do. For example, when L2 instruction emulation
>> fails we decide to kill L2 instead of injecting the error to L1 and let it handle
>> that. Anyway, that's a different topic, I was just trying to point out there
>> are cases kvm does a somewhat policy decision...
>
> Emulation failure is a KVM bug and we are too lazy to implement the
> bare-metal behavior correctly, but avoiding the EPTP list bug is
> actually easier than introducing it.  You can make KVM simpler and
> improve bare-metal emulation at the same time.

We are just talking past each other here trying to impose point of views.
Checking for 0 makes KVM simpler. As I said before, a 0 list_address means
that the hypervisor forgot to initialize it. Feel free to show me examples
where the hypervisor does indeed use a 0 address for eptp list address or
anything vm specific. You disagreed and I am fine with it.