linux-kernel - Re: [PATCH 00/14] KVM: x86/mmu: Dirty logging fixes and improvements

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: <YC2d0ZkdCOJEWlng@google.com>
Date:   Wed, 17 Feb 2021 14:50:57 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Ben Gardon <bgardon@...gle.com>,
        Makarand Sonare <makarandsonare@...gle.com>
Subject: Re: [PATCH 00/14] KVM: x86/mmu: Dirty logging fixes and improvements

On Fri, Feb 12, 2021, Sean Christopherson wrote:
> Paolo, this is more or less ready, but on final read-through before
> sending I realized it would be a good idea to WARN during VM destruction
> if cpu_dirty_logging_count is non-zero.  I wanted to get you this before
> the 5.12 window opens in case you want the TDP MMU fixes for 5.12.  I'll
> do the above change and retest next week (note, Monday is a US holiday).

Verified cpu_dirty_logging_count does indeed hit zero during VM destruction.

Adding a WARN to KVM would require adding an arch hook to kvm_free_memslots(),
otherwise the count will be non-zero if the VM is destroyed with dirty logging
active.  That doesn't seem worthwhile, so I'm not planning on pursuing a WARN
for the upstream code.